idmvton

BasicSR/basicsr/archs/__init__.py

+import importlib
+from copy import deepcopy
+from os import path as osp
+
+from basicsr.utils import get_root_logger, scandir
+from basicsr.utils.registry import ARCH_REGISTRY
+
+__all__ = ['build_network']
+
+# automatically scan and import arch modules for registry
+# scan all the files under the 'archs' folder and collect files ending with '_arch.py'
+arch_folder = osp.dirname(osp.abspath(__file__))
+arch_filenames = [osp.splitext(osp.basename(v))[0] for v in scandir(arch_folder) if v.endswith('_arch.py')]
+# import all the arch modules
+_arch_modules = [importlib.import_module(f'basicsr.archs.{file_name}') for file_name in arch_filenames]
+
+
+def build_network(opt):
+    opt = deepcopy(opt)
+    network_type = opt.pop('type')
+    net = ARCH_REGISTRY.get(network_type)(**opt)
+    logger = get_root_logger()
+    logger.info(f'Network [{net.__class__.__name__}] is created.')
+    return net

BasicSR/basicsr/archs/arch_util.py

+import collections.abc
+import math
+import torch
+import torchvision
+import warnings
+from distutils.version import LooseVersion
+from itertools import repeat
+from torch import nn as nn
+from torch.nn import functional as F
+from torch.nn import init as init
+from torch.nn.modules.batchnorm import _BatchNorm
+
+from basicsr.ops.dcn import ModulatedDeformConvPack, modulated_deform_conv
+from basicsr.utils import get_root_logger
+
+
+@torch.no_grad()
+def default_init_weights(module_list, scale=1, bias_fill=0, **kwargs):
+    """Initialize network weights.
+
+    Args:
+        module_list (list[nn.Module] | nn.Module): Modules to be initialized.
+        scale (float): Scale initialized weights, especially for residual
+            blocks. Default: 1.
+        bias_fill (float): The value to fill bias. Default: 0
+        kwargs (dict): Other arguments for initialization function.
+    """
+    if not isinstance(module_list, list):
+        module_list = [module_list]
+    for module in module_list:
+        for m in module.modules():
+            if isinstance(m, nn.Conv2d):
+                init.kaiming_normal_(m.weight, **kwargs)
+                m.weight.data *= scale
+                if m.bias is not None:
+                    m.bias.data.fill_(bias_fill)
+            elif isinstance(m, nn.Linear):
+                init.kaiming_normal_(m.weight, **kwargs)
+                m.weight.data *= scale
+                if m.bias is not None:
+                    m.bias.data.fill_(bias_fill)
+            elif isinstance(m, _BatchNorm):
+                init.constant_(m.weight, 1)
+                if m.bias is not None:
+                    m.bias.data.fill_(bias_fill)
+
+
+def make_layer(basic_block, num_basic_block, **kwarg):
+    """Make layers by stacking the same blocks.
+
+    Args:
+        basic_block (nn.module): nn.module class for basic block.
+        num_basic_block (int): number of blocks.
+
+    Returns:
+        nn.Sequential: Stacked blocks in nn.Sequential.
+    """
+    layers = []
+    for _ in range(num_basic_block):
+        layers.append(basic_block(**kwarg))
+    return nn.Sequential(*layers)
+
+
+class ResidualBlockNoBN(nn.Module):
+    """Residual block without BN.
+
+    Args:
+        num_feat (int): Channel number of intermediate features.
+            Default: 64.
+        res_scale (float): Residual scale. Default: 1.
+        pytorch_init (bool): If set to True, use pytorch default init,
+            otherwise, use default_init_weights. Default: False.
+    """
+
+    def __init__(self, num_feat=64, res_scale=1, pytorch_init=False):
+        super(ResidualBlockNoBN, self).__init__()
+        self.res_scale = res_scale
+        self.conv1 = nn.Conv2d(num_feat, num_feat, 3, 1, 1, bias=True)
+        self.conv2 = nn.Conv2d(num_feat, num_feat, 3, 1, 1, bias=True)
+        self.relu = nn.ReLU(inplace=True)
+
+        if not pytorch_init:
+            default_init_weights([self.conv1, self.conv2], 0.1)
+
+    def forward(self, x):
+        identity = x
+        out = self.conv2(self.relu(self.conv1(x)))
+        return identity + out * self.res_scale
+
+
+class Upsample(nn.Sequential):
+    """Upsample module.
+
+    Args:
+        scale (int): Scale factor. Supported scales: 2^n and 3.
+        num_feat (int): Channel number of intermediate features.
+    """
+
+    def __init__(self, scale, num_feat):
+        m = []
+        if (scale & (scale - 1)) == 0:  # scale = 2^n
+            for _ in range(int(math.log(scale, 2))):
+                m.append(nn.Conv2d(num_feat, 4 * num_feat, 3, 1, 1))
+                m.append(nn.PixelShuffle(2))
+        elif scale == 3:
+            m.append(nn.Conv2d(num_feat, 9 * num_feat, 3, 1, 1))
+            m.append(nn.PixelShuffle(3))
+        else:
+            raise ValueError(f'scale {scale} is not supported. Supported scales: 2^n and 3.')
+        super(Upsample, self).__init__(*m)
+
+
+def flow_warp(x, flow, interp_mode='bilinear', padding_mode='zeros', align_corners=True):
+    """Warp an image or feature map with optical flow.
+
+    Args:
+        x (Tensor): Tensor with size (n, c, h, w).
+        flow (Tensor): Tensor with size (n, h, w, 2), normal value.
+        interp_mode (str): 'nearest' or 'bilinear'. Default: 'bilinear'.
+        padding_mode (str): 'zeros' or 'border' or 'reflection'.
+            Default: 'zeros'.
+        align_corners (bool): Before pytorch 1.3, the default value is
+            align_corners=True. After pytorch 1.3, the default value is
+            align_corners=False. Here, we use the True as default.
+
+    Returns:
+        Tensor: Warped image or feature map.
+    """
+    assert x.size()[-2:] == flow.size()[1:3]
+    _, _, h, w = x.size()
+    # create mesh grid
+    grid_y, grid_x = torch.meshgrid(torch.arange(0, h).type_as(x), torch.arange(0, w).type_as(x))
+    grid = torch.stack((grid_x, grid_y), 2).float()  # W(x), H(y), 2
+    grid.requires_grad = False
+
+    vgrid = grid + flow
+    # scale grid to [-1,1]
+    vgrid_x = 2.0 * vgrid[:, :, :, 0] / max(w - 1, 1) - 1.0
+    vgrid_y = 2.0 * vgrid[:, :, :, 1] / max(h - 1, 1) - 1.0
+    vgrid_scaled = torch.stack((vgrid_x, vgrid_y), dim=3)
+    output = F.grid_sample(x, vgrid_scaled, mode=interp_mode, padding_mode=padding_mode, align_corners=align_corners)
+
+    # TODO, what if align_corners=False
+    return output
+
+
+def resize_flow(flow, size_type, sizes, interp_mode='bilinear', align_corners=False):
+    """Resize a flow according to ratio or shape.
+
+    Args:
+        flow (Tensor): Precomputed flow. shape [N, 2, H, W].
+        size_type (str): 'ratio' or 'shape'.
+        sizes (list[int | float]): the ratio for resizing or the final output
+            shape.
+            1) The order of ratio should be [ratio_h, ratio_w]. For
+            downsampling, the ratio should be smaller than 1.0 (i.e., ratio
+            < 1.0). For upsampling, the ratio should be larger than 1.0 (i.e.,
+            ratio > 1.0).
+            2) The order of output_size should be [out_h, out_w].
+        interp_mode (str): The mode of interpolation for resizing.
+            Default: 'bilinear'.
+        align_corners (bool): Whether align corners. Default: False.
+
+    Returns:
+        Tensor: Resized flow.
+    """
+    _, _, flow_h, flow_w = flow.size()
+    if size_type == 'ratio':
+        output_h, output_w = int(flow_h * sizes[0]), int(flow_w * sizes[1])
+    elif size_type == 'shape':
+        output_h, output_w = sizes[0], sizes[1]
+    else:
+        raise ValueError(f'Size type should be ratio or shape, but got type {size_type}.')
+
+    input_flow = flow.clone()
+    ratio_h = output_h / flow_h
+    ratio_w = output_w / flow_w
+    input_flow[:, 0, :, :] *= ratio_w
+    input_flow[:, 1, :, :] *= ratio_h
+    resized_flow = F.interpolate(
+        input=input_flow, size=(output_h, output_w), mode=interp_mode, align_corners=align_corners)
+    return resized_flow
+
+
+# TODO: may write a cpp file
+def pixel_unshuffle(x, scale):
+    """ Pixel unshuffle.
+
+    Args:
+        x (Tensor): Input feature with shape (b, c, hh, hw).
+        scale (int): Downsample ratio.
+
+    Returns:
+        Tensor: the pixel unshuffled feature.
+    """
+    b, c, hh, hw = x.size()
+    out_channel = c * (scale**2)
+    assert hh % scale == 0 and hw % scale == 0
+    h = hh // scale
+    w = hw // scale
+    x_view = x.view(b, c, h, scale, w, scale)
+    return x_view.permute(0, 1, 3, 5, 2, 4).reshape(b, out_channel, h, w)
+
+
+class DCNv2Pack(ModulatedDeformConvPack):
+    """Modulated deformable conv for deformable alignment.
+
+    Different from the official DCNv2Pack, which generates offsets and masks
+    from the preceding features, this DCNv2Pack takes another different
+    features to generate offsets and masks.
+
+    ``Paper: Delving Deep into Deformable Alignment in Video Super-Resolution``
+    """
+
+    def forward(self, x, feat):
+        out = self.conv_offset(feat)
+        o1, o2, mask = torch.chunk(out, 3, dim=1)
+        offset = torch.cat((o1, o2), dim=1)
+        mask = torch.sigmoid(mask)
+
+        offset_absmean = torch.mean(torch.abs(offset))
+        if offset_absmean > 50:
+            logger = get_root_logger()
+            logger.warning(f'Offset abs mean is {offset_absmean}, larger than 50.')
+
+        if LooseVersion(torchvision.__version__) >= LooseVersion('0.9.0'):
+            return torchvision.ops.deform_conv2d(x, offset, self.weight, self.bias, self.stride, self.padding,
+                                                 self.dilation, mask)
+        else:
+            return modulated_deform_conv(x, offset, mask, self.weight, self.bias, self.stride, self.padding,
+                                         self.dilation, self.groups, self.deformable_groups)
+
+
+def _no_grad_trunc_normal_(tensor, mean, std, a, b):
+    # From: https://github.com/rwightman/pytorch-image-models/blob/master/timm/models/layers/weight_init.py
+    # Cut & paste from PyTorch official master until it's in a few official releases - RW
+    # Method based on https://people.sc.fsu.edu/~jburkardt/presentations/truncated_normal.pdf
+    def norm_cdf(x):
+        # Computes standard normal cumulative distribution function
+        return (1. + math.erf(x / math.sqrt(2.))) / 2.
+
+    if (mean < a - 2 * std) or (mean > b + 2 * std):
+        warnings.warn(
+            'mean is more than 2 std from [a, b] in nn.init.trunc_normal_. '
+            'The distribution of values may be incorrect.',
+            stacklevel=2)
+
+    with torch.no_grad():
+        # Values are generated by using a truncated uniform distribution and
+        # then using the inverse CDF for the normal distribution.
+        # Get upper and lower cdf values
+        low = norm_cdf((a - mean) / std)
+        up = norm_cdf((b - mean) / std)
+
+        # Uniformly fill tensor with values from [low, up], then translate to
+        # [2l-1, 2u-1].
+        tensor.uniform_(2 * low - 1, 2 * up - 1)
+
+        # Use inverse cdf transform for normal distribution to get truncated
+        # standard normal
+        tensor.erfinv_()
+
+        # Transform to proper mean, std
+        tensor.mul_(std * math.sqrt(2.))
+        tensor.add_(mean)
+
+        # Clamp to ensure it's in the proper range
+        tensor.clamp_(min=a, max=b)
+        return tensor
+
+
+def trunc_normal_(tensor, mean=0., std=1., a=-2., b=2.):
+    r"""Fills the input Tensor with values drawn from a truncated
+    normal distribution.
+
+    From: https://github.com/rwightman/pytorch-image-models/blob/master/timm/models/layers/weight_init.py
+
+    The values are effectively drawn from the
+    normal distribution :math:`\mathcal{N}(\text{mean}, \text{std}^2)`
+    with values outside :math:`[a, b]` redrawn until they are within
+    the bounds. The method used for generating the random values works
+    best when :math:`a \leq \text{mean} \leq b`.
+
+    Args:
+        tensor: an n-dimensional `torch.Tensor`
+        mean: the mean of the normal distribution
+        std: the standard deviation of the normal distribution
+        a: the minimum cutoff value
+        b: the maximum cutoff value
+
+    Examples:
+        >>> w = torch.empty(3, 5)
+        >>> nn.init.trunc_normal_(w)
+    """
+    return _no_grad_trunc_normal_(tensor, mean, std, a, b)
+
+
+# From PyTorch
+def _ntuple(n):
+
+    def parse(x):
+        if isinstance(x, collections.abc.Iterable):
+            return x
+        return tuple(repeat(x, n))
+
+    return parse
+
+
+to_1tuple = _ntuple(1)
+to_2tuple = _ntuple(2)
+to_3tuple = _ntuple(3)
+to_4tuple = _ntuple(4)
+to_ntuple = _ntuple

BasicSR/basicsr/archs/basicvsr_arch.py

+import torch
+from torch import nn as nn
+from torch.nn import functional as F
+
+from basicsr.utils.registry import ARCH_REGISTRY
+from .arch_util import ResidualBlockNoBN, flow_warp, make_layer
+from .edvr_arch import PCDAlignment, TSAFusion
+from .spynet_arch import SpyNet
+
+
+@ARCH_REGISTRY.register()
+class BasicVSR(nn.Module):
+    """A recurrent network for video SR. Now only x4 is supported.
+
+    Args:
+        num_feat (int): Number of channels. Default: 64.
+        num_block (int): Number of residual blocks for each branch. Default: 15
+        spynet_path (str): Path to the pretrained weights of SPyNet. Default: None.
+    """
+
+    def __init__(self, num_feat=64, num_block=15, spynet_path=None):
+        super().__init__()
+        self.num_feat = num_feat
+
+        # alignment
+        self.spynet = SpyNet(spynet_path)
+
+        # propagation
+        self.backward_trunk = ConvResidualBlocks(num_feat + 3, num_feat, num_block)
+        self.forward_trunk = ConvResidualBlocks(num_feat + 3, num_feat, num_block)
+
+        # reconstruction
+        self.fusion = nn.Conv2d(num_feat * 2, num_feat, 1, 1, 0, bias=True)
+        self.upconv1 = nn.Conv2d(num_feat, num_feat * 4, 3, 1, 1, bias=True)
+        self.upconv2 = nn.Conv2d(num_feat, 64 * 4, 3, 1, 1, bias=True)
+        self.conv_hr = nn.Conv2d(64, 64, 3, 1, 1)
+        self.conv_last = nn.Conv2d(64, 3, 3, 1, 1)
+
+        self.pixel_shuffle = nn.PixelShuffle(2)
+
+        # activation functions
+        self.lrelu = nn.LeakyReLU(negative_slope=0.1, inplace=True)
+
+    def get_flow(self, x):
+        b, n, c, h, w = x.size()
+
+        x_1 = x[:, :-1, :, :, :].reshape(-1, c, h, w)
+        x_2 = x[:, 1:, :, :, :].reshape(-1, c, h, w)
+
+        flows_backward = self.spynet(x_1, x_2).view(b, n - 1, 2, h, w)
+        flows_forward = self.spynet(x_2, x_1).view(b, n - 1, 2, h, w)
+
+        return flows_forward, flows_backward
+
+    def forward(self, x):
+        """Forward function of BasicVSR.
+
+        Args:
+            x: Input frames with shape (b, n, c, h, w). n is the temporal dimension / number of frames.
+        """
+        flows_forward, flows_backward = self.get_flow(x)
+        b, n, _, h, w = x.size()
+
+        # backward branch
+        out_l = []
+        feat_prop = x.new_zeros(b, self.num_feat, h, w)
+        for i in range(n - 1, -1, -1):
+            x_i = x[:, i, :, :, :]
+            if i < n - 1:
+                flow = flows_backward[:, i, :, :, :]
+                feat_prop = flow_warp(feat_prop, flow.permute(0, 2, 3, 1))
+            feat_prop = torch.cat([x_i, feat_prop], dim=1)
+            feat_prop = self.backward_trunk(feat_prop)
+            out_l.insert(0, feat_prop)
+
+        # forward branch
+        feat_prop = torch.zeros_like(feat_prop)
+        for i in range(0, n):
+            x_i = x[:, i, :, :, :]
+            if i > 0:
+                flow = flows_forward[:, i - 1, :, :, :]
+                feat_prop = flow_warp(feat_prop, flow.permute(0, 2, 3, 1))
+
+            feat_prop = torch.cat([x_i, feat_prop], dim=1)
+            feat_prop = self.forward_trunk(feat_prop)
+
+            # upsample
+            out = torch.cat([out_l[i], feat_prop], dim=1)
+            out = self.lrelu(self.fusion(out))
+            out = self.lrelu(self.pixel_shuffle(self.upconv1(out)))
+            out = self.lrelu(self.pixel_shuffle(self.upconv2(out)))
+            out = self.lrelu(self.conv_hr(out))
+            out = self.conv_last(out)
+            base = F.interpolate(x_i, scale_factor=4, mode='bilinear', align_corners=False)
+            out += base
+            out_l[i] = out
+
+        return torch.stack(out_l, dim=1)
+
+
+class ConvResidualBlocks(nn.Module):
+    """Conv and residual block used in BasicVSR.
+
+    Args:
+        num_in_ch (int): Number of input channels. Default: 3.
+        num_out_ch (int): Number of output channels. Default: 64.
+        num_block (int): Number of residual blocks. Default: 15.
+    """
+
+    def __init__(self, num_in_ch=3, num_out_ch=64, num_block=15):
+        super().__init__()
+        self.main = nn.Sequential(
+            nn.Conv2d(num_in_ch, num_out_ch, 3, 1, 1, bias=True), nn.LeakyReLU(negative_slope=0.1, inplace=True),
+            make_layer(ResidualBlockNoBN, num_block, num_feat=num_out_ch))
+
+    def forward(self, fea):
+        return self.main(fea)
+
+
+@ARCH_REGISTRY.register()
+class IconVSR(nn.Module):
+    """IconVSR, proposed also in the BasicVSR paper.
+
+    Args:
+        num_feat (int): Number of channels. Default: 64.
+        num_block (int): Number of residual blocks for each branch. Default: 15.
+        keyframe_stride (int): Keyframe stride. Default: 5.
+        temporal_padding (int): Temporal padding. Default: 2.
+        spynet_path (str): Path to the pretrained weights of SPyNet. Default: None.
+        edvr_path (str): Path to the pretrained EDVR model. Default: None.
+    """
+
+    def __init__(self,
+                 num_feat=64,
+                 num_block=15,
+                 keyframe_stride=5,
+                 temporal_padding=2,
+                 spynet_path=None,
+                 edvr_path=None):
+        super().__init__()
+
+        self.num_feat = num_feat
+        self.temporal_padding = temporal_padding
+        self.keyframe_stride = keyframe_stride
+
+        # keyframe_branch
+        self.edvr = EDVRFeatureExtractor(temporal_padding * 2 + 1, num_feat, edvr_path)
+        # alignment
+        self.spynet = SpyNet(spynet_path)
+
+        # propagation
+        self.backward_fusion = nn.Conv2d(2 * num_feat, num_feat, 3, 1, 1, bias=True)
+        self.backward_trunk = ConvResidualBlocks(num_feat + 3, num_feat, num_block)
+
+        self.forward_fusion = nn.Conv2d(2 * num_feat, num_feat, 3, 1, 1, bias=True)
+        self.forward_trunk = ConvResidualBlocks(2 * num_feat + 3, num_feat, num_block)
+
+        # reconstruction
+        self.upconv1 = nn.Conv2d(num_feat, num_feat * 4, 3, 1, 1, bias=True)
+        self.upconv2 = nn.Conv2d(num_feat, 64 * 4, 3, 1, 1, bias=True)
+        self.conv_hr = nn.Conv2d(64, 64, 3, 1, 1)
+        self.conv_last = nn.Conv2d(64, 3, 3, 1, 1)
+
+        self.pixel_shuffle = nn.PixelShuffle(2)
+
+        # activation functions
+        self.lrelu = nn.LeakyReLU(negative_slope=0.1, inplace=True)
+
+    def pad_spatial(self, x):
+        """Apply padding spatially.
+
+        Since the PCD module in EDVR requires that the resolution is a multiple
+        of 4, we apply padding to the input LR images if their resolution is
+        not divisible by 4.
+
+        Args:
+            x (Tensor): Input LR sequence with shape (n, t, c, h, w).
+        Returns:
+            Tensor: Padded LR sequence with shape (n, t, c, h_pad, w_pad).
+        """
+        n, t, c, h, w = x.size()
+
+        pad_h = (4 - h % 4) % 4
+        pad_w = (4 - w % 4) % 4
+
+        # padding
+        x = x.view(-1, c, h, w)
+        x = F.pad(x, [0, pad_w, 0, pad_h], mode='reflect')
+
+        return x.view(n, t, c, h + pad_h, w + pad_w)
+
+    def get_flow(self, x):
+        b, n, c, h, w = x.size()
+
+        x_1 = x[:, :-1, :, :, :].reshape(-1, c, h, w)
+        x_2 = x[:, 1:, :, :, :].reshape(-1, c, h, w)
+
+        flows_backward = self.spynet(x_1, x_2).view(b, n - 1, 2, h, w)
+        flows_forward = self.spynet(x_2, x_1).view(b, n - 1, 2, h, w)
+
+        return flows_forward, flows_backward
+
+    def get_keyframe_feature(self, x, keyframe_idx):
+        if self.temporal_padding == 2:
+            x = [x[:, [4, 3]], x, x[:, [-4, -5]]]
+        elif self.temporal_padding == 3:
+            x = [x[:, [6, 5, 4]], x, x[:, [-5, -6, -7]]]
+        x = torch.cat(x, dim=1)
+
+        num_frames = 2 * self.temporal_padding + 1
+        feats_keyframe = {}
+        for i in keyframe_idx:
+            feats_keyframe[i] = self.edvr(x[:, i:i + num_frames].contiguous())
+        return feats_keyframe
+
+    def forward(self, x):
+        b, n, _, h_input, w_input = x.size()
+
+        x = self.pad_spatial(x)
+        h, w = x.shape[3:]
+
+        keyframe_idx = list(range(0, n, self.keyframe_stride))
+        if keyframe_idx[-1] != n - 1:
+            keyframe_idx.append(n - 1)  # last frame is a keyframe
+
+        # compute flow and keyframe features
+        flows_forward, flows_backward = self.get_flow(x)
+        feats_keyframe = self.get_keyframe_feature(x, keyframe_idx)
+
+        # backward branch
+        out_l = []
+        feat_prop = x.new_zeros(b, self.num_feat, h, w)
+        for i in range(n - 1, -1, -1):
+            x_i = x[:, i, :, :, :]
+            if i < n - 1:
+                flow = flows_backward[:, i, :, :, :]
+                feat_prop = flow_warp(feat_prop, flow.permute(0, 2, 3, 1))
+            if i in keyframe_idx:
+                feat_prop = torch.cat([feat_prop, feats_keyframe[i]], dim=1)
+                feat_prop = self.backward_fusion(feat_prop)
+            feat_prop = torch.cat([x_i, feat_prop], dim=1)
+            feat_prop = self.backward_trunk(feat_prop)
+            out_l.insert(0, feat_prop)
+
+        # forward branch
+        feat_prop = torch.zeros_like(feat_prop)
+        for i in range(0, n):
+            x_i = x[:, i, :, :, :]
+            if i > 0:
+                flow = flows_forward[:, i - 1, :, :, :]
+                feat_prop = flow_warp(feat_prop, flow.permute(0, 2, 3, 1))
+            if i in keyframe_idx:
+                feat_prop = torch.cat([feat_prop, feats_keyframe[i]], dim=1)
+                feat_prop = self.forward_fusion(feat_prop)
+
+            feat_prop = torch.cat([x_i, out_l[i], feat_prop], dim=1)
+            feat_prop = self.forward_trunk(feat_prop)
+
+            # upsample
+            out = self.lrelu(self.pixel_shuffle(self.upconv1(feat_prop)))
+            out = self.lrelu(self.pixel_shuffle(self.upconv2(out)))
+            out = self.lrelu(self.conv_hr(out))
+            out = self.conv_last(out)
+            base = F.interpolate(x_i, scale_factor=4, mode='bilinear', align_corners=False)
+            out += base
+            out_l[i] = out
+
+        return torch.stack(out_l, dim=1)[..., :4 * h_input, :4 * w_input]
+
+
+class EDVRFeatureExtractor(nn.Module):
+    """EDVR feature extractor used in IconVSR.
+
+    Args:
+        num_input_frame (int): Number of input frames.
+        num_feat (int): Number of feature channels
+        load_path (str): Path to the pretrained weights of EDVR. Default: None.
+    """
+
+    def __init__(self, num_input_frame, num_feat, load_path):
+
+        super(EDVRFeatureExtractor, self).__init__()
+
+        self.center_frame_idx = num_input_frame // 2
+
+        # extract pyramid features
+        self.conv_first = nn.Conv2d(3, num_feat, 3, 1, 1)
+        self.feature_extraction = make_layer(ResidualBlockNoBN, 5, num_feat=num_feat)
+        self.conv_l2_1 = nn.Conv2d(num_feat, num_feat, 3, 2, 1)
+        self.conv_l2_2 = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+        self.conv_l3_1 = nn.Conv2d(num_feat, num_feat, 3, 2, 1)
+        self.conv_l3_2 = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+
+        # pcd and tsa module
+        self.pcd_align = PCDAlignment(num_feat=num_feat, deformable_groups=8)
+        self.fusion = TSAFusion(num_feat=num_feat, num_frame=num_input_frame, center_frame_idx=self.center_frame_idx)
+
+        # activation function
+        self.lrelu = nn.LeakyReLU(negative_slope=0.1, inplace=True)
+
+        if load_path:
+            self.load_state_dict(torch.load(load_path, map_location=lambda storage, loc: storage)['params'])
+
+    def forward(self, x):
+        b, n, c, h, w = x.size()
+
+        # extract features for each frame
+        # L1
+        feat_l1 = self.lrelu(self.conv_first(x.view(-1, c, h, w)))
+        feat_l1 = self.feature_extraction(feat_l1)
+        # L2
+        feat_l2 = self.lrelu(self.conv_l2_1(feat_l1))
+        feat_l2 = self.lrelu(self.conv_l2_2(feat_l2))
+        # L3
+        feat_l3 = self.lrelu(self.conv_l3_1(feat_l2))
+        feat_l3 = self.lrelu(self.conv_l3_2(feat_l3))
+
+        feat_l1 = feat_l1.view(b, n, -1, h, w)
+        feat_l2 = feat_l2.view(b, n, -1, h // 2, w // 2)
+        feat_l3 = feat_l3.view(b, n, -1, h // 4, w // 4)
+
+        # PCD alignment
+        ref_feat_l = [  # reference feature list
+            feat_l1[:, self.center_frame_idx, :, :, :].clone(), feat_l2[:, self.center_frame_idx, :, :, :].clone(),
+            feat_l3[:, self.center_frame_idx, :, :, :].clone()
+        ]
+        aligned_feat = []
+        for i in range(n):
+            nbr_feat_l = [  # neighboring feature list
+                feat_l1[:, i, :, :, :].clone(), feat_l2[:, i, :, :, :].clone(), feat_l3[:, i, :, :, :].clone()
+            ]
+            aligned_feat.append(self.pcd_align(nbr_feat_l, ref_feat_l))
+        aligned_feat = torch.stack(aligned_feat, dim=1)  # (b, t, c, h, w)
+
+        # TSA fusion
+        return self.fusion(aligned_feat)

BasicSR/basicsr/archs/basicvsrpp_arch.py

+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+import torchvision
+import warnings
+
+from basicsr.archs.arch_util import flow_warp
+from basicsr.archs.basicvsr_arch import ConvResidualBlocks
+from basicsr.archs.spynet_arch import SpyNet
+from basicsr.ops.dcn import ModulatedDeformConvPack
+from basicsr.utils.registry import ARCH_REGISTRY
+
+
+@ARCH_REGISTRY.register()
+class BasicVSRPlusPlus(nn.Module):
+    """BasicVSR++ network structure.
+
+    Support either x4 upsampling or same size output. Since DCN is used in this
+    model, it can only be used with CUDA enabled. If CUDA is not enabled,
+    feature alignment will be skipped. Besides, we adopt the official DCN
+    implementation and the version of torch need to be higher than 1.9.
+
+    ``Paper: BasicVSR++: Improving Video Super-Resolution with Enhanced Propagation and Alignment``
+
+    Args:
+        mid_channels (int, optional): Channel number of the intermediate
+            features. Default: 64.
+        num_blocks (int, optional): The number of residual blocks in each
+            propagation branch. Default: 7.
+        max_residue_magnitude (int): The maximum magnitude of the offset
+            residue (Eq. 6 in paper). Default: 10.
+        is_low_res_input (bool, optional): Whether the input is low-resolution
+            or not. If False, the output resolution is equal to the input
+            resolution. Default: True.
+        spynet_path (str): Path to the pretrained weights of SPyNet. Default: None.
+        cpu_cache_length (int, optional): When the length of sequence is larger
+            than this value, the intermediate features are sent to CPU. This
+            saves GPU memory, but slows down the inference speed. You can
+            increase this number if you have a GPU with large memory.
+            Default: 100.
+    """
+
+    def __init__(self,
+                 mid_channels=64,
+                 num_blocks=7,
+                 max_residue_magnitude=10,
+                 is_low_res_input=True,
+                 spynet_path=None,
+                 cpu_cache_length=100):
+
+        super().__init__()
+        self.mid_channels = mid_channels
+        self.is_low_res_input = is_low_res_input
+        self.cpu_cache_length = cpu_cache_length
+
+        # optical flow
+        self.spynet = SpyNet(spynet_path)
+
+        # feature extraction module
+        if is_low_res_input:
+            self.feat_extract = ConvResidualBlocks(3, mid_channels, 5)
+        else:
+            self.feat_extract = nn.Sequential(
+                nn.Conv2d(3, mid_channels, 3, 2, 1), nn.LeakyReLU(negative_slope=0.1, inplace=True),
+                nn.Conv2d(mid_channels, mid_channels, 3, 2, 1), nn.LeakyReLU(negative_slope=0.1, inplace=True),
+                ConvResidualBlocks(mid_channels, mid_channels, 5))
+
+        # propagation branches
+        self.deform_align = nn.ModuleDict()
+        self.backbone = nn.ModuleDict()
+        modules = ['backward_1', 'forward_1', 'backward_2', 'forward_2']
+        for i, module in enumerate(modules):
+            if torch.cuda.is_available():
+                self.deform_align[module] = SecondOrderDeformableAlignment(
+                    2 * mid_channels,
+                    mid_channels,
+                    3,
+                    padding=1,
+                    deformable_groups=16,
+                    max_residue_magnitude=max_residue_magnitude)
+            self.backbone[module] = ConvResidualBlocks((2 + i) * mid_channels, mid_channels, num_blocks)
+
+        # upsampling module
+        self.reconstruction = ConvResidualBlocks(5 * mid_channels, mid_channels, 5)
+
+        self.upconv1 = nn.Conv2d(mid_channels, mid_channels * 4, 3, 1, 1, bias=True)
+        self.upconv2 = nn.Conv2d(mid_channels, 64 * 4, 3, 1, 1, bias=True)
+
+        self.pixel_shuffle = nn.PixelShuffle(2)
+
+        self.conv_hr = nn.Conv2d(64, 64, 3, 1, 1)
+        self.conv_last = nn.Conv2d(64, 3, 3, 1, 1)
+        self.img_upsample = nn.Upsample(scale_factor=4, mode='bilinear', align_corners=False)
+
+        # activation function
+        self.lrelu = nn.LeakyReLU(negative_slope=0.1, inplace=True)
+
+        # check if the sequence is augmented by flipping
+        self.is_mirror_extended = False
+
+        if len(self.deform_align) > 0:
+            self.is_with_alignment = True
+        else:
+            self.is_with_alignment = False
+            warnings.warn('Deformable alignment module is not added. '
+                          'Probably your CUDA is not configured correctly. DCN can only '
+                          'be used with CUDA enabled. Alignment is skipped now.')
+
+    def check_if_mirror_extended(self, lqs):
+        """Check whether the input is a mirror-extended sequence.
+
+        If mirror-extended, the i-th (i=0, ..., t-1) frame is equal to the (t-1-i)-th frame.
+
+        Args:
+            lqs (tensor): Input low quality (LQ) sequence with shape (n, t, c, h, w).
+        """
+
+        if lqs.size(1) % 2 == 0:
+            lqs_1, lqs_2 = torch.chunk(lqs, 2, dim=1)
+            if torch.norm(lqs_1 - lqs_2.flip(1)) == 0:
+                self.is_mirror_extended = True
+
+    def compute_flow(self, lqs):
+        """Compute optical flow using SPyNet for feature alignment.
+
+        Note that if the input is an mirror-extended sequence, 'flows_forward'
+        is not needed, since it is equal to 'flows_backward.flip(1)'.
+
+        Args:
+            lqs (tensor): Input low quality (LQ) sequence with
+                shape (n, t, c, h, w).
+
+        Return:
+            tuple(Tensor): Optical flow. 'flows_forward' corresponds to the flows used for forward-time propagation \
+                (current to previous). 'flows_backward' corresponds to the flows used for backward-time \
+                propagation (current to next).
+        """
+
+        n, t, c, h, w = lqs.size()
+        lqs_1 = lqs[:, :-1, :, :, :].reshape(-1, c, h, w)
+        lqs_2 = lqs[:, 1:, :, :, :].reshape(-1, c, h, w)
+
+        flows_backward = self.spynet(lqs_1, lqs_2).view(n, t - 1, 2, h, w)
+
+        if self.is_mirror_extended:  # flows_forward = flows_backward.flip(1)
+            flows_forward = flows_backward.flip(1)
+        else:
+            flows_forward = self.spynet(lqs_2, lqs_1).view(n, t - 1, 2, h, w)
+
+        if self.cpu_cache:
+            flows_backward = flows_backward.cpu()
+            flows_forward = flows_forward.cpu()
+
+        return flows_forward, flows_backward
+
+    def propagate(self, feats, flows, module_name):
+        """Propagate the latent features throughout the sequence.
+
+        Args:
+            feats dict(list[tensor]): Features from previous branches. Each
+                component is a list of tensors with shape (n, c, h, w).
+            flows (tensor): Optical flows with shape (n, t - 1, 2, h, w).
+            module_name (str): The name of the propgation branches. Can either
+                be 'backward_1', 'forward_1', 'backward_2', 'forward_2'.
+
+        Return:
+            dict(list[tensor]): A dictionary containing all the propagated \
+                features. Each key in the dictionary corresponds to a \
+                propagation branch, which is represented by a list of tensors.
+        """
+
+        n, t, _, h, w = flows.size()
+
+        frame_idx = range(0, t + 1)
+        flow_idx = range(-1, t)
+        mapping_idx = list(range(0, len(feats['spatial'])))
+        mapping_idx += mapping_idx[::-1]
+
+        if 'backward' in module_name:
+            frame_idx = frame_idx[::-1]
+            flow_idx = frame_idx
+
+        feat_prop = flows.new_zeros(n, self.mid_channels, h, w)
+        for i, idx in enumerate(frame_idx):
+            feat_current = feats['spatial'][mapping_idx[idx]]
+            if self.cpu_cache:
+                feat_current = feat_current.cuda()
+                feat_prop = feat_prop.cuda()
+            # second-order deformable alignment
+            if i > 0 and self.is_with_alignment:
+                flow_n1 = flows[:, flow_idx[i], :, :, :]
+                if self.cpu_cache:
+                    flow_n1 = flow_n1.cuda()
+
+                cond_n1 = flow_warp(feat_prop, flow_n1.permute(0, 2, 3, 1))
+
+                # initialize second-order features
+                feat_n2 = torch.zeros_like(feat_prop)
+                flow_n2 = torch.zeros_like(flow_n1)
+                cond_n2 = torch.zeros_like(cond_n1)
+
+                if i > 1:  # second-order features
+                    feat_n2 = feats[module_name][-2]
+                    if self.cpu_cache:
+                        feat_n2 = feat_n2.cuda()
+
+                    flow_n2 = flows[:, flow_idx[i - 1], :, :, :]
+                    if self.cpu_cache:
+                        flow_n2 = flow_n2.cuda()
+
+                    flow_n2 = flow_n1 + flow_warp(flow_n2, flow_n1.permute(0, 2, 3, 1))
+                    cond_n2 = flow_warp(feat_n2, flow_n2.permute(0, 2, 3, 1))
+
+                # flow-guided deformable convolution
+                cond = torch.cat([cond_n1, feat_current, cond_n2], dim=1)
+                feat_prop = torch.cat([feat_prop, feat_n2], dim=1)
+                feat_prop = self.deform_align[module_name](feat_prop, cond, flow_n1, flow_n2)
+
+            # concatenate and residual blocks
+            feat = [feat_current] + [feats[k][idx] for k in feats if k not in ['spatial', module_name]] + [feat_prop]
+            if self.cpu_cache:
+                feat = [f.cuda() for f in feat]
+
+            feat = torch.cat(feat, dim=1)
+            feat_prop = feat_prop + self.backbone[module_name](feat)
+            feats[module_name].append(feat_prop)
+
+            if self.cpu_cache:
+                feats[module_name][-1] = feats[module_name][-1].cpu()
+                torch.cuda.empty_cache()
+
+        if 'backward' in module_name:
+            feats[module_name] = feats[module_name][::-1]
+
+        return feats
+
+    def upsample(self, lqs, feats):
+        """Compute the output image given the features.
+
+        Args:
+            lqs (tensor): Input low quality (LQ) sequence with
+                shape (n, t, c, h, w).
+            feats (dict): The features from the propagation branches.
+
+        Returns:
+            Tensor: Output HR sequence with shape (n, t, c, 4h, 4w).
+        """
+
+        outputs = []
+        num_outputs = len(feats['spatial'])
+
+        mapping_idx = list(range(0, num_outputs))
+        mapping_idx += mapping_idx[::-1]
+
+        for i in range(0, lqs.size(1)):
+            hr = [feats[k].pop(0) for k in feats if k != 'spatial']
+            hr.insert(0, feats['spatial'][mapping_idx[i]])
+            hr = torch.cat(hr, dim=1)
+            if self.cpu_cache:
+                hr = hr.cuda()
+
+            hr = self.reconstruction(hr)
+            hr = self.lrelu(self.pixel_shuffle(self.upconv1(hr)))
+            hr = self.lrelu(self.pixel_shuffle(self.upconv2(hr)))
+            hr = self.lrelu(self.conv_hr(hr))
+            hr = self.conv_last(hr)
+            if self.is_low_res_input:
+                hr += self.img_upsample(lqs[:, i, :, :, :])
+            else:
+                hr += lqs[:, i, :, :, :]
+
+            if self.cpu_cache:
+                hr = hr.cpu()
+                torch.cuda.empty_cache()
+
+            outputs.append(hr)
+
+        return torch.stack(outputs, dim=1)
+
+    def forward(self, lqs):
+        """Forward function for BasicVSR++.
+
+        Args:
+            lqs (tensor): Input low quality (LQ) sequence with
+                shape (n, t, c, h, w).
+
+        Returns:
+            Tensor: Output HR sequence with shape (n, t, c, 4h, 4w).
+        """
+
+        n, t, c, h, w = lqs.size()
+
+        # whether to cache the features in CPU
+        self.cpu_cache = True if t > self.cpu_cache_length else False
+
+        if self.is_low_res_input:
+            lqs_downsample = lqs.clone()
+        else:
+            lqs_downsample = F.interpolate(
+                lqs.view(-1, c, h, w), scale_factor=0.25, mode='bicubic').view(n, t, c, h // 4, w // 4)
+
+        # check whether the input is an extended sequence
+        self.check_if_mirror_extended(lqs)
+
+        feats = {}
+        # compute spatial features
+        if self.cpu_cache:
+            feats['spatial'] = []
+            for i in range(0, t):
+                feat = self.feat_extract(lqs[:, i, :, :, :]).cpu()
+                feats['spatial'].append(feat)
+                torch.cuda.empty_cache()
+        else:
+            feats_ = self.feat_extract(lqs.view(-1, c, h, w))
+            h, w = feats_.shape[2:]
+            feats_ = feats_.view(n, t, -1, h, w)
+            feats['spatial'] = [feats_[:, i, :, :, :] for i in range(0, t)]
+
+        # compute optical flow using the low-res inputs
+        assert lqs_downsample.size(3) >= 64 and lqs_downsample.size(4) >= 64, (
+            'The height and width of low-res inputs must be at least 64, '
+            f'but got {h} and {w}.')
+        flows_forward, flows_backward = self.compute_flow(lqs_downsample)
+
+        # feature propgation
+        for iter_ in [1, 2]:
+            for direction in ['backward', 'forward']:
+                module = f'{direction}_{iter_}'
+
+                feats[module] = []
+
+                if direction == 'backward':
+                    flows = flows_backward
+                elif flows_forward is not None:
+                    flows = flows_forward
+                else:
+                    flows = flows_backward.flip(1)
+
+                feats = self.propagate(feats, flows, module)
+                if self.cpu_cache:
+                    del flows
+                    torch.cuda.empty_cache()
+
+        return self.upsample(lqs, feats)
+
+
+class SecondOrderDeformableAlignment(ModulatedDeformConvPack):
+    """Second-order deformable alignment module.
+
+    Args:
+        in_channels (int): Same as nn.Conv2d.
+        out_channels (int): Same as nn.Conv2d.
+        kernel_size (int or tuple[int]): Same as nn.Conv2d.
+        stride (int or tuple[int]): Same as nn.Conv2d.
+        padding (int or tuple[int]): Same as nn.Conv2d.
+        dilation (int or tuple[int]): Same as nn.Conv2d.
+        groups (int): Same as nn.Conv2d.
+        bias (bool or str): If specified as `auto`, it will be decided by the
+            norm_cfg. Bias will be set as True if norm_cfg is None, otherwise
+            False.
+        max_residue_magnitude (int): The maximum magnitude of the offset
+            residue (Eq. 6 in paper). Default: 10.
+    """
+
+    def __init__(self, *args, **kwargs):
+        self.max_residue_magnitude = kwargs.pop('max_residue_magnitude', 10)
+
+        super(SecondOrderDeformableAlignment, self).__init__(*args, **kwargs)
+
+        self.conv_offset = nn.Sequential(
+            nn.Conv2d(3 * self.out_channels + 4, self.out_channels, 3, 1, 1),
+            nn.LeakyReLU(negative_slope=0.1, inplace=True),
+            nn.Conv2d(self.out_channels, self.out_channels, 3, 1, 1),
+            nn.LeakyReLU(negative_slope=0.1, inplace=True),
+            nn.Conv2d(self.out_channels, self.out_channels, 3, 1, 1),
+            nn.LeakyReLU(negative_slope=0.1, inplace=True),
+            nn.Conv2d(self.out_channels, 27 * self.deformable_groups, 3, 1, 1),
+        )
+
+        self.init_offset()
+
+    def init_offset(self):
+
+        def _constant_init(module, val, bias=0):
+            if hasattr(module, 'weight') and module.weight is not None:
+                nn.init.constant_(module.weight, val)
+            if hasattr(module, 'bias') and module.bias is not None:
+                nn.init.constant_(module.bias, bias)
+
+        _constant_init(self.conv_offset[-1], val=0, bias=0)
+
+    def forward(self, x, extra_feat, flow_1, flow_2):
+        extra_feat = torch.cat([extra_feat, flow_1, flow_2], dim=1)
+        out = self.conv_offset(extra_feat)
+        o1, o2, mask = torch.chunk(out, 3, dim=1)
+
+        # offset
+        offset = self.max_residue_magnitude * torch.tanh(torch.cat((o1, o2), dim=1))
+        offset_1, offset_2 = torch.chunk(offset, 2, dim=1)
+        offset_1 = offset_1 + flow_1.flip(1).repeat(1, offset_1.size(1) // 2, 1, 1)
+        offset_2 = offset_2 + flow_2.flip(1).repeat(1, offset_2.size(1) // 2, 1, 1)
+        offset = torch.cat([offset_1, offset_2], dim=1)
+
+        # mask
+        mask = torch.sigmoid(mask)
+
+        return torchvision.ops.deform_conv2d(x, offset, self.weight, self.bias, self.stride, self.padding,
+                                             self.dilation, mask)
+
+
+# if __name__ == '__main__':
+#     spynet_path = 'experiments/pretrained_models/flownet/spynet_sintel_final-3d2a1287.pth'
+#     model = BasicVSRPlusPlus(spynet_path=spynet_path).cuda()
+#     input = torch.rand(1, 2, 3, 64, 64).cuda()
+#     output = model(input)
+#     print('===================')
+#     print(output.shape)

BasicSR/basicsr/archs/dfdnet_arch.py

+import numpy as np
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+from torch.nn.utils.spectral_norm import spectral_norm
+
+from basicsr.utils.registry import ARCH_REGISTRY
+from .dfdnet_util import AttentionBlock, Blur, MSDilationBlock, UpResBlock, adaptive_instance_normalization
+from .vgg_arch import VGGFeatureExtractor
+
+
+class SFTUpBlock(nn.Module):
+    """Spatial feature transform (SFT) with upsampling block.
+
+    Args:
+        in_channel (int): Number of input channels.
+        out_channel (int): Number of output channels.
+        kernel_size (int): Kernel size in convolutions. Default: 3.
+        padding (int): Padding in convolutions. Default: 1.
+    """
+
+    def __init__(self, in_channel, out_channel, kernel_size=3, padding=1):
+        super(SFTUpBlock, self).__init__()
+        self.conv1 = nn.Sequential(
+            Blur(in_channel),
+            spectral_norm(nn.Conv2d(in_channel, out_channel, kernel_size, padding=padding)),
+            nn.LeakyReLU(0.04, True),
+            # The official codes use two LeakyReLU here, so 0.04 for equivalent
+        )
+        self.convup = nn.Sequential(
+            nn.Upsample(scale_factor=2, mode='bilinear', align_corners=False),
+            spectral_norm(nn.Conv2d(out_channel, out_channel, kernel_size, padding=padding)),
+            nn.LeakyReLU(0.2, True),
+        )
+
+        # for SFT scale and shift
+        self.scale_block = nn.Sequential(
+            spectral_norm(nn.Conv2d(in_channel, out_channel, 3, 1, 1)), nn.LeakyReLU(0.2, True),
+            spectral_norm(nn.Conv2d(out_channel, out_channel, 3, 1, 1)))
+        self.shift_block = nn.Sequential(
+            spectral_norm(nn.Conv2d(in_channel, out_channel, 3, 1, 1)), nn.LeakyReLU(0.2, True),
+            spectral_norm(nn.Conv2d(out_channel, out_channel, 3, 1, 1)), nn.Sigmoid())
+        # The official codes use sigmoid for shift block, do not know why
+
+    def forward(self, x, updated_feat):
+        out = self.conv1(x)
+        # SFT
+        scale = self.scale_block(updated_feat)
+        shift = self.shift_block(updated_feat)
+        out = out * scale + shift
+        # upsample
+        out = self.convup(out)
+        return out
+
+
+@ARCH_REGISTRY.register()
+class DFDNet(nn.Module):
+    """DFDNet: Deep Face Dictionary Network.
+
+    It only processes faces with 512x512 size.
+
+    Args:
+        num_feat (int): Number of feature channels.
+        dict_path (str): Path to the facial component dictionary.
+    """
+
+    def __init__(self, num_feat, dict_path):
+        super().__init__()
+        self.parts = ['left_eye', 'right_eye', 'nose', 'mouth']
+        # part_sizes: [80, 80, 50, 110]
+        channel_sizes = [128, 256, 512, 512]
+        self.feature_sizes = np.array([256, 128, 64, 32])
+        self.vgg_layers = ['relu2_2', 'relu3_4', 'relu4_4', 'conv5_4']
+        self.flag_dict_device = False
+
+        # dict
+        self.dict = torch.load(dict_path)
+
+        # vgg face extractor
+        self.vgg_extractor = VGGFeatureExtractor(
+            layer_name_list=self.vgg_layers,
+            vgg_type='vgg19',
+            use_input_norm=True,
+            range_norm=True,
+            requires_grad=False)
+
+        # attention block for fusing dictionary features and input features
+        self.attn_blocks = nn.ModuleDict()
+        for idx, feat_size in enumerate(self.feature_sizes):
+            for name in self.parts:
+                self.attn_blocks[f'{name}_{feat_size}'] = AttentionBlock(channel_sizes[idx])
+
+        # multi scale dilation block
+        self.multi_scale_dilation = MSDilationBlock(num_feat * 8, dilation=[4, 3, 2, 1])
+
+        # upsampling and reconstruction
+        self.upsample0 = SFTUpBlock(num_feat * 8, num_feat * 8)
+        self.upsample1 = SFTUpBlock(num_feat * 8, num_feat * 4)
+        self.upsample2 = SFTUpBlock(num_feat * 4, num_feat * 2)
+        self.upsample3 = SFTUpBlock(num_feat * 2, num_feat)
+        self.upsample4 = nn.Sequential(
+            spectral_norm(nn.Conv2d(num_feat, num_feat, 3, 1, 1)), nn.LeakyReLU(0.2, True), UpResBlock(num_feat),
+            UpResBlock(num_feat), nn.Conv2d(num_feat, 3, kernel_size=3, stride=1, padding=1), nn.Tanh())
+
+    def swap_feat(self, vgg_feat, updated_feat, dict_feat, location, part_name, f_size):
+        """swap the features from the dictionary."""
+        # get the original vgg features
+        part_feat = vgg_feat[:, :, location[1]:location[3], location[0]:location[2]].clone()
+        # resize original vgg features
+        part_resize_feat = F.interpolate(part_feat, dict_feat.size()[2:4], mode='bilinear', align_corners=False)
+        # use adaptive instance normalization to adjust color and illuminations
+        dict_feat = adaptive_instance_normalization(dict_feat, part_resize_feat)
+        # get similarity scores
+        similarity_score = F.conv2d(part_resize_feat, dict_feat)
+        similarity_score = F.softmax(similarity_score.view(-1), dim=0)
+        # select the most similar features in the dict (after norm)
+        select_idx = torch.argmax(similarity_score)
+        swap_feat = F.interpolate(dict_feat[select_idx:select_idx + 1], part_feat.size()[2:4])
+        # attention
+        attn = self.attn_blocks[f'{part_name}_' + str(f_size)](swap_feat - part_feat)
+        attn_feat = attn * swap_feat
+        # update features
+        updated_feat[:, :, location[1]:location[3], location[0]:location[2]] = attn_feat + part_feat
+        return updated_feat
+
+    def put_dict_to_device(self, x):
+        if self.flag_dict_device is False:
+            for k, v in self.dict.items():
+                for kk, vv in v.items():
+                    self.dict[k][kk] = vv.to(x)
+            self.flag_dict_device = True
+
+    def forward(self, x, part_locations):
+        """
+        Now only support testing with batch size = 0.
+
+        Args:
+            x (Tensor): Input faces with shape (b, c, 512, 512).
+            part_locations (list[Tensor]): Part locations.
+        """
+        self.put_dict_to_device(x)
+        # extract vggface features
+        vgg_features = self.vgg_extractor(x)
+        # update vggface features using the dictionary for each part
+        updated_vgg_features = []
+        batch = 0  # only supports testing with batch size = 0
+        for vgg_layer, f_size in zip(self.vgg_layers, self.feature_sizes):
+            dict_features = self.dict[f'{f_size}']
+            vgg_feat = vgg_features[vgg_layer]
+            updated_feat = vgg_feat.clone()
+
+            # swap features from dictionary
+            for part_idx, part_name in enumerate(self.parts):
+                location = (part_locations[part_idx][batch] // (512 / f_size)).int()
+                updated_feat = self.swap_feat(vgg_feat, updated_feat, dict_features[part_name], location, part_name,
+                                              f_size)
+
+            updated_vgg_features.append(updated_feat)
+
+        vgg_feat_dilation = self.multi_scale_dilation(vgg_features['conv5_4'])
+        # use updated vgg features to modulate the upsampled features with
+        # SFT (Spatial Feature Transform) scaling and shifting manner.
+        upsampled_feat = self.upsample0(vgg_feat_dilation, updated_vgg_features[3])
+        upsampled_feat = self.upsample1(upsampled_feat, updated_vgg_features[2])
+        upsampled_feat = self.upsample2(upsampled_feat, updated_vgg_features[1])
+        upsampled_feat = self.upsample3(upsampled_feat, updated_vgg_features[0])
+        out = self.upsample4(upsampled_feat)
+
+        return out

BasicSR/basicsr/archs/dfdnet_util.py

+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+from torch.autograd import Function
+from torch.nn.utils.spectral_norm import spectral_norm
+
+
+class BlurFunctionBackward(Function):
+
+    @staticmethod
+    def forward(ctx, grad_output, kernel, kernel_flip):
+        ctx.save_for_backward(kernel, kernel_flip)
+        grad_input = F.conv2d(grad_output, kernel_flip, padding=1, groups=grad_output.shape[1])
+        return grad_input
+
+    @staticmethod
+    def backward(ctx, gradgrad_output):
+        kernel, _ = ctx.saved_tensors
+        grad_input = F.conv2d(gradgrad_output, kernel, padding=1, groups=gradgrad_output.shape[1])
+        return grad_input, None, None
+
+
+class BlurFunction(Function):
+
+    @staticmethod
+    def forward(ctx, x, kernel, kernel_flip):
+        ctx.save_for_backward(kernel, kernel_flip)
+        output = F.conv2d(x, kernel, padding=1, groups=x.shape[1])
+        return output
+
+    @staticmethod
+    def backward(ctx, grad_output):
+        kernel, kernel_flip = ctx.saved_tensors
+        grad_input = BlurFunctionBackward.apply(grad_output, kernel, kernel_flip)
+        return grad_input, None, None
+
+
+blur = BlurFunction.apply
+
+
+class Blur(nn.Module):
+
+    def __init__(self, channel):
+        super().__init__()
+        kernel = torch.tensor([[1, 2, 1], [2, 4, 2], [1, 2, 1]], dtype=torch.float32)
+        kernel = kernel.view(1, 1, 3, 3)
+        kernel = kernel / kernel.sum()
+        kernel_flip = torch.flip(kernel, [2, 3])
+
+        self.kernel = kernel.repeat(channel, 1, 1, 1)
+        self.kernel_flip = kernel_flip.repeat(channel, 1, 1, 1)
+
+    def forward(self, x):
+        return blur(x, self.kernel.type_as(x), self.kernel_flip.type_as(x))
+
+
+def calc_mean_std(feat, eps=1e-5):
+    """Calculate mean and std for adaptive_instance_normalization.
+
+    Args:
+        feat (Tensor): 4D tensor.
+        eps (float): A small value added to the variance to avoid
+            divide-by-zero. Default: 1e-5.
+    """
+    size = feat.size()
+    assert len(size) == 4, 'The input feature should be 4D tensor.'
+    n, c = size[:2]
+    feat_var = feat.view(n, c, -1).var(dim=2) + eps
+    feat_std = feat_var.sqrt().view(n, c, 1, 1)
+    feat_mean = feat.view(n, c, -1).mean(dim=2).view(n, c, 1, 1)
+    return feat_mean, feat_std
+
+
+def adaptive_instance_normalization(content_feat, style_feat):
+    """Adaptive instance normalization.
+
+    Adjust the reference features to have the similar color and illuminations
+    as those in the degradate features.
+
+    Args:
+        content_feat (Tensor): The reference feature.
+        style_feat (Tensor): The degradate features.
+    """
+    size = content_feat.size()
+    style_mean, style_std = calc_mean_std(style_feat)
+    content_mean, content_std = calc_mean_std(content_feat)
+    normalized_feat = (content_feat - content_mean.expand(size)) / content_std.expand(size)
+    return normalized_feat * style_std.expand(size) + style_mean.expand(size)
+
+
+def AttentionBlock(in_channel):
+    return nn.Sequential(
+        spectral_norm(nn.Conv2d(in_channel, in_channel, 3, 1, 1)), nn.LeakyReLU(0.2, True),
+        spectral_norm(nn.Conv2d(in_channel, in_channel, 3, 1, 1)))
+
+
+def conv_block(in_channels, out_channels, kernel_size=3, stride=1, dilation=1, bias=True):
+    """Conv block used in MSDilationBlock."""
+
+    return nn.Sequential(
+        spectral_norm(
+            nn.Conv2d(
+                in_channels,
+                out_channels,
+                kernel_size=kernel_size,
+                stride=stride,
+                dilation=dilation,
+                padding=((kernel_size - 1) // 2) * dilation,
+                bias=bias)),
+        nn.LeakyReLU(0.2),
+        spectral_norm(
+            nn.Conv2d(
+                out_channels,
+                out_channels,
+                kernel_size=kernel_size,
+                stride=stride,
+                dilation=dilation,
+                padding=((kernel_size - 1) // 2) * dilation,
+                bias=bias)),
+    )
+
+
+class MSDilationBlock(nn.Module):
+    """Multi-scale dilation block."""
+
+    def __init__(self, in_channels, kernel_size=3, dilation=(1, 1, 1, 1), bias=True):
+        super(MSDilationBlock, self).__init__()
+
+        self.conv_blocks = nn.ModuleList()
+        for i in range(4):
+            self.conv_blocks.append(conv_block(in_channels, in_channels, kernel_size, dilation=dilation[i], bias=bias))
+        self.conv_fusion = spectral_norm(
+            nn.Conv2d(
+                in_channels * 4,
+                in_channels,
+                kernel_size=kernel_size,
+                stride=1,
+                padding=(kernel_size - 1) // 2,
+                bias=bias))
+
+    def forward(self, x):
+        out = []
+        for i in range(4):
+            out.append(self.conv_blocks[i](x))
+        out = torch.cat(out, 1)
+        out = self.conv_fusion(out) + x
+        return out
+
+
+class UpResBlock(nn.Module):
+
+    def __init__(self, in_channel):
+        super(UpResBlock, self).__init__()
+        self.body = nn.Sequential(
+            nn.Conv2d(in_channel, in_channel, 3, 1, 1),
+            nn.LeakyReLU(0.2, True),
+            nn.Conv2d(in_channel, in_channel, 3, 1, 1),
+        )
+
+    def forward(self, x):
+        out = x + self.body(x)
+        return out

BasicSR/basicsr/archs/discriminator_arch.py

+from torch import nn as nn
+from torch.nn import functional as F
+from torch.nn.utils import spectral_norm
+
+from basicsr.utils.registry import ARCH_REGISTRY
+
+
+@ARCH_REGISTRY.register()
+class VGGStyleDiscriminator(nn.Module):
+    """VGG style discriminator with input size 128 x 128 or 256 x 256.
+
+    It is used to train SRGAN, ESRGAN, and VideoGAN.
+
+    Args:
+        num_in_ch (int): Channel number of inputs. Default: 3.
+        num_feat (int): Channel number of base intermediate features.Default: 64.
+    """
+
+    def __init__(self, num_in_ch, num_feat, input_size=128):
+        super(VGGStyleDiscriminator, self).__init__()
+        self.input_size = input_size
+        assert self.input_size == 128 or self.input_size == 256, (
+            f'input size must be 128 or 256, but received {input_size}')
+
+        self.conv0_0 = nn.Conv2d(num_in_ch, num_feat, 3, 1, 1, bias=True)
+        self.conv0_1 = nn.Conv2d(num_feat, num_feat, 4, 2, 1, bias=False)
+        self.bn0_1 = nn.BatchNorm2d(num_feat, affine=True)
+
+        self.conv1_0 = nn.Conv2d(num_feat, num_feat * 2, 3, 1, 1, bias=False)
+        self.bn1_0 = nn.BatchNorm2d(num_feat * 2, affine=True)
+        self.conv1_1 = nn.Conv2d(num_feat * 2, num_feat * 2, 4, 2, 1, bias=False)
+        self.bn1_1 = nn.BatchNorm2d(num_feat * 2, affine=True)
+
+        self.conv2_0 = nn.Conv2d(num_feat * 2, num_feat * 4, 3, 1, 1, bias=False)
+        self.bn2_0 = nn.BatchNorm2d(num_feat * 4, affine=True)
+        self.conv2_1 = nn.Conv2d(num_feat * 4, num_feat * 4, 4, 2, 1, bias=False)
+        self.bn2_1 = nn.BatchNorm2d(num_feat * 4, affine=True)
+
+        self.conv3_0 = nn.Conv2d(num_feat * 4, num_feat * 8, 3, 1, 1, bias=False)
+        self.bn3_0 = nn.BatchNorm2d(num_feat * 8, affine=True)
+        self.conv3_1 = nn.Conv2d(num_feat * 8, num_feat * 8, 4, 2, 1, bias=False)
+        self.bn3_1 = nn.BatchNorm2d(num_feat * 8, affine=True)
+
+        self.conv4_0 = nn.Conv2d(num_feat * 8, num_feat * 8, 3, 1, 1, bias=False)
+        self.bn4_0 = nn.BatchNorm2d(num_feat * 8, affine=True)
+        self.conv4_1 = nn.Conv2d(num_feat * 8, num_feat * 8, 4, 2, 1, bias=False)
+        self.bn4_1 = nn.BatchNorm2d(num_feat * 8, affine=True)
+
+        if self.input_size == 256:
+            self.conv5_0 = nn.Conv2d(num_feat * 8, num_feat * 8, 3, 1, 1, bias=False)
+            self.bn5_0 = nn.BatchNorm2d(num_feat * 8, affine=True)
+            self.conv5_1 = nn.Conv2d(num_feat * 8, num_feat * 8, 4, 2, 1, bias=False)
+            self.bn5_1 = nn.BatchNorm2d(num_feat * 8, affine=True)
+
+        self.linear1 = nn.Linear(num_feat * 8 * 4 * 4, 100)
+        self.linear2 = nn.Linear(100, 1)
+
+        # activation function
+        self.lrelu = nn.LeakyReLU(negative_slope=0.2, inplace=True)
+
+    def forward(self, x):
+        assert x.size(2) == self.input_size, (f'Input size must be identical to input_size, but received {x.size()}.')
+
+        feat = self.lrelu(self.conv0_0(x))
+        feat = self.lrelu(self.bn0_1(self.conv0_1(feat)))  # output spatial size: /2
+
+        feat = self.lrelu(self.bn1_0(self.conv1_0(feat)))
+        feat = self.lrelu(self.bn1_1(self.conv1_1(feat)))  # output spatial size: /4
+
+        feat = self.lrelu(self.bn2_0(self.conv2_0(feat)))
+        feat = self.lrelu(self.bn2_1(self.conv2_1(feat)))  # output spatial size: /8
+
+        feat = self.lrelu(self.bn3_0(self.conv3_0(feat)))
+        feat = self.lrelu(self.bn3_1(self.conv3_1(feat)))  # output spatial size: /16
+
+        feat = self.lrelu(self.bn4_0(self.conv4_0(feat)))
+        feat = self.lrelu(self.bn4_1(self.conv4_1(feat)))  # output spatial size: /32
+
+        if self.input_size == 256:
+            feat = self.lrelu(self.bn5_0(self.conv5_0(feat)))
+            feat = self.lrelu(self.bn5_1(self.conv5_1(feat)))  # output spatial size: / 64
+
+        # spatial size: (4, 4)
+        feat = feat.view(feat.size(0), -1)
+        feat = self.lrelu(self.linear1(feat))
+        out = self.linear2(feat)
+        return out
+
+
+@ARCH_REGISTRY.register(suffix='basicsr')
+class UNetDiscriminatorSN(nn.Module):
+    """Defines a U-Net discriminator with spectral normalization (SN)
+
+    It is used in Real-ESRGAN: Training Real-World Blind Super-Resolution with Pure Synthetic Data.
+
+    Arg:
+        num_in_ch (int): Channel number of inputs. Default: 3.
+        num_feat (int): Channel number of base intermediate features. Default: 64.
+        skip_connection (bool): Whether to use skip connections between U-Net. Default: True.
+    """
+
+    def __init__(self, num_in_ch, num_feat=64, skip_connection=True):
+        super(UNetDiscriminatorSN, self).__init__()
+        self.skip_connection = skip_connection
+        norm = spectral_norm
+        # the first convolution
+        self.conv0 = nn.Conv2d(num_in_ch, num_feat, kernel_size=3, stride=1, padding=1)
+        # downsample
+        self.conv1 = norm(nn.Conv2d(num_feat, num_feat * 2, 4, 2, 1, bias=False))
+        self.conv2 = norm(nn.Conv2d(num_feat * 2, num_feat * 4, 4, 2, 1, bias=False))
+        self.conv3 = norm(nn.Conv2d(num_feat * 4, num_feat * 8, 4, 2, 1, bias=False))
+        # upsample
+        self.conv4 = norm(nn.Conv2d(num_feat * 8, num_feat * 4, 3, 1, 1, bias=False))
+        self.conv5 = norm(nn.Conv2d(num_feat * 4, num_feat * 2, 3, 1, 1, bias=False))
+        self.conv6 = norm(nn.Conv2d(num_feat * 2, num_feat, 3, 1, 1, bias=False))
+        # extra convolutions
+        self.conv7 = norm(nn.Conv2d(num_feat, num_feat, 3, 1, 1, bias=False))
+        self.conv8 = norm(nn.Conv2d(num_feat, num_feat, 3, 1, 1, bias=False))
+        self.conv9 = nn.Conv2d(num_feat, 1, 3, 1, 1)
+
+    def forward(self, x):
+        # downsample
+        x0 = F.leaky_relu(self.conv0(x), negative_slope=0.2, inplace=True)
+        x1 = F.leaky_relu(self.conv1(x0), negative_slope=0.2, inplace=True)
+        x2 = F.leaky_relu(self.conv2(x1), negative_slope=0.2, inplace=True)
+        x3 = F.leaky_relu(self.conv3(x2), negative_slope=0.2, inplace=True)
+
+        # upsample
+        x3 = F.interpolate(x3, scale_factor=2, mode='bilinear', align_corners=False)
+        x4 = F.leaky_relu(self.conv4(x3), negative_slope=0.2, inplace=True)
+
+        if self.skip_connection:
+            x4 = x4 + x2
+        x4 = F.interpolate(x4, scale_factor=2, mode='bilinear', align_corners=False)
+        x5 = F.leaky_relu(self.conv5(x4), negative_slope=0.2, inplace=True)
+
+        if self.skip_connection:
+            x5 = x5 + x1
+        x5 = F.interpolate(x5, scale_factor=2, mode='bilinear', align_corners=False)
+        x6 = F.leaky_relu(self.conv6(x5), negative_slope=0.2, inplace=True)
+
+        if self.skip_connection:
+            x6 = x6 + x0
+
+        # extra convolutions
+        out = F.leaky_relu(self.conv7(x6), negative_slope=0.2, inplace=True)
+        out = F.leaky_relu(self.conv8(out), negative_slope=0.2, inplace=True)
+        out = self.conv9(out)
+
+        return out

BasicSR/basicsr/archs/duf_arch.py

+import numpy as np
+import torch
+from torch import nn as nn
+from torch.nn import functional as F
+
+from basicsr.utils.registry import ARCH_REGISTRY
+
+
+class DenseBlocksTemporalReduce(nn.Module):
+    """A concatenation of 3 dense blocks with reduction in temporal dimension.
+
+    Note that the output temporal dimension is 6 fewer the input temporal dimension, since there are 3 blocks.
+
+    Args:
+        num_feat (int): Number of channels in the blocks. Default: 64.
+        num_grow_ch (int): Growing factor of the dense blocks. Default: 32
+        adapt_official_weights (bool): Whether to adapt the weights translated from the official implementation.
+            Set to false if you want to train from scratch. Default: False.
+    """
+
+    def __init__(self, num_feat=64, num_grow_ch=32, adapt_official_weights=False):
+        super(DenseBlocksTemporalReduce, self).__init__()
+        if adapt_official_weights:
+            eps = 1e-3
+            momentum = 1e-3
+        else:  # pytorch default values
+            eps = 1e-05
+            momentum = 0.1
+
+        self.temporal_reduce1 = nn.Sequential(
+            nn.BatchNorm3d(num_feat, eps=eps, momentum=momentum), nn.ReLU(inplace=True),
+            nn.Conv3d(num_feat, num_feat, (1, 1, 1), stride=(1, 1, 1), padding=(0, 0, 0), bias=True),
+            nn.BatchNorm3d(num_feat, eps=eps, momentum=momentum), nn.ReLU(inplace=True),
+            nn.Conv3d(num_feat, num_grow_ch, (3, 3, 3), stride=(1, 1, 1), padding=(0, 1, 1), bias=True))
+
+        self.temporal_reduce2 = nn.Sequential(
+            nn.BatchNorm3d(num_feat + num_grow_ch, eps=eps, momentum=momentum), nn.ReLU(inplace=True),
+            nn.Conv3d(
+                num_feat + num_grow_ch,
+                num_feat + num_grow_ch, (1, 1, 1),
+                stride=(1, 1, 1),
+                padding=(0, 0, 0),
+                bias=True), nn.BatchNorm3d(num_feat + num_grow_ch, eps=eps, momentum=momentum), nn.ReLU(inplace=True),
+            nn.Conv3d(num_feat + num_grow_ch, num_grow_ch, (3, 3, 3), stride=(1, 1, 1), padding=(0, 1, 1), bias=True))
+
+        self.temporal_reduce3 = nn.Sequential(
+            nn.BatchNorm3d(num_feat + 2 * num_grow_ch, eps=eps, momentum=momentum), nn.ReLU(inplace=True),
+            nn.Conv3d(
+                num_feat + 2 * num_grow_ch,
+                num_feat + 2 * num_grow_ch, (1, 1, 1),
+                stride=(1, 1, 1),
+                padding=(0, 0, 0),
+                bias=True), nn.BatchNorm3d(num_feat + 2 * num_grow_ch, eps=eps, momentum=momentum),
+            nn.ReLU(inplace=True),
+            nn.Conv3d(
+                num_feat + 2 * num_grow_ch, num_grow_ch, (3, 3, 3), stride=(1, 1, 1), padding=(0, 1, 1), bias=True))
+
+    def forward(self, x):
+        """
+        Args:
+            x (Tensor): Input tensor with shape (b, num_feat, t, h, w).
+
+        Returns:
+            Tensor: Output with shape (b, num_feat + num_grow_ch * 3, 1, h, w).
+        """
+        x1 = self.temporal_reduce1(x)
+        x1 = torch.cat((x[:, :, 1:-1, :, :], x1), 1)
+
+        x2 = self.temporal_reduce2(x1)
+        x2 = torch.cat((x1[:, :, 1:-1, :, :], x2), 1)
+
+        x3 = self.temporal_reduce3(x2)
+        x3 = torch.cat((x2[:, :, 1:-1, :, :], x3), 1)
+
+        return x3
+
+
+class DenseBlocks(nn.Module):
+    """ A concatenation of N dense blocks.
+
+    Args:
+        num_feat (int): Number of channels in the blocks. Default: 64.
+        num_grow_ch (int): Growing factor of the dense blocks. Default: 32.
+        num_block (int): Number of dense blocks. The values are:
+            DUF-S (16 layers): 3
+            DUF-M (18 layers): 9
+            DUF-L (52 layers): 21
+        adapt_official_weights (bool): Whether to adapt the weights translated from the official implementation.
+            Set to false if you want to train from scratch. Default: False.
+    """
+
+    def __init__(self, num_block, num_feat=64, num_grow_ch=16, adapt_official_weights=False):
+        super(DenseBlocks, self).__init__()
+        if adapt_official_weights:
+            eps = 1e-3
+            momentum = 1e-3
+        else:  # pytorch default values
+            eps = 1e-05
+            momentum = 0.1
+
+        self.dense_blocks = nn.ModuleList()
+        for i in range(0, num_block):
+            self.dense_blocks.append(
+                nn.Sequential(
+                    nn.BatchNorm3d(num_feat + i * num_grow_ch, eps=eps, momentum=momentum), nn.ReLU(inplace=True),
+                    nn.Conv3d(
+                        num_feat + i * num_grow_ch,
+                        num_feat + i * num_grow_ch, (1, 1, 1),
+                        stride=(1, 1, 1),
+                        padding=(0, 0, 0),
+                        bias=True), nn.BatchNorm3d(num_feat + i * num_grow_ch, eps=eps, momentum=momentum),
+                    nn.ReLU(inplace=True),
+                    nn.Conv3d(
+                        num_feat + i * num_grow_ch,
+                        num_grow_ch, (3, 3, 3),
+                        stride=(1, 1, 1),
+                        padding=(1, 1, 1),
+                        bias=True)))
+
+    def forward(self, x):
+        """
+        Args:
+            x (Tensor): Input tensor with shape (b, num_feat, t, h, w).
+
+        Returns:
+            Tensor: Output with shape (b, num_feat + num_block * num_grow_ch, t, h, w).
+        """
+        for i in range(0, len(self.dense_blocks)):
+            y = self.dense_blocks[i](x)
+            x = torch.cat((x, y), 1)
+        return x
+
+
+class DynamicUpsamplingFilter(nn.Module):
+    """Dynamic upsampling filter used in DUF.
+
+    Reference: https://github.com/yhjo09/VSR-DUF
+
+    It only supports input with 3 channels. And it applies the same filters to 3 channels.
+
+    Args:
+        filter_size (tuple): Filter size of generated filters. The shape is (kh, kw). Default: (5, 5).
+    """
+
+    def __init__(self, filter_size=(5, 5)):
+        super(DynamicUpsamplingFilter, self).__init__()
+        if not isinstance(filter_size, tuple):
+            raise TypeError(f'The type of filter_size must be tuple, but got type{filter_size}')
+        if len(filter_size) != 2:
+            raise ValueError(f'The length of filter size must be 2, but got {len(filter_size)}.')
+        # generate a local expansion filter, similar to im2col
+        self.filter_size = filter_size
+        filter_prod = np.prod(filter_size)
+        expansion_filter = torch.eye(int(filter_prod)).view(filter_prod, 1, *filter_size)  # (kh*kw, 1, kh, kw)
+        self.expansion_filter = expansion_filter.repeat(3, 1, 1, 1)  # repeat for all the 3 channels
+
+    def forward(self, x, filters):
+        """Forward function for DynamicUpsamplingFilter.
+
+        Args:
+            x (Tensor): Input image with 3 channels. The shape is (n, 3, h, w).
+            filters (Tensor): Generated dynamic filters. The shape is (n, filter_prod, upsampling_square, h, w).
+                filter_prod: prod of filter kernel size, e.g., 1*5*5=25.
+                upsampling_square: similar to pixel shuffle, upsampling_square = upsampling * upsampling.
+                e.g., for x 4 upsampling, upsampling_square= 4*4 = 16
+
+        Returns:
+            Tensor: Filtered image with shape (n, 3*upsampling_square, h, w)
+        """
+        n, filter_prod, upsampling_square, h, w = filters.size()
+        kh, kw = self.filter_size
+        expanded_input = F.conv2d(
+            x, self.expansion_filter.to(x), padding=(kh // 2, kw // 2), groups=3)  # (n, 3*filter_prod, h, w)
+        expanded_input = expanded_input.view(n, 3, filter_prod, h, w).permute(0, 3, 4, 1,
+                                                                              2)  # (n, h, w, 3, filter_prod)
+        filters = filters.permute(0, 3, 4, 1, 2)  # (n, h, w, filter_prod, upsampling_square]
+        out = torch.matmul(expanded_input, filters)  # (n, h, w, 3, upsampling_square)
+        return out.permute(0, 3, 4, 1, 2).view(n, 3 * upsampling_square, h, w)
+
+
+@ARCH_REGISTRY.register()
+class DUF(nn.Module):
+    """Network architecture for DUF
+
+    ``Paper: Deep Video Super-Resolution Network Using Dynamic Upsampling Filters Without Explicit Motion Compensation``
+
+    Reference: https://github.com/yhjo09/VSR-DUF
+
+    For all the models below, 'adapt_official_weights' is only necessary when
+    loading the weights converted from the official TensorFlow weights.
+    Please set it to False if you are training the model from scratch.
+
+    There are three models with different model size: DUF16Layers, DUF28Layers,
+    and DUF52Layers. This class is the base class for these models.
+
+    Args:
+        scale (int): The upsampling factor. Default: 4.
+        num_layer (int): The number of layers. Default: 52.
+        adapt_official_weights_weights (bool): Whether to adapt the weights
+            translated from the official implementation. Set to false if you
+            want to train from scratch. Default: False.
+    """
+
+    def __init__(self, scale=4, num_layer=52, adapt_official_weights=False):
+        super(DUF, self).__init__()
+        self.scale = scale
+        if adapt_official_weights:
+            eps = 1e-3
+            momentum = 1e-3
+        else:  # pytorch default values
+            eps = 1e-05
+            momentum = 0.1
+
+        self.conv3d1 = nn.Conv3d(3, 64, (1, 3, 3), stride=(1, 1, 1), padding=(0, 1, 1), bias=True)
+        self.dynamic_filter = DynamicUpsamplingFilter((5, 5))
+
+        if num_layer == 16:
+            num_block = 3
+            num_grow_ch = 32
+        elif num_layer == 28:
+            num_block = 9
+            num_grow_ch = 16
+        elif num_layer == 52:
+            num_block = 21
+            num_grow_ch = 16
+        else:
+            raise ValueError(f'Only supported (16, 28, 52) layers, but got {num_layer}.')
+
+        self.dense_block1 = DenseBlocks(
+            num_block=num_block, num_feat=64, num_grow_ch=num_grow_ch,
+            adapt_official_weights=adapt_official_weights)  # T = 7
+        self.dense_block2 = DenseBlocksTemporalReduce(
+            64 + num_grow_ch * num_block, num_grow_ch, adapt_official_weights=adapt_official_weights)  # T = 1
+        channels = 64 + num_grow_ch * num_block + num_grow_ch * 3
+        self.bn3d2 = nn.BatchNorm3d(channels, eps=eps, momentum=momentum)
+        self.conv3d2 = nn.Conv3d(channels, 256, (1, 3, 3), stride=(1, 1, 1), padding=(0, 1, 1), bias=True)
+
+        self.conv3d_r1 = nn.Conv3d(256, 256, (1, 1, 1), stride=(1, 1, 1), padding=(0, 0, 0), bias=True)
+        self.conv3d_r2 = nn.Conv3d(256, 3 * (scale**2), (1, 1, 1), stride=(1, 1, 1), padding=(0, 0, 0), bias=True)
+
+        self.conv3d_f1 = nn.Conv3d(256, 512, (1, 1, 1), stride=(1, 1, 1), padding=(0, 0, 0), bias=True)
+        self.conv3d_f2 = nn.Conv3d(
+            512, 1 * 5 * 5 * (scale**2), (1, 1, 1), stride=(1, 1, 1), padding=(0, 0, 0), bias=True)
+
+    def forward(self, x):
+        """
+        Args:
+            x (Tensor): Input with shape (b, 7, c, h, w)
+
+        Returns:
+            Tensor: Output with shape (b, c, h * scale, w * scale)
+        """
+        num_batches, num_imgs, _, h, w = x.size()
+
+        x = x.permute(0, 2, 1, 3, 4)  # (b, c, 7, h, w) for Conv3D
+        x_center = x[:, :, num_imgs // 2, :, :]
+
+        x = self.conv3d1(x)
+        x = self.dense_block1(x)
+        x = self.dense_block2(x)
+        x = F.relu(self.bn3d2(x), inplace=True)
+        x = F.relu(self.conv3d2(x), inplace=True)
+
+        # residual image
+        res = self.conv3d_r2(F.relu(self.conv3d_r1(x), inplace=True))
+
+        # filter
+        filter_ = self.conv3d_f2(F.relu(self.conv3d_f1(x), inplace=True))
+        filter_ = F.softmax(filter_.view(num_batches, 25, self.scale**2, h, w), dim=1)
+
+        # dynamic filter
+        out = self.dynamic_filter(x_center, filter_)
+        out += res.squeeze_(2)
+        out = F.pixel_shuffle(out, self.scale)
+
+        return out

BasicSR/basicsr/archs/ecbsr_arch.py

+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+
+from basicsr.utils.registry import ARCH_REGISTRY
+
+
+class SeqConv3x3(nn.Module):
+    """The re-parameterizable block used in the ECBSR architecture.
+
+    ``Paper: Edge-oriented Convolution Block for Real-time Super Resolution on Mobile Devices``
+
+    Reference: https://github.com/xindongzhang/ECBSR
+
+    Args:
+        seq_type (str): Sequence type, option: conv1x1-conv3x3 | conv1x1-sobelx | conv1x1-sobely | conv1x1-laplacian.
+        in_channels (int): Channel number of input.
+        out_channels (int): Channel number of output.
+        depth_multiplier (int): Width multiplier in the expand-and-squeeze conv. Default: 1.
+    """
+
+    def __init__(self, seq_type, in_channels, out_channels, depth_multiplier=1):
+        super(SeqConv3x3, self).__init__()
+        self.seq_type = seq_type
+        self.in_channels = in_channels
+        self.out_channels = out_channels
+
+        if self.seq_type == 'conv1x1-conv3x3':
+            self.mid_planes = int(out_channels * depth_multiplier)
+            conv0 = torch.nn.Conv2d(self.in_channels, self.mid_planes, kernel_size=1, padding=0)
+            self.k0 = conv0.weight
+            self.b0 = conv0.bias
+
+            conv1 = torch.nn.Conv2d(self.mid_planes, self.out_channels, kernel_size=3)
+            self.k1 = conv1.weight
+            self.b1 = conv1.bias
+
+        elif self.seq_type == 'conv1x1-sobelx':
+            conv0 = torch.nn.Conv2d(self.in_channels, self.out_channels, kernel_size=1, padding=0)
+            self.k0 = conv0.weight
+            self.b0 = conv0.bias
+
+            # init scale and bias
+            scale = torch.randn(size=(self.out_channels, 1, 1, 1)) * 1e-3
+            self.scale = nn.Parameter(scale)
+            bias = torch.randn(self.out_channels) * 1e-3
+            bias = torch.reshape(bias, (self.out_channels, ))
+            self.bias = nn.Parameter(bias)
+            # init mask
+            self.mask = torch.zeros((self.out_channels, 1, 3, 3), dtype=torch.float32)
+            for i in range(self.out_channels):
+                self.mask[i, 0, 0, 0] = 1.0
+                self.mask[i, 0, 1, 0] = 2.0
+                self.mask[i, 0, 2, 0] = 1.0
+                self.mask[i, 0, 0, 2] = -1.0
+                self.mask[i, 0, 1, 2] = -2.0
+                self.mask[i, 0, 2, 2] = -1.0
+            self.mask = nn.Parameter(data=self.mask, requires_grad=False)
+
+        elif self.seq_type == 'conv1x1-sobely':
+            conv0 = torch.nn.Conv2d(self.in_channels, self.out_channels, kernel_size=1, padding=0)
+            self.k0 = conv0.weight
+            self.b0 = conv0.bias
+
+            # init scale and bias
+            scale = torch.randn(size=(self.out_channels, 1, 1, 1)) * 1e-3
+            self.scale = nn.Parameter(torch.FloatTensor(scale))
+            bias = torch.randn(self.out_channels) * 1e-3
+            bias = torch.reshape(bias, (self.out_channels, ))
+            self.bias = nn.Parameter(torch.FloatTensor(bias))
+            # init mask
+            self.mask = torch.zeros((self.out_channels, 1, 3, 3), dtype=torch.float32)
+            for i in range(self.out_channels):
+                self.mask[i, 0, 0, 0] = 1.0
+                self.mask[i, 0, 0, 1] = 2.0
+                self.mask[i, 0, 0, 2] = 1.0
+                self.mask[i, 0, 2, 0] = -1.0
+                self.mask[i, 0, 2, 1] = -2.0
+                self.mask[i, 0, 2, 2] = -1.0
+            self.mask = nn.Parameter(data=self.mask, requires_grad=False)
+
+        elif self.seq_type == 'conv1x1-laplacian':
+            conv0 = torch.nn.Conv2d(self.in_channels, self.out_channels, kernel_size=1, padding=0)
+            self.k0 = conv0.weight
+            self.b0 = conv0.bias
+
+            # init scale and bias
+            scale = torch.randn(size=(self.out_channels, 1, 1, 1)) * 1e-3
+            self.scale = nn.Parameter(torch.FloatTensor(scale))
+            bias = torch.randn(self.out_channels) * 1e-3
+            bias = torch.reshape(bias, (self.out_channels, ))
+            self.bias = nn.Parameter(torch.FloatTensor(bias))
+            # init mask
+            self.mask = torch.zeros((self.out_channels, 1, 3, 3), dtype=torch.float32)
+            for i in range(self.out_channels):
+                self.mask[i, 0, 0, 1] = 1.0
+                self.mask[i, 0, 1, 0] = 1.0
+                self.mask[i, 0, 1, 2] = 1.0
+                self.mask[i, 0, 2, 1] = 1.0
+                self.mask[i, 0, 1, 1] = -4.0
+            self.mask = nn.Parameter(data=self.mask, requires_grad=False)
+        else:
+            raise ValueError('The type of seqconv is not supported!')
+
+    def forward(self, x):
+        if self.seq_type == 'conv1x1-conv3x3':
+            # conv-1x1
+            y0 = F.conv2d(input=x, weight=self.k0, bias=self.b0, stride=1)
+            # explicitly padding with bias
+            y0 = F.pad(y0, (1, 1, 1, 1), 'constant', 0)
+            b0_pad = self.b0.view(1, -1, 1, 1)
+            y0[:, :, 0:1, :] = b0_pad
+            y0[:, :, -1:, :] = b0_pad
+            y0[:, :, :, 0:1] = b0_pad
+            y0[:, :, :, -1:] = b0_pad
+            # conv-3x3
+            y1 = F.conv2d(input=y0, weight=self.k1, bias=self.b1, stride=1)
+        else:
+            y0 = F.conv2d(input=x, weight=self.k0, bias=self.b0, stride=1)
+            # explicitly padding with bias
+            y0 = F.pad(y0, (1, 1, 1, 1), 'constant', 0)
+            b0_pad = self.b0.view(1, -1, 1, 1)
+            y0[:, :, 0:1, :] = b0_pad
+            y0[:, :, -1:, :] = b0_pad
+            y0[:, :, :, 0:1] = b0_pad
+            y0[:, :, :, -1:] = b0_pad
+            # conv-3x3
+            y1 = F.conv2d(input=y0, weight=self.scale * self.mask, bias=self.bias, stride=1, groups=self.out_channels)
+        return y1
+
+    def rep_params(self):
+        device = self.k0.get_device()
+        if device < 0:
+            device = None
+
+        if self.seq_type == 'conv1x1-conv3x3':
+            # re-param conv kernel
+            rep_weight = F.conv2d(input=self.k1, weight=self.k0.permute(1, 0, 2, 3))
+            # re-param conv bias
+            rep_bias = torch.ones(1, self.mid_planes, 3, 3, device=device) * self.b0.view(1, -1, 1, 1)
+            rep_bias = F.conv2d(input=rep_bias, weight=self.k1).view(-1, ) + self.b1
+        else:
+            tmp = self.scale * self.mask
+            k1 = torch.zeros((self.out_channels, self.out_channels, 3, 3), device=device)
+            for i in range(self.out_channels):
+                k1[i, i, :, :] = tmp[i, 0, :, :]
+            b1 = self.bias
+            # re-param conv kernel
+            rep_weight = F.conv2d(input=k1, weight=self.k0.permute(1, 0, 2, 3))
+            # re-param conv bias
+            rep_bias = torch.ones(1, self.out_channels, 3, 3, device=device) * self.b0.view(1, -1, 1, 1)
+            rep_bias = F.conv2d(input=rep_bias, weight=k1).view(-1, ) + b1
+        return rep_weight, rep_bias
+
+
+class ECB(nn.Module):
+    """The ECB block used in the ECBSR architecture.
+
+    Paper: Edge-oriented Convolution Block for Real-time Super Resolution on Mobile Devices
+    Ref git repo: https://github.com/xindongzhang/ECBSR
+
+    Args:
+        in_channels (int): Channel number of input.
+        out_channels (int): Channel number of output.
+        depth_multiplier (int): Width multiplier in the expand-and-squeeze conv. Default: 1.
+        act_type (str): Activation type. Option: prelu | relu | rrelu | softplus | linear. Default: prelu.
+        with_idt (bool): Whether to use identity connection. Default: False.
+    """
+
+    def __init__(self, in_channels, out_channels, depth_multiplier, act_type='prelu', with_idt=False):
+        super(ECB, self).__init__()
+
+        self.depth_multiplier = depth_multiplier
+        self.in_channels = in_channels
+        self.out_channels = out_channels
+        self.act_type = act_type
+
+        if with_idt and (self.in_channels == self.out_channels):
+            self.with_idt = True
+        else:
+            self.with_idt = False
+
+        self.conv3x3 = torch.nn.Conv2d(self.in_channels, self.out_channels, kernel_size=3, padding=1)
+        self.conv1x1_3x3 = SeqConv3x3('conv1x1-conv3x3', self.in_channels, self.out_channels, self.depth_multiplier)
+        self.conv1x1_sbx = SeqConv3x3('conv1x1-sobelx', self.in_channels, self.out_channels)
+        self.conv1x1_sby = SeqConv3x3('conv1x1-sobely', self.in_channels, self.out_channels)
+        self.conv1x1_lpl = SeqConv3x3('conv1x1-laplacian', self.in_channels, self.out_channels)
+
+        if self.act_type == 'prelu':
+            self.act = nn.PReLU(num_parameters=self.out_channels)
+        elif self.act_type == 'relu':
+            self.act = nn.ReLU(inplace=True)
+        elif self.act_type == 'rrelu':
+            self.act = nn.RReLU(lower=-0.05, upper=0.05)
+        elif self.act_type == 'softplus':
+            self.act = nn.Softplus()
+        elif self.act_type == 'linear':
+            pass
+        else:
+            raise ValueError('The type of activation if not support!')
+
+    def forward(self, x):
+        if self.training:
+            y = self.conv3x3(x) + self.conv1x1_3x3(x) + self.conv1x1_sbx(x) + self.conv1x1_sby(x) + self.conv1x1_lpl(x)
+            if self.with_idt:
+                y += x
+        else:
+            rep_weight, rep_bias = self.rep_params()
+            y = F.conv2d(input=x, weight=rep_weight, bias=rep_bias, stride=1, padding=1)
+        if self.act_type != 'linear':
+            y = self.act(y)
+        return y
+
+    def rep_params(self):
+        weight0, bias0 = self.conv3x3.weight, self.conv3x3.bias
+        weight1, bias1 = self.conv1x1_3x3.rep_params()
+        weight2, bias2 = self.conv1x1_sbx.rep_params()
+        weight3, bias3 = self.conv1x1_sby.rep_params()
+        weight4, bias4 = self.conv1x1_lpl.rep_params()
+        rep_weight, rep_bias = (weight0 + weight1 + weight2 + weight3 + weight4), (
+            bias0 + bias1 + bias2 + bias3 + bias4)
+
+        if self.with_idt:
+            device = rep_weight.get_device()
+            if device < 0:
+                device = None
+            weight_idt = torch.zeros(self.out_channels, self.out_channels, 3, 3, device=device)
+            for i in range(self.out_channels):
+                weight_idt[i, i, 1, 1] = 1.0
+            bias_idt = 0.0
+            rep_weight, rep_bias = rep_weight + weight_idt, rep_bias + bias_idt
+        return rep_weight, rep_bias
+
+
+@ARCH_REGISTRY.register()
+class ECBSR(nn.Module):
+    """ECBSR architecture.
+
+    Paper: Edge-oriented Convolution Block for Real-time Super Resolution on Mobile Devices
+    Ref git repo: https://github.com/xindongzhang/ECBSR
+
+    Args:
+        num_in_ch (int): Channel number of inputs.
+        num_out_ch (int): Channel number of outputs.
+        num_block (int): Block number in the trunk network.
+        num_channel (int): Channel number.
+        with_idt (bool): Whether use identity in convolution layers.
+        act_type (str): Activation type.
+        scale (int): Upsampling factor.
+    """
+
+    def __init__(self, num_in_ch, num_out_ch, num_block, num_channel, with_idt, act_type, scale):
+        super(ECBSR, self).__init__()
+        self.num_in_ch = num_in_ch
+        self.scale = scale
+
+        backbone = []
+        backbone += [ECB(num_in_ch, num_channel, depth_multiplier=2.0, act_type=act_type, with_idt=with_idt)]
+        for _ in range(num_block):
+            backbone += [ECB(num_channel, num_channel, depth_multiplier=2.0, act_type=act_type, with_idt=with_idt)]
+        backbone += [
+            ECB(num_channel, num_out_ch * scale * scale, depth_multiplier=2.0, act_type='linear', with_idt=with_idt)
+        ]
+
+        self.backbone = nn.Sequential(*backbone)
+        self.upsampler = nn.PixelShuffle(scale)
+
+    def forward(self, x):
+        if self.num_in_ch > 1:
+            shortcut = torch.repeat_interleave(x, self.scale * self.scale, dim=1)
+        else:
+            shortcut = x  # will repeat the input in the channel dimension (repeat  scale * scale times)
+        y = self.backbone(x) + shortcut
+        y = self.upsampler(y)
+        return y

BasicSR/basicsr/archs/edsr_arch.py

+import torch
+from torch import nn as nn
+
+from basicsr.archs.arch_util import ResidualBlockNoBN, Upsample, make_layer
+from basicsr.utils.registry import ARCH_REGISTRY
+
+
+@ARCH_REGISTRY.register()
+class EDSR(nn.Module):
+    """EDSR network structure.
+
+    Paper: Enhanced Deep Residual Networks for Single Image Super-Resolution.
+    Ref git repo: https://github.com/thstkdgus35/EDSR-PyTorch
+
+    Args:
+        num_in_ch (int): Channel number of inputs.
+        num_out_ch (int): Channel number of outputs.
+        num_feat (int): Channel number of intermediate features.
+            Default: 64.
+        num_block (int): Block number in the trunk network. Default: 16.
+        upscale (int): Upsampling factor. Support 2^n and 3.
+            Default: 4.
+        res_scale (float): Used to scale the residual in residual block.
+            Default: 1.
+        img_range (float): Image range. Default: 255.
+        rgb_mean (tuple[float]): Image mean in RGB orders.
+            Default: (0.4488, 0.4371, 0.4040), calculated from DIV2K dataset.
+    """
+
+    def __init__(self,
+                 num_in_ch,
+                 num_out_ch,
+                 num_feat=64,
+                 num_block=16,
+                 upscale=4,
+                 res_scale=1,
+                 img_range=255.,
+                 rgb_mean=(0.4488, 0.4371, 0.4040)):
+        super(EDSR, self).__init__()
+
+        self.img_range = img_range
+        self.mean = torch.Tensor(rgb_mean).view(1, 3, 1, 1)
+
+        self.conv_first = nn.Conv2d(num_in_ch, num_feat, 3, 1, 1)
+        self.body = make_layer(ResidualBlockNoBN, num_block, num_feat=num_feat, res_scale=res_scale, pytorch_init=True)
+        self.conv_after_body = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+        self.upsample = Upsample(upscale, num_feat)
+        self.conv_last = nn.Conv2d(num_feat, num_out_ch, 3, 1, 1)
+
+    def forward(self, x):
+        self.mean = self.mean.type_as(x)
+
+        x = (x - self.mean) * self.img_range
+        x = self.conv_first(x)
+        res = self.conv_after_body(self.body(x))
+        res += x
+
+        x = self.conv_last(self.upsample(res))
+        x = x / self.img_range + self.mean
+
+        return x

BasicSR/basicsr/archs/edvr_arch.py

+import torch
+from torch import nn as nn
+from torch.nn import functional as F
+
+from basicsr.utils.registry import ARCH_REGISTRY
+from .arch_util import DCNv2Pack, ResidualBlockNoBN, make_layer
+
+
+class PCDAlignment(nn.Module):
+    """Alignment module using Pyramid, Cascading and Deformable convolution
+    (PCD). It is used in EDVR.
+
+    ``Paper: EDVR: Video Restoration with Enhanced Deformable Convolutional Networks``
+
+    Args:
+        num_feat (int): Channel number of middle features. Default: 64.
+        deformable_groups (int): Deformable groups. Defaults: 8.
+    """
+
+    def __init__(self, num_feat=64, deformable_groups=8):
+        super(PCDAlignment, self).__init__()
+
+        # Pyramid has three levels:
+        # L3: level 3, 1/4 spatial size
+        # L2: level 2, 1/2 spatial size
+        # L1: level 1, original spatial size
+        self.offset_conv1 = nn.ModuleDict()
+        self.offset_conv2 = nn.ModuleDict()
+        self.offset_conv3 = nn.ModuleDict()
+        self.dcn_pack = nn.ModuleDict()
+        self.feat_conv = nn.ModuleDict()
+
+        # Pyramids
+        for i in range(3, 0, -1):
+            level = f'l{i}'
+            self.offset_conv1[level] = nn.Conv2d(num_feat * 2, num_feat, 3, 1, 1)
+            if i == 3:
+                self.offset_conv2[level] = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+            else:
+                self.offset_conv2[level] = nn.Conv2d(num_feat * 2, num_feat, 3, 1, 1)
+                self.offset_conv3[level] = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+            self.dcn_pack[level] = DCNv2Pack(num_feat, num_feat, 3, padding=1, deformable_groups=deformable_groups)
+
+            if i < 3:
+                self.feat_conv[level] = nn.Conv2d(num_feat * 2, num_feat, 3, 1, 1)
+
+        # Cascading dcn
+        self.cas_offset_conv1 = nn.Conv2d(num_feat * 2, num_feat, 3, 1, 1)
+        self.cas_offset_conv2 = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+        self.cas_dcnpack = DCNv2Pack(num_feat, num_feat, 3, padding=1, deformable_groups=deformable_groups)
+
+        self.upsample = nn.Upsample(scale_factor=2, mode='bilinear', align_corners=False)
+        self.lrelu = nn.LeakyReLU(negative_slope=0.1, inplace=True)
+
+    def forward(self, nbr_feat_l, ref_feat_l):
+        """Align neighboring frame features to the reference frame features.
+
+        Args:
+            nbr_feat_l (list[Tensor]): Neighboring feature list. It
+                contains three pyramid levels (L1, L2, L3),
+                each with shape (b, c, h, w).
+            ref_feat_l (list[Tensor]): Reference feature list. It
+                contains three pyramid levels (L1, L2, L3),
+                each with shape (b, c, h, w).
+
+        Returns:
+            Tensor: Aligned features.
+        """
+        # Pyramids
+        upsampled_offset, upsampled_feat = None, None
+        for i in range(3, 0, -1):
+            level = f'l{i}'
+            offset = torch.cat([nbr_feat_l[i - 1], ref_feat_l[i - 1]], dim=1)
+            offset = self.lrelu(self.offset_conv1[level](offset))
+            if i == 3:
+                offset = self.lrelu(self.offset_conv2[level](offset))
+            else:
+                offset = self.lrelu(self.offset_conv2[level](torch.cat([offset, upsampled_offset], dim=1)))
+                offset = self.lrelu(self.offset_conv3[level](offset))
+
+            feat = self.dcn_pack[level](nbr_feat_l[i - 1], offset)
+            if i < 3:
+                feat = self.feat_conv[level](torch.cat([feat, upsampled_feat], dim=1))
+            if i > 1:
+                feat = self.lrelu(feat)
+
+            if i > 1:  # upsample offset and features
+                # x2: when we upsample the offset, we should also enlarge
+                # the magnitude.
+                upsampled_offset = self.upsample(offset) * 2
+                upsampled_feat = self.upsample(feat)
+
+        # Cascading
+        offset = torch.cat([feat, ref_feat_l[0]], dim=1)
+        offset = self.lrelu(self.cas_offset_conv2(self.lrelu(self.cas_offset_conv1(offset))))
+        feat = self.lrelu(self.cas_dcnpack(feat, offset))
+        return feat
+
+
+class TSAFusion(nn.Module):
+    """Temporal Spatial Attention (TSA) fusion module.
+
+    Temporal: Calculate the correlation between center frame and
+        neighboring frames;
+    Spatial: It has 3 pyramid levels, the attention is similar to SFT.
+        (SFT: Recovering realistic texture in image super-resolution by deep
+            spatial feature transform.)
+
+    Args:
+        num_feat (int): Channel number of middle features. Default: 64.
+        num_frame (int): Number of frames. Default: 5.
+        center_frame_idx (int): The index of center frame. Default: 2.
+    """
+
+    def __init__(self, num_feat=64, num_frame=5, center_frame_idx=2):
+        super(TSAFusion, self).__init__()
+        self.center_frame_idx = center_frame_idx
+        # temporal attention (before fusion conv)
+        self.temporal_attn1 = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+        self.temporal_attn2 = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+        self.feat_fusion = nn.Conv2d(num_frame * num_feat, num_feat, 1, 1)
+
+        # spatial attention (after fusion conv)
+        self.max_pool = nn.MaxPool2d(3, stride=2, padding=1)
+        self.avg_pool = nn.AvgPool2d(3, stride=2, padding=1)
+        self.spatial_attn1 = nn.Conv2d(num_frame * num_feat, num_feat, 1)
+        self.spatial_attn2 = nn.Conv2d(num_feat * 2, num_feat, 1)
+        self.spatial_attn3 = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+        self.spatial_attn4 = nn.Conv2d(num_feat, num_feat, 1)
+        self.spatial_attn5 = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+        self.spatial_attn_l1 = nn.Conv2d(num_feat, num_feat, 1)
+        self.spatial_attn_l2 = nn.Conv2d(num_feat * 2, num_feat, 3, 1, 1)
+        self.spatial_attn_l3 = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+        self.spatial_attn_add1 = nn.Conv2d(num_feat, num_feat, 1)
+        self.spatial_attn_add2 = nn.Conv2d(num_feat, num_feat, 1)
+
+        self.lrelu = nn.LeakyReLU(negative_slope=0.1, inplace=True)
+        self.upsample = nn.Upsample(scale_factor=2, mode='bilinear', align_corners=False)
+
+    def forward(self, aligned_feat):
+        """
+        Args:
+            aligned_feat (Tensor): Aligned features with shape (b, t, c, h, w).
+
+        Returns:
+            Tensor: Features after TSA with the shape (b, c, h, w).
+        """
+        b, t, c, h, w = aligned_feat.size()
+        # temporal attention
+        embedding_ref = self.temporal_attn1(aligned_feat[:, self.center_frame_idx, :, :, :].clone())
+        embedding = self.temporal_attn2(aligned_feat.view(-1, c, h, w))
+        embedding = embedding.view(b, t, -1, h, w)  # (b, t, c, h, w)
+
+        corr_l = []  # correlation list
+        for i in range(t):
+            emb_neighbor = embedding[:, i, :, :, :]
+            corr = torch.sum(emb_neighbor * embedding_ref, 1)  # (b, h, w)
+            corr_l.append(corr.unsqueeze(1))  # (b, 1, h, w)
+        corr_prob = torch.sigmoid(torch.cat(corr_l, dim=1))  # (b, t, h, w)
+        corr_prob = corr_prob.unsqueeze(2).expand(b, t, c, h, w)
+        corr_prob = corr_prob.contiguous().view(b, -1, h, w)  # (b, t*c, h, w)
+        aligned_feat = aligned_feat.view(b, -1, h, w) * corr_prob
+
+        # fusion
+        feat = self.lrelu(self.feat_fusion(aligned_feat))
+
+        # spatial attention
+        attn = self.lrelu(self.spatial_attn1(aligned_feat))
+        attn_max = self.max_pool(attn)
+        attn_avg = self.avg_pool(attn)
+        attn = self.lrelu(self.spatial_attn2(torch.cat([attn_max, attn_avg], dim=1)))
+        # pyramid levels
+        attn_level = self.lrelu(self.spatial_attn_l1(attn))
+        attn_max = self.max_pool(attn_level)
+        attn_avg = self.avg_pool(attn_level)
+        attn_level = self.lrelu(self.spatial_attn_l2(torch.cat([attn_max, attn_avg], dim=1)))
+        attn_level = self.lrelu(self.spatial_attn_l3(attn_level))
+        attn_level = self.upsample(attn_level)
+
+        attn = self.lrelu(self.spatial_attn3(attn)) + attn_level
+        attn = self.lrelu(self.spatial_attn4(attn))
+        attn = self.upsample(attn)
+        attn = self.spatial_attn5(attn)
+        attn_add = self.spatial_attn_add2(self.lrelu(self.spatial_attn_add1(attn)))
+        attn = torch.sigmoid(attn)
+
+        # after initialization, * 2 makes (attn * 2) to be close to 1.
+        feat = feat * attn * 2 + attn_add
+        return feat
+
+
+class PredeblurModule(nn.Module):
+    """Pre-dublur module.
+
+    Args:
+        num_in_ch (int): Channel number of input image. Default: 3.
+        num_feat (int): Channel number of intermediate features. Default: 64.
+        hr_in (bool): Whether the input has high resolution. Default: False.
+    """
+
+    def __init__(self, num_in_ch=3, num_feat=64, hr_in=False):
+        super(PredeblurModule, self).__init__()
+        self.hr_in = hr_in
+
+        self.conv_first = nn.Conv2d(num_in_ch, num_feat, 3, 1, 1)
+        if self.hr_in:
+            # downsample x4 by stride conv
+            self.stride_conv_hr1 = nn.Conv2d(num_feat, num_feat, 3, 2, 1)
+            self.stride_conv_hr2 = nn.Conv2d(num_feat, num_feat, 3, 2, 1)
+
+        # generate feature pyramid
+        self.stride_conv_l2 = nn.Conv2d(num_feat, num_feat, 3, 2, 1)
+        self.stride_conv_l3 = nn.Conv2d(num_feat, num_feat, 3, 2, 1)
+
+        self.resblock_l3 = ResidualBlockNoBN(num_feat=num_feat)
+        self.resblock_l2_1 = ResidualBlockNoBN(num_feat=num_feat)
+        self.resblock_l2_2 = ResidualBlockNoBN(num_feat=num_feat)
+        self.resblock_l1 = nn.ModuleList([ResidualBlockNoBN(num_feat=num_feat) for i in range(5)])
+
+        self.upsample = nn.Upsample(scale_factor=2, mode='bilinear', align_corners=False)
+        self.lrelu = nn.LeakyReLU(negative_slope=0.1, inplace=True)
+
+    def forward(self, x):
+        feat_l1 = self.lrelu(self.conv_first(x))
+        if self.hr_in:
+            feat_l1 = self.lrelu(self.stride_conv_hr1(feat_l1))
+            feat_l1 = self.lrelu(self.stride_conv_hr2(feat_l1))
+
+        # generate feature pyramid
+        feat_l2 = self.lrelu(self.stride_conv_l2(feat_l1))
+        feat_l3 = self.lrelu(self.stride_conv_l3(feat_l2))
+
+        feat_l3 = self.upsample(self.resblock_l3(feat_l3))
+        feat_l2 = self.resblock_l2_1(feat_l2) + feat_l3
+        feat_l2 = self.upsample(self.resblock_l2_2(feat_l2))
+
+        for i in range(2):
+            feat_l1 = self.resblock_l1[i](feat_l1)
+        feat_l1 = feat_l1 + feat_l2
+        for i in range(2, 5):
+            feat_l1 = self.resblock_l1[i](feat_l1)
+        return feat_l1
+
+
+@ARCH_REGISTRY.register()
+class EDVR(nn.Module):
+    """EDVR network structure for video super-resolution.
+
+    Now only support X4 upsampling factor.
+
+    ``Paper: EDVR: Video Restoration with Enhanced Deformable Convolutional Networks``
+
+    Args:
+        num_in_ch (int): Channel number of input image. Default: 3.
+        num_out_ch (int): Channel number of output image. Default: 3.
+        num_feat (int): Channel number of intermediate features. Default: 64.
+        num_frame (int): Number of input frames. Default: 5.
+        deformable_groups (int): Deformable groups. Defaults: 8.
+        num_extract_block (int): Number of blocks for feature extraction.
+            Default: 5.
+        num_reconstruct_block (int): Number of blocks for reconstruction.
+            Default: 10.
+        center_frame_idx (int): The index of center frame. Frame counting from
+            0. Default: Middle of input frames.
+        hr_in (bool): Whether the input has high resolution. Default: False.
+        with_predeblur (bool): Whether has predeblur module.
+            Default: False.
+        with_tsa (bool): Whether has TSA module. Default: True.
+    """
+
+    def __init__(self,
+                 num_in_ch=3,
+                 num_out_ch=3,
+                 num_feat=64,
+                 num_frame=5,
+                 deformable_groups=8,
+                 num_extract_block=5,
+                 num_reconstruct_block=10,
+                 center_frame_idx=None,
+                 hr_in=False,
+                 with_predeblur=False,
+                 with_tsa=True):
+        super(EDVR, self).__init__()
+        if center_frame_idx is None:
+            self.center_frame_idx = num_frame // 2
+        else:
+            self.center_frame_idx = center_frame_idx
+        self.hr_in = hr_in
+        self.with_predeblur = with_predeblur
+        self.with_tsa = with_tsa
+
+        # extract features for each frame
+        if self.with_predeblur:
+            self.predeblur = PredeblurModule(num_feat=num_feat, hr_in=self.hr_in)
+            self.conv_1x1 = nn.Conv2d(num_feat, num_feat, 1, 1)
+        else:
+            self.conv_first = nn.Conv2d(num_in_ch, num_feat, 3, 1, 1)
+
+        # extract pyramid features
+        self.feature_extraction = make_layer(ResidualBlockNoBN, num_extract_block, num_feat=num_feat)
+        self.conv_l2_1 = nn.Conv2d(num_feat, num_feat, 3, 2, 1)
+        self.conv_l2_2 = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+        self.conv_l3_1 = nn.Conv2d(num_feat, num_feat, 3, 2, 1)
+        self.conv_l3_2 = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+
+        # pcd and tsa module
+        self.pcd_align = PCDAlignment(num_feat=num_feat, deformable_groups=deformable_groups)
+        if self.with_tsa:
+            self.fusion = TSAFusion(num_feat=num_feat, num_frame=num_frame, center_frame_idx=self.center_frame_idx)
+        else:
+            self.fusion = nn.Conv2d(num_frame * num_feat, num_feat, 1, 1)
+
+        # reconstruction
+        self.reconstruction = make_layer(ResidualBlockNoBN, num_reconstruct_block, num_feat=num_feat)
+        # upsample
+        self.upconv1 = nn.Conv2d(num_feat, num_feat * 4, 3, 1, 1)
+        self.upconv2 = nn.Conv2d(num_feat, 64 * 4, 3, 1, 1)
+        self.pixel_shuffle = nn.PixelShuffle(2)
+        self.conv_hr = nn.Conv2d(64, 64, 3, 1, 1)
+        self.conv_last = nn.Conv2d(64, 3, 3, 1, 1)
+
+        # activation function
+        self.lrelu = nn.LeakyReLU(negative_slope=0.1, inplace=True)
+
+    def forward(self, x):
+        b, t, c, h, w = x.size()
+        if self.hr_in:
+            assert h % 16 == 0 and w % 16 == 0, ('The height and width must be multiple of 16.')
+        else:
+            assert h % 4 == 0 and w % 4 == 0, ('The height and width must be multiple of 4.')
+
+        x_center = x[:, self.center_frame_idx, :, :, :].contiguous()
+
+        # extract features for each frame
+        # L1
+        if self.with_predeblur:
+            feat_l1 = self.conv_1x1(self.predeblur(x.view(-1, c, h, w)))
+            if self.hr_in:
+                h, w = h // 4, w // 4
+        else:
+            feat_l1 = self.lrelu(self.conv_first(x.view(-1, c, h, w)))
+
+        feat_l1 = self.feature_extraction(feat_l1)
+        # L2
+        feat_l2 = self.lrelu(self.conv_l2_1(feat_l1))
+        feat_l2 = self.lrelu(self.conv_l2_2(feat_l2))
+        # L3
+        feat_l3 = self.lrelu(self.conv_l3_1(feat_l2))
+        feat_l3 = self.lrelu(self.conv_l3_2(feat_l3))
+
+        feat_l1 = feat_l1.view(b, t, -1, h, w)
+        feat_l2 = feat_l2.view(b, t, -1, h // 2, w // 2)
+        feat_l3 = feat_l3.view(b, t, -1, h // 4, w // 4)
+
+        # PCD alignment
+        ref_feat_l = [  # reference feature list
+            feat_l1[:, self.center_frame_idx, :, :, :].clone(), feat_l2[:, self.center_frame_idx, :, :, :].clone(),
+            feat_l3[:, self.center_frame_idx, :, :, :].clone()
+        ]
+        aligned_feat = []
+        for i in range(t):
+            nbr_feat_l = [  # neighboring feature list
+                feat_l1[:, i, :, :, :].clone(), feat_l2[:, i, :, :, :].clone(), feat_l3[:, i, :, :, :].clone()
+            ]
+            aligned_feat.append(self.pcd_align(nbr_feat_l, ref_feat_l))
+        aligned_feat = torch.stack(aligned_feat, dim=1)  # (b, t, c, h, w)
+
+        if not self.with_tsa:
+            aligned_feat = aligned_feat.view(b, -1, h, w)
+        feat = self.fusion(aligned_feat)
+
+        out = self.reconstruction(feat)
+        out = self.lrelu(self.pixel_shuffle(self.upconv1(out)))
+        out = self.lrelu(self.pixel_shuffle(self.upconv2(out)))
+        out = self.lrelu(self.conv_hr(out))
+        out = self.conv_last(out)
+        if self.hr_in:
+            base = x_center
+        else:
+            base = F.interpolate(x_center, scale_factor=4, mode='bilinear', align_corners=False)
+        out += base
+        return out

BasicSR/basicsr/archs/hifacegan_arch.py

+import numpy as np
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+
+from basicsr.utils.registry import ARCH_REGISTRY
+from .hifacegan_util import BaseNetwork, LIPEncoder, SPADEResnetBlock, get_nonspade_norm_layer
+
+
+class SPADEGenerator(BaseNetwork):
+    """Generator with SPADEResBlock"""
+
+    def __init__(self,
+                 num_in_ch=3,
+                 num_feat=64,
+                 use_vae=False,
+                 z_dim=256,
+                 crop_size=512,
+                 norm_g='spectralspadesyncbatch3x3',
+                 is_train=True,
+                 init_train_phase=3):  # progressive training disabled
+        super().__init__()
+        self.nf = num_feat
+        self.input_nc = num_in_ch
+        self.is_train = is_train
+        self.train_phase = init_train_phase
+
+        self.scale_ratio = 5  # hardcoded now
+        self.sw = crop_size // (2**self.scale_ratio)
+        self.sh = self.sw  # 20210519: By default use square image, aspect_ratio = 1.0
+
+        if use_vae:
+            # In case of VAE, we will sample from random z vector
+            self.fc = nn.Linear(z_dim, 16 * self.nf * self.sw * self.sh)
+        else:
+            # Otherwise, we make the network deterministic by starting with
+            # downsampled segmentation map instead of random z
+            self.fc = nn.Conv2d(num_in_ch, 16 * self.nf, 3, padding=1)
+
+        self.head_0 = SPADEResnetBlock(16 * self.nf, 16 * self.nf, norm_g)
+
+        self.g_middle_0 = SPADEResnetBlock(16 * self.nf, 16 * self.nf, norm_g)
+        self.g_middle_1 = SPADEResnetBlock(16 * self.nf, 16 * self.nf, norm_g)
+
+        self.ups = nn.ModuleList([
+            SPADEResnetBlock(16 * self.nf, 8 * self.nf, norm_g),
+            SPADEResnetBlock(8 * self.nf, 4 * self.nf, norm_g),
+            SPADEResnetBlock(4 * self.nf, 2 * self.nf, norm_g),
+            SPADEResnetBlock(2 * self.nf, 1 * self.nf, norm_g)
+        ])
+
+        self.to_rgbs = nn.ModuleList([
+            nn.Conv2d(8 * self.nf, 3, 3, padding=1),
+            nn.Conv2d(4 * self.nf, 3, 3, padding=1),
+            nn.Conv2d(2 * self.nf, 3, 3, padding=1),
+            nn.Conv2d(1 * self.nf, 3, 3, padding=1)
+        ])
+
+        self.up = nn.Upsample(scale_factor=2)
+
+    def encode(self, input_tensor):
+        """
+        Encode input_tensor into feature maps, can be overridden in derived classes
+        Default: nearest downsampling of 2**5 = 32 times
+        """
+        h, w = input_tensor.size()[-2:]
+        sh, sw = h // 2**self.scale_ratio, w // 2**self.scale_ratio
+        x = F.interpolate(input_tensor, size=(sh, sw))
+        return self.fc(x)
+
+    def forward(self, x):
+        # In oroginal SPADE, seg means a segmentation map, but here we use x instead.
+        seg = x
+
+        x = self.encode(x)
+        x = self.head_0(x, seg)
+
+        x = self.up(x)
+        x = self.g_middle_0(x, seg)
+        x = self.g_middle_1(x, seg)
+
+        if self.is_train:
+            phase = self.train_phase + 1
+        else:
+            phase = len(self.to_rgbs)
+
+        for i in range(phase):
+            x = self.up(x)
+            x = self.ups[i](x, seg)
+
+        x = self.to_rgbs[phase - 1](F.leaky_relu(x, 2e-1))
+        x = torch.tanh(x)
+
+        return x
+
+    def mixed_guidance_forward(self, input_x, seg=None, n=0, mode='progressive'):
+        """
+        A helper class for subspace visualization. Input and seg are different images.
+        For the first n levels (including encoder) we use input, for the rest we use seg.
+
+        If mode = 'progressive', the output's like: AAABBB
+        If mode = 'one_plug', the output's like:    AAABAA
+        If mode = 'one_ablate', the output's like:  BBBABB
+        """
+
+        if seg is None:
+            return self.forward(input_x)
+
+        if self.is_train:
+            phase = self.train_phase + 1
+        else:
+            phase = len(self.to_rgbs)
+
+        if mode == 'progressive':
+            n = max(min(n, 4 + phase), 0)
+            guide_list = [input_x] * n + [seg] * (4 + phase - n)
+        elif mode == 'one_plug':
+            n = max(min(n, 4 + phase - 1), 0)
+            guide_list = [seg] * (4 + phase)
+            guide_list[n] = input_x
+        elif mode == 'one_ablate':
+            if n > 3 + phase:
+                return self.forward(input_x)
+            guide_list = [input_x] * (4 + phase)
+            guide_list[n] = seg
+
+        x = self.encode(guide_list[0])
+        x = self.head_0(x, guide_list[1])
+
+        x = self.up(x)
+        x = self.g_middle_0(x, guide_list[2])
+        x = self.g_middle_1(x, guide_list[3])
+
+        for i in range(phase):
+            x = self.up(x)
+            x = self.ups[i](x, guide_list[4 + i])
+
+        x = self.to_rgbs[phase - 1](F.leaky_relu(x, 2e-1))
+        x = torch.tanh(x)
+
+        return x
+
+
+@ARCH_REGISTRY.register()
+class HiFaceGAN(SPADEGenerator):
+    """
+    HiFaceGAN: SPADEGenerator with a learnable feature encoder
+    Current encoder design: LIPEncoder
+    """
+
+    def __init__(self,
+                 num_in_ch=3,
+                 num_feat=64,
+                 use_vae=False,
+                 z_dim=256,
+                 crop_size=512,
+                 norm_g='spectralspadesyncbatch3x3',
+                 is_train=True,
+                 init_train_phase=3):
+        super().__init__(num_in_ch, num_feat, use_vae, z_dim, crop_size, norm_g, is_train, init_train_phase)
+        self.lip_encoder = LIPEncoder(num_in_ch, num_feat, self.sw, self.sh, self.scale_ratio)
+
+    def encode(self, input_tensor):
+        return self.lip_encoder(input_tensor)
+
+
+@ARCH_REGISTRY.register()
+class HiFaceGANDiscriminator(BaseNetwork):
+    """
+    Inspired by pix2pixHD multiscale discriminator.
+
+    Args:
+        num_in_ch (int): Channel number of inputs. Default: 3.
+        num_out_ch (int): Channel number of outputs. Default: 3.
+        conditional_d (bool): Whether use conditional discriminator.
+            Default: True.
+        num_d (int): Number of Multiscale discriminators. Default: 3.
+        n_layers_d (int): Number of downsample layers in each D. Default: 4.
+        num_feat (int): Channel number of base intermediate features.
+            Default: 64.
+        norm_d (str): String to determine normalization layers in D.
+            Choices: [spectral][instance/batch/syncbatch]
+            Default: 'spectralinstance'.
+        keep_features (bool): Keep intermediate features for matching loss, etc.
+            Default: True.
+    """
+
+    def __init__(self,
+                 num_in_ch=3,
+                 num_out_ch=3,
+                 conditional_d=True,
+                 num_d=2,
+                 n_layers_d=4,
+                 num_feat=64,
+                 norm_d='spectralinstance',
+                 keep_features=True):
+        super().__init__()
+        self.num_d = num_d
+
+        input_nc = num_in_ch
+        if conditional_d:
+            input_nc += num_out_ch
+
+        for i in range(num_d):
+            subnet_d = NLayerDiscriminator(input_nc, n_layers_d, num_feat, norm_d, keep_features)
+            self.add_module(f'discriminator_{i}', subnet_d)
+
+    def downsample(self, x):
+        return F.avg_pool2d(x, kernel_size=3, stride=2, padding=[1, 1], count_include_pad=False)
+
+    # Returns list of lists of discriminator outputs.
+    # The final result is of size opt.num_d x opt.n_layers_D
+    def forward(self, x):
+        result = []
+        for _, _net_d in self.named_children():
+            out = _net_d(x)
+            result.append(out)
+            x = self.downsample(x)
+
+        return result
+
+
+class NLayerDiscriminator(BaseNetwork):
+    """Defines the PatchGAN discriminator with the specified arguments."""
+
+    def __init__(self, input_nc, n_layers_d, num_feat, norm_d, keep_features):
+        super().__init__()
+        kw = 4
+        padw = int(np.ceil((kw - 1.0) / 2))
+        nf = num_feat
+        self.keep_features = keep_features
+
+        norm_layer = get_nonspade_norm_layer(norm_d)
+        sequence = [[nn.Conv2d(input_nc, nf, kernel_size=kw, stride=2, padding=padw), nn.LeakyReLU(0.2, False)]]
+
+        for n in range(1, n_layers_d):
+            nf_prev = nf
+            nf = min(nf * 2, 512)
+            stride = 1 if n == n_layers_d - 1 else 2
+            sequence += [[
+                norm_layer(nn.Conv2d(nf_prev, nf, kernel_size=kw, stride=stride, padding=padw)),
+                nn.LeakyReLU(0.2, False)
+            ]]
+
+        sequence += [[nn.Conv2d(nf, 1, kernel_size=kw, stride=1, padding=padw)]]
+
+        # We divide the layers into groups to extract intermediate layer outputs
+        for n in range(len(sequence)):
+            self.add_module('model' + str(n), nn.Sequential(*sequence[n]))
+
+    def forward(self, x):
+        results = [x]
+        for submodel in self.children():
+            intermediate_output = submodel(results[-1])
+            results.append(intermediate_output)
+
+        if self.keep_features:
+            return results[1:]
+        else:
+            return results[-1]

BasicSR/basicsr/archs/hifacegan_util.py

+import re
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+from torch.nn import init
+# Warning: spectral norm could be buggy
+# under eval mode and multi-GPU inference
+# A workaround is sticking to single-GPU inference and train mode
+from torch.nn.utils import spectral_norm
+
+
+class SPADE(nn.Module):
+
+    def __init__(self, config_text, norm_nc, label_nc):
+        super().__init__()
+
+        assert config_text.startswith('spade')
+        parsed = re.search('spade(\\D+)(\\d)x\\d', config_text)
+        param_free_norm_type = str(parsed.group(1))
+        ks = int(parsed.group(2))
+
+        if param_free_norm_type == 'instance':
+            self.param_free_norm = nn.InstanceNorm2d(norm_nc)
+        elif param_free_norm_type == 'syncbatch':
+            print('SyncBatchNorm is currently not supported under single-GPU mode, switch to "instance" instead')
+            self.param_free_norm = nn.InstanceNorm2d(norm_nc)
+        elif param_free_norm_type == 'batch':
+            self.param_free_norm = nn.BatchNorm2d(norm_nc, affine=False)
+        else:
+            raise ValueError(f'{param_free_norm_type} is not a recognized param-free norm type in SPADE')
+
+        # The dimension of the intermediate embedding space. Yes, hardcoded.
+        nhidden = 128 if norm_nc > 128 else norm_nc
+
+        pw = ks // 2
+        self.mlp_shared = nn.Sequential(nn.Conv2d(label_nc, nhidden, kernel_size=ks, padding=pw), nn.ReLU())
+        self.mlp_gamma = nn.Conv2d(nhidden, norm_nc, kernel_size=ks, padding=pw, bias=False)
+        self.mlp_beta = nn.Conv2d(nhidden, norm_nc, kernel_size=ks, padding=pw, bias=False)
+
+    def forward(self, x, segmap):
+
+        # Part 1. generate parameter-free normalized activations
+        normalized = self.param_free_norm(x)
+
+        # Part 2. produce scaling and bias conditioned on semantic map
+        segmap = F.interpolate(segmap, size=x.size()[2:], mode='nearest')
+        actv = self.mlp_shared(segmap)
+        gamma = self.mlp_gamma(actv)
+        beta = self.mlp_beta(actv)
+
+        # apply scale and bias
+        out = normalized * gamma + beta
+
+        return out
+
+
+class SPADEResnetBlock(nn.Module):
+    """
+    ResNet block that uses SPADE. It differs from the ResNet block of pix2pixHD in that
+    it takes in the segmentation map as input, learns the skip connection if necessary,
+    and applies normalization first and then convolution.
+    This architecture seemed like a standard architecture for unconditional or
+    class-conditional GAN architecture using residual block.
+    The code was inspired from https://github.com/LMescheder/GAN_stability.
+    """
+
+    def __init__(self, fin, fout, norm_g='spectralspadesyncbatch3x3', semantic_nc=3):
+        super().__init__()
+        # Attributes
+        self.learned_shortcut = (fin != fout)
+        fmiddle = min(fin, fout)
+
+        # create conv layers
+        self.conv_0 = nn.Conv2d(fin, fmiddle, kernel_size=3, padding=1)
+        self.conv_1 = nn.Conv2d(fmiddle, fout, kernel_size=3, padding=1)
+        if self.learned_shortcut:
+            self.conv_s = nn.Conv2d(fin, fout, kernel_size=1, bias=False)
+
+        # apply spectral norm if specified
+        if 'spectral' in norm_g:
+            self.conv_0 = spectral_norm(self.conv_0)
+            self.conv_1 = spectral_norm(self.conv_1)
+            if self.learned_shortcut:
+                self.conv_s = spectral_norm(self.conv_s)
+
+        # define normalization layers
+        spade_config_str = norm_g.replace('spectral', '')
+        self.norm_0 = SPADE(spade_config_str, fin, semantic_nc)
+        self.norm_1 = SPADE(spade_config_str, fmiddle, semantic_nc)
+        if self.learned_shortcut:
+            self.norm_s = SPADE(spade_config_str, fin, semantic_nc)
+
+    # note the resnet block with SPADE also takes in |seg|,
+    # the semantic segmentation map as input
+    def forward(self, x, seg):
+        x_s = self.shortcut(x, seg)
+        dx = self.conv_0(self.act(self.norm_0(x, seg)))
+        dx = self.conv_1(self.act(self.norm_1(dx, seg)))
+        out = x_s + dx
+        return out
+
+    def shortcut(self, x, seg):
+        if self.learned_shortcut:
+            x_s = self.conv_s(self.norm_s(x, seg))
+        else:
+            x_s = x
+        return x_s
+
+    def act(self, x):
+        return F.leaky_relu(x, 2e-1)
+
+
+class BaseNetwork(nn.Module):
+    """ A basis for hifacegan archs with custom initialization """
+
+    def init_weights(self, init_type='normal', gain=0.02):
+
+        def init_func(m):
+            classname = m.__class__.__name__
+            if classname.find('BatchNorm2d') != -1:
+                if hasattr(m, 'weight') and m.weight is not None:
+                    init.normal_(m.weight.data, 1.0, gain)
+                if hasattr(m, 'bias') and m.bias is not None:
+                    init.constant_(m.bias.data, 0.0)
+            elif hasattr(m, 'weight') and (classname.find('Conv') != -1 or classname.find('Linear') != -1):
+                if init_type == 'normal':
+                    init.normal_(m.weight.data, 0.0, gain)
+                elif init_type == 'xavier':
+                    init.xavier_normal_(m.weight.data, gain=gain)
+                elif init_type == 'xavier_uniform':
+                    init.xavier_uniform_(m.weight.data, gain=1.0)
+                elif init_type == 'kaiming':
+                    init.kaiming_normal_(m.weight.data, a=0, mode='fan_in')
+                elif init_type == 'orthogonal':
+                    init.orthogonal_(m.weight.data, gain=gain)
+                elif init_type == 'none':  # uses pytorch's default init method
+                    m.reset_parameters()
+                else:
+                    raise NotImplementedError(f'initialization method [{init_type}] is not implemented')
+                if hasattr(m, 'bias') and m.bias is not None:
+                    init.constant_(m.bias.data, 0.0)
+
+        self.apply(init_func)
+
+        # propagate to children
+        for m in self.children():
+            if hasattr(m, 'init_weights'):
+                m.init_weights(init_type, gain)
+
+    def forward(self, x):
+        pass
+
+
+def lip2d(x, logit, kernel=3, stride=2, padding=1):
+    weight = logit.exp()
+    return F.avg_pool2d(x * weight, kernel, stride, padding) / F.avg_pool2d(weight, kernel, stride, padding)
+
+
+class SoftGate(nn.Module):
+    COEFF = 12.0
+
+    def forward(self, x):
+        return torch.sigmoid(x).mul(self.COEFF)
+
+
+class SimplifiedLIP(nn.Module):
+
+    def __init__(self, channels):
+        super(SimplifiedLIP, self).__init__()
+        self.logit = nn.Sequential(
+            nn.Conv2d(channels, channels, 3, padding=1, bias=False), nn.InstanceNorm2d(channels, affine=True),
+            SoftGate())
+
+    def init_layer(self):
+        self.logit[0].weight.data.fill_(0.0)
+
+    def forward(self, x):
+        frac = lip2d(x, self.logit(x))
+        return frac
+
+
+class LIPEncoder(BaseNetwork):
+    """Local Importance-based Pooling (Ziteng Gao et.al.,ICCV 2019)"""
+
+    def __init__(self, input_nc, ngf, sw, sh, n_2xdown, norm_layer=nn.InstanceNorm2d):
+        super().__init__()
+        self.sw = sw
+        self.sh = sh
+        self.max_ratio = 16
+        # 20200310: Several Convolution (stride 1) + LIP blocks, 4 fold
+        kw = 3
+        pw = (kw - 1) // 2
+
+        model = [
+            nn.Conv2d(input_nc, ngf, kw, stride=1, padding=pw, bias=False),
+            norm_layer(ngf),
+            nn.ReLU(),
+        ]
+        cur_ratio = 1
+        for i in range(n_2xdown):
+            next_ratio = min(cur_ratio * 2, self.max_ratio)
+            model += [
+                SimplifiedLIP(ngf * cur_ratio),
+                nn.Conv2d(ngf * cur_ratio, ngf * next_ratio, kw, stride=1, padding=pw),
+                norm_layer(ngf * next_ratio),
+            ]
+            cur_ratio = next_ratio
+            if i < n_2xdown - 1:
+                model += [nn.ReLU(inplace=True)]
+
+        self.model = nn.Sequential(*model)
+
+    def forward(self, x):
+        return self.model(x)
+
+
+def get_nonspade_norm_layer(norm_type='instance'):
+    # helper function to get # output channels of the previous layer
+    def get_out_channel(layer):
+        if hasattr(layer, 'out_channels'):
+            return getattr(layer, 'out_channels')
+        return layer.weight.size(0)
+
+    # this function will be returned
+    def add_norm_layer(layer):
+        nonlocal norm_type
+        if norm_type.startswith('spectral'):
+            layer = spectral_norm(layer)
+            subnorm_type = norm_type[len('spectral'):]
+
+        if subnorm_type == 'none' or len(subnorm_type) == 0:
+            return layer
+
+        # remove bias in the previous layer, which is meaningless
+        # since it has no effect after normalization
+        if getattr(layer, 'bias', None) is not None:
+            delattr(layer, 'bias')
+            layer.register_parameter('bias', None)
+
+        if subnorm_type == 'batch':
+            norm_layer = nn.BatchNorm2d(get_out_channel(layer), affine=True)
+        elif subnorm_type == 'sync_batch':
+            print('SyncBatchNorm is currently not supported under single-GPU mode, switch to "instance" instead')
+            # norm_layer = SynchronizedBatchNorm2d(
+            #    get_out_channel(layer), affine=True)
+            norm_layer = nn.InstanceNorm2d(get_out_channel(layer), affine=False)
+        elif subnorm_type == 'instance':
+            norm_layer = nn.InstanceNorm2d(get_out_channel(layer), affine=False)
+        else:
+            raise ValueError(f'normalization layer {subnorm_type} is not recognized')
+
+        return nn.Sequential(layer, norm_layer)
+
+    print('This is a legacy from nvlabs/SPADE, and will be removed in future versions.')
+    return add_norm_layer

BasicSR/basicsr/archs/inception.py

+# Modified from https://github.com/mseitzer/pytorch-fid/blob/master/pytorch_fid/inception.py # noqa: E501
+# For FID metric
+
+import os
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+from torch.utils.model_zoo import load_url
+from torchvision import models
+
+# Inception weights ported to Pytorch from
+# http://download.tensorflow.org/models/image/imagenet/inception-2015-12-05.tgz
+FID_WEIGHTS_URL = 'https://github.com/mseitzer/pytorch-fid/releases/download/fid_weights/pt_inception-2015-12-05-6726825d.pth'  # noqa: E501
+LOCAL_FID_WEIGHTS = 'experiments/pretrained_models/pt_inception-2015-12-05-6726825d.pth'  # noqa: E501
+
+
+class InceptionV3(nn.Module):
+    """Pretrained InceptionV3 network returning feature maps"""
+
+    # Index of default block of inception to return,
+    # corresponds to output of final average pooling
+    DEFAULT_BLOCK_INDEX = 3
+
+    # Maps feature dimensionality to their output blocks indices
+    BLOCK_INDEX_BY_DIM = {
+        64: 0,  # First max pooling features
+        192: 1,  # Second max pooling features
+        768: 2,  # Pre-aux classifier features
+        2048: 3  # Final average pooling features
+    }
+
+    def __init__(self,
+                 output_blocks=(DEFAULT_BLOCK_INDEX),
+                 resize_input=True,
+                 normalize_input=True,
+                 requires_grad=False,
+                 use_fid_inception=True):
+        """Build pretrained InceptionV3.
+
+        Args:
+            output_blocks (list[int]): Indices of blocks to return features of.
+                Possible values are:
+                - 0: corresponds to output of first max pooling
+                - 1: corresponds to output of second max pooling
+                - 2: corresponds to output which is fed to aux classifier
+                - 3: corresponds to output of final average pooling
+            resize_input (bool): If true, bilinearly resizes input to width and
+                height 299 before feeding input to model. As the network
+                without fully connected layers is fully convolutional, it
+                should be able to handle inputs of arbitrary size, so resizing
+                might not be strictly needed. Default: True.
+            normalize_input (bool): If true, scales the input from range (0, 1)
+                to the range the pretrained Inception network expects,
+                namely (-1, 1). Default: True.
+            requires_grad (bool): If true, parameters of the model require
+                gradients. Possibly useful for finetuning the network.
+                Default: False.
+            use_fid_inception (bool): If true, uses the pretrained Inception
+                model used in Tensorflow's FID implementation.
+                If false, uses the pretrained Inception model available in
+                torchvision. The FID Inception model has different weights
+                and a slightly different structure from torchvision's
+                Inception model. If you want to compute FID scores, you are
+                strongly advised to set this parameter to true to get
+                comparable results. Default: True.
+        """
+        super(InceptionV3, self).__init__()
+
+        self.resize_input = resize_input
+        self.normalize_input = normalize_input
+        self.output_blocks = sorted(output_blocks)
+        self.last_needed_block = max(output_blocks)
+
+        assert self.last_needed_block <= 3, ('Last possible output block index is 3')
+
+        self.blocks = nn.ModuleList()
+
+        if use_fid_inception:
+            inception = fid_inception_v3()
+        else:
+            try:
+                inception = models.inception_v3(pretrained=True, init_weights=False)
+            except TypeError:
+                # pytorch < 1.5 does not have init_weights for inception_v3
+                inception = models.inception_v3(pretrained=True)
+
+        # Block 0: input to maxpool1
+        block0 = [
+            inception.Conv2d_1a_3x3, inception.Conv2d_2a_3x3, inception.Conv2d_2b_3x3,
+            nn.MaxPool2d(kernel_size=3, stride=2)
+        ]
+        self.blocks.append(nn.Sequential(*block0))
+
+        # Block 1: maxpool1 to maxpool2
+        if self.last_needed_block >= 1:
+            block1 = [inception.Conv2d_3b_1x1, inception.Conv2d_4a_3x3, nn.MaxPool2d(kernel_size=3, stride=2)]
+            self.blocks.append(nn.Sequential(*block1))
+
+        # Block 2: maxpool2 to aux classifier
+        if self.last_needed_block >= 2:
+            block2 = [
+                inception.Mixed_5b,
+                inception.Mixed_5c,
+                inception.Mixed_5d,
+                inception.Mixed_6a,
+                inception.Mixed_6b,
+                inception.Mixed_6c,
+                inception.Mixed_6d,
+                inception.Mixed_6e,
+            ]
+            self.blocks.append(nn.Sequential(*block2))
+
+        # Block 3: aux classifier to final avgpool
+        if self.last_needed_block >= 3:
+            block3 = [
+                inception.Mixed_7a, inception.Mixed_7b, inception.Mixed_7c,
+                nn.AdaptiveAvgPool2d(output_size=(1, 1))
+            ]
+            self.blocks.append(nn.Sequential(*block3))
+
+        for param in self.parameters():
+            param.requires_grad = requires_grad
+
+    def forward(self, x):
+        """Get Inception feature maps.
+
+        Args:
+            x (Tensor): Input tensor of shape (b, 3, h, w).
+                Values are expected to be in range (-1, 1). You can also input
+                (0, 1) with setting normalize_input = True.
+
+        Returns:
+            list[Tensor]: Corresponding to the selected output block, sorted
+            ascending by index.
+        """
+        output = []
+
+        if self.resize_input:
+            x = F.interpolate(x, size=(299, 299), mode='bilinear', align_corners=False)
+
+        if self.normalize_input:
+            x = 2 * x - 1  # Scale from range (0, 1) to range (-1, 1)
+
+        for idx, block in enumerate(self.blocks):
+            x = block(x)
+            if idx in self.output_blocks:
+                output.append(x)
+
+            if idx == self.last_needed_block:
+                break
+
+        return output
+
+
+def fid_inception_v3():
+    """Build pretrained Inception model for FID computation.
+
+    The Inception model for FID computation uses a different set of weights
+    and has a slightly different structure than torchvision's Inception.
+
+    This method first constructs torchvision's Inception and then patches the
+    necessary parts that are different in the FID Inception model.
+    """
+    try:
+        inception = models.inception_v3(num_classes=1008, aux_logits=False, pretrained=False, init_weights=False)
+    except TypeError:
+        # pytorch < 1.5 does not have init_weights for inception_v3
+        inception = models.inception_v3(num_classes=1008, aux_logits=False, pretrained=False)
+
+    inception.Mixed_5b = FIDInceptionA(192, pool_features=32)
+    inception.Mixed_5c = FIDInceptionA(256, pool_features=64)
+    inception.Mixed_5d = FIDInceptionA(288, pool_features=64)
+    inception.Mixed_6b = FIDInceptionC(768, channels_7x7=128)
+    inception.Mixed_6c = FIDInceptionC(768, channels_7x7=160)
+    inception.Mixed_6d = FIDInceptionC(768, channels_7x7=160)
+    inception.Mixed_6e = FIDInceptionC(768, channels_7x7=192)
+    inception.Mixed_7b = FIDInceptionE_1(1280)
+    inception.Mixed_7c = FIDInceptionE_2(2048)
+
+    if os.path.exists(LOCAL_FID_WEIGHTS):
+        state_dict = torch.load(LOCAL_FID_WEIGHTS, map_location=lambda storage, loc: storage)
+    else:
+        state_dict = load_url(FID_WEIGHTS_URL, progress=True)
+
+    inception.load_state_dict(state_dict)
+    return inception
+
+
+class FIDInceptionA(models.inception.InceptionA):
+    """InceptionA block patched for FID computation"""
+
+    def __init__(self, in_channels, pool_features):
+        super(FIDInceptionA, self).__init__(in_channels, pool_features)
+
+    def forward(self, x):
+        branch1x1 = self.branch1x1(x)
+
+        branch5x5 = self.branch5x5_1(x)
+        branch5x5 = self.branch5x5_2(branch5x5)
+
+        branch3x3dbl = self.branch3x3dbl_1(x)
+        branch3x3dbl = self.branch3x3dbl_2(branch3x3dbl)
+        branch3x3dbl = self.branch3x3dbl_3(branch3x3dbl)
+
+        # Patch: Tensorflow's average pool does not use the padded zero's in
+        # its average calculation
+        branch_pool = F.avg_pool2d(x, kernel_size=3, stride=1, padding=1, count_include_pad=False)
+        branch_pool = self.branch_pool(branch_pool)
+
+        outputs = [branch1x1, branch5x5, branch3x3dbl, branch_pool]
+        return torch.cat(outputs, 1)
+
+
+class FIDInceptionC(models.inception.InceptionC):
+    """InceptionC block patched for FID computation"""
+
+    def __init__(self, in_channels, channels_7x7):
+        super(FIDInceptionC, self).__init__(in_channels, channels_7x7)
+
+    def forward(self, x):
+        branch1x1 = self.branch1x1(x)
+
+        branch7x7 = self.branch7x7_1(x)
+        branch7x7 = self.branch7x7_2(branch7x7)
+        branch7x7 = self.branch7x7_3(branch7x7)
+
+        branch7x7dbl = self.branch7x7dbl_1(x)
+        branch7x7dbl = self.branch7x7dbl_2(branch7x7dbl)
+        branch7x7dbl = self.branch7x7dbl_3(branch7x7dbl)
+        branch7x7dbl = self.branch7x7dbl_4(branch7x7dbl)
+        branch7x7dbl = self.branch7x7dbl_5(branch7x7dbl)
+
+        # Patch: Tensorflow's average pool does not use the padded zero's in
+        # its average calculation
+        branch_pool = F.avg_pool2d(x, kernel_size=3, stride=1, padding=1, count_include_pad=False)
+        branch_pool = self.branch_pool(branch_pool)
+
+        outputs = [branch1x1, branch7x7, branch7x7dbl, branch_pool]
+        return torch.cat(outputs, 1)
+
+
+class FIDInceptionE_1(models.inception.InceptionE):
+    """First InceptionE block patched for FID computation"""
+
+    def __init__(self, in_channels):
+        super(FIDInceptionE_1, self).__init__(in_channels)
+
+    def forward(self, x):
+        branch1x1 = self.branch1x1(x)
+
+        branch3x3 = self.branch3x3_1(x)
+        branch3x3 = [
+            self.branch3x3_2a(branch3x3),
+            self.branch3x3_2b(branch3x3),
+        ]
+        branch3x3 = torch.cat(branch3x3, 1)
+
+        branch3x3dbl = self.branch3x3dbl_1(x)
+        branch3x3dbl = self.branch3x3dbl_2(branch3x3dbl)
+        branch3x3dbl = [
+            self.branch3x3dbl_3a(branch3x3dbl),
+            self.branch3x3dbl_3b(branch3x3dbl),
+        ]
+        branch3x3dbl = torch.cat(branch3x3dbl, 1)
+
+        # Patch: Tensorflow's average pool does not use the padded zero's in
+        # its average calculation
+        branch_pool = F.avg_pool2d(x, kernel_size=3, stride=1, padding=1, count_include_pad=False)
+        branch_pool = self.branch_pool(branch_pool)
+
+        outputs = [branch1x1, branch3x3, branch3x3dbl, branch_pool]
+        return torch.cat(outputs, 1)
+
+
+class FIDInceptionE_2(models.inception.InceptionE):
+    """Second InceptionE block patched for FID computation"""
+
+    def __init__(self, in_channels):
+        super(FIDInceptionE_2, self).__init__(in_channels)
+
+    def forward(self, x):
+        branch1x1 = self.branch1x1(x)
+
+        branch3x3 = self.branch3x3_1(x)
+        branch3x3 = [
+            self.branch3x3_2a(branch3x3),
+            self.branch3x3_2b(branch3x3),
+        ]
+        branch3x3 = torch.cat(branch3x3, 1)
+
+        branch3x3dbl = self.branch3x3dbl_1(x)
+        branch3x3dbl = self.branch3x3dbl_2(branch3x3dbl)
+        branch3x3dbl = [
+            self.branch3x3dbl_3a(branch3x3dbl),
+            self.branch3x3dbl_3b(branch3x3dbl),
+        ]
+        branch3x3dbl = torch.cat(branch3x3dbl, 1)
+
+        # Patch: The FID Inception model uses max pooling instead of average
+        # pooling. This is likely an error in this specific Inception
+        # implementation, as other Inception models use average pooling here
+        # (which matches the description in the paper).
+        branch_pool = F.max_pool2d(x, kernel_size=3, stride=1, padding=1)
+        branch_pool = self.branch_pool(branch_pool)
+
+        outputs = [branch1x1, branch3x3, branch3x3dbl, branch_pool]
+        return torch.cat(outputs, 1)

BasicSR/basicsr/archs/rcan_arch.py

+import torch
+from torch import nn as nn
+
+from basicsr.utils.registry import ARCH_REGISTRY
+from .arch_util import Upsample, make_layer
+
+
+class ChannelAttention(nn.Module):
+    """Channel attention used in RCAN.
+
+    Args:
+        num_feat (int): Channel number of intermediate features.
+        squeeze_factor (int): Channel squeeze factor. Default: 16.
+    """
+
+    def __init__(self, num_feat, squeeze_factor=16):
+        super(ChannelAttention, self).__init__()
+        self.attention = nn.Sequential(
+            nn.AdaptiveAvgPool2d(1), nn.Conv2d(num_feat, num_feat // squeeze_factor, 1, padding=0),
+            nn.ReLU(inplace=True), nn.Conv2d(num_feat // squeeze_factor, num_feat, 1, padding=0), nn.Sigmoid())
+
+    def forward(self, x):
+        y = self.attention(x)
+        return x * y
+
+
+class RCAB(nn.Module):
+    """Residual Channel Attention Block (RCAB) used in RCAN.
+
+    Args:
+        num_feat (int): Channel number of intermediate features.
+        squeeze_factor (int): Channel squeeze factor. Default: 16.
+        res_scale (float): Scale the residual. Default: 1.
+    """
+
+    def __init__(self, num_feat, squeeze_factor=16, res_scale=1):
+        super(RCAB, self).__init__()
+        self.res_scale = res_scale
+
+        self.rcab = nn.Sequential(
+            nn.Conv2d(num_feat, num_feat, 3, 1, 1), nn.ReLU(True), nn.Conv2d(num_feat, num_feat, 3, 1, 1),
+            ChannelAttention(num_feat, squeeze_factor))
+
+    def forward(self, x):
+        res = self.rcab(x) * self.res_scale
+        return res + x
+
+
+class ResidualGroup(nn.Module):
+    """Residual Group of RCAB.
+
+    Args:
+        num_feat (int): Channel number of intermediate features.
+        num_block (int): Block number in the body network.
+        squeeze_factor (int): Channel squeeze factor. Default: 16.
+        res_scale (float): Scale the residual. Default: 1.
+    """
+
+    def __init__(self, num_feat, num_block, squeeze_factor=16, res_scale=1):
+        super(ResidualGroup, self).__init__()
+
+        self.residual_group = make_layer(
+            RCAB, num_block, num_feat=num_feat, squeeze_factor=squeeze_factor, res_scale=res_scale)
+        self.conv = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+
+    def forward(self, x):
+        res = self.conv(self.residual_group(x))
+        return res + x
+
+
+@ARCH_REGISTRY.register()
+class RCAN(nn.Module):
+    """Residual Channel Attention Networks.
+
+    ``Paper: Image Super-Resolution Using Very Deep Residual Channel Attention Networks``
+
+    Reference: https://github.com/yulunzhang/RCAN
+
+    Args:
+        num_in_ch (int): Channel number of inputs.
+        num_out_ch (int): Channel number of outputs.
+        num_feat (int): Channel number of intermediate features.
+            Default: 64.
+        num_group (int): Number of ResidualGroup. Default: 10.
+        num_block (int): Number of RCAB in ResidualGroup. Default: 16.
+        squeeze_factor (int): Channel squeeze factor. Default: 16.
+        upscale (int): Upsampling factor. Support 2^n and 3.
+            Default: 4.
+        res_scale (float): Used to scale the residual in residual block.
+            Default: 1.
+        img_range (float): Image range. Default: 255.
+        rgb_mean (tuple[float]): Image mean in RGB orders.
+            Default: (0.4488, 0.4371, 0.4040), calculated from DIV2K dataset.
+    """
+
+    def __init__(self,
+                 num_in_ch,
+                 num_out_ch,
+                 num_feat=64,
+                 num_group=10,
+                 num_block=16,
+                 squeeze_factor=16,
+                 upscale=4,
+                 res_scale=1,
+                 img_range=255.,
+                 rgb_mean=(0.4488, 0.4371, 0.4040)):
+        super(RCAN, self).__init__()
+
+        self.img_range = img_range
+        self.mean = torch.Tensor(rgb_mean).view(1, 3, 1, 1)
+
+        self.conv_first = nn.Conv2d(num_in_ch, num_feat, 3, 1, 1)
+        self.body = make_layer(
+            ResidualGroup,
+            num_group,
+            num_feat=num_feat,
+            num_block=num_block,
+            squeeze_factor=squeeze_factor,
+            res_scale=res_scale)
+        self.conv_after_body = nn.Conv2d(num_feat, num_feat, 3, 1, 1)
+        self.upsample = Upsample(upscale, num_feat)
+        self.conv_last = nn.Conv2d(num_feat, num_out_ch, 3, 1, 1)
+
+    def forward(self, x):
+        self.mean = self.mean.type_as(x)
+
+        x = (x - self.mean) * self.img_range
+        x = self.conv_first(x)
+        res = self.conv_after_body(self.body(x))
+        res += x
+
+        x = self.conv_last(self.upsample(res))
+        x = x / self.img_range + self.mean
+
+        return x