Merge pull request #1 from huggingface/add-glide

Add glide modeling files

models/vision/glide/modeling_glide.py

+# Copyright 2022 The HuggingFace Team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+
+# limitations under the License.
+
+
+from diffusers import DiffusionPipeline
+from diffusers import UNetGLIDEModel
+
+import tqdm
+import torch
+
+
+class GLIDE(DiffusionPipeline):
+    def __init__(self, unet: UNetGLIDEModel, noise_scheduler):
+        super().__init__()
+        self.register_modules(unet=unet, noise_scheduler=noise_scheduler)
+
+    def __call__(self, generator=None, torch_device=None):
+        torch_device = "cuda" if torch.cuda.is_available() else "cpu"
+
+        self.unet.to(torch_device)
+        # 1. Sample gaussian noise
+        image = self.noise_scheduler.sample_noise((1, self.unet.in_channels, self.unet.resolution, self.unet.resolution), device=torch_device, generator=generator)
+        for t in tqdm.tqdm(reversed(range(len(self.noise_scheduler))), total=len(self.noise_scheduler)):
+            # i) define coefficients for time step t
+            clip_image_coeff = 1 / torch.sqrt(self.noise_scheduler.get_alpha_prod(t))
+            clip_noise_coeff = torch.sqrt(1 / self.noise_scheduler.get_alpha_prod(t) - 1)
+            image_coeff = (1 - self.noise_scheduler.get_alpha_prod(t - 1)) * torch.sqrt(self.noise_scheduler.get_alpha(t)) / (1 - self.noise_scheduler.get_alpha_prod(t))
+            clip_coeff = torch.sqrt(self.noise_scheduler.get_alpha_prod(t - 1)) * self.noise_scheduler.get_beta(t) / (1 - self.noise_scheduler.get_alpha_prod(t))
+
+            # ii) predict noise residual
+            with torch.no_grad():
+                noise_residual = self.unet(image, t)
+
+            # iii) compute predicted image from residual
+            # See 2nd formula at https://github.com/hojonathanho/diffusion/issues/5#issue-896554416 for comparison
+            pred_mean = clip_image_coeff * image - clip_noise_coeff * noise_residual
+            pred_mean = torch.clamp(pred_mean, -1, 1)
+            prev_image = clip_coeff * pred_mean + image_coeff * image
+
+            # iv) sample variance
+            prev_variance = self.noise_scheduler.sample_variance(t, prev_image.shape, device=torch_device, generator=generator)
+
+            # v) sample  x_{t-1} ~ N(prev_image, prev_variance)
+            sampled_prev_image = prev_image + prev_variance
+            image = sampled_prev_image
+
+        return image

src/diffusers/__init__.py

@@ -6,5 +6,6 @@ __version__ = "0.0.1"
 
 from .modeling_utils import ModelMixin
 from .models.unet import UNetModel
+from .models.unet_glide import UNetGLIDEModel
 from .pipeline_utils import DiffusionPipeline
 from .schedulers.gaussian_ddpm import GaussianDDPMScheduler

src/diffusers/models/__init__.py

@@ -17,3 +17,4 @@
 # limitations under the License.
 
 from .unet import UNetModel
+from .unet_glide import UNetGLIDEModel