Merge branch 'main' of https://github.com/huggingface/diffusers into main

Makefile

@@ -3,7 +3,7 @@
 # make sure to test the local checkout in scripts and not the pre-installed one (don't use quotes!)
 export PYTHONPATH = src
 
-check_dirs := tests src utils
+check_dirs := examples tests src utils
 
 modified_only_fixup:
 	$(eval modified_py_files := $(shell python utils/get_modified_files.py $(check_dirs)))

_

+# 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.
+
+
+import torch
+
+import tqdm
+
+from ..pipeline_utils import DiffusionPipeline
+
+
+class PNDM(DiffusionPipeline):
+    def __init__(self, unet, noise_scheduler):
+        super().__init__()
+        noise_scheduler = noise_scheduler.set_format("pt")
+        self.register_modules(unet=unet, noise_scheduler=noise_scheduler)
+
+    def __call__(self, batch_size=1, generator=None, torch_device=None, num_inference_steps=50):
+        # eta corresponds to η in paper and should be between [0, 1]
+        if torch_device is None:
+            torch_device = "cuda" if torch.cuda.is_available() else "cpu"
+
+        num_trained_timesteps = self.noise_scheduler.timesteps
+        inference_step_times = range(0, num_trained_timesteps, num_trained_timesteps // num_inference_steps)
+
+        self.unet.to(torch_device)
+
+        # Sample gaussian noise to begin loop
+        image = torch.randn(
+            (batch_size, self.unet.in_channels, self.unet.resolution, self.unet.resolution),
+            generator=generator,
+        )
+        image = image.to(torch_device)
+
+        seq = list(inference_step_times)
+        seq_next = [-1] + list(seq[:-1])
+        model = self.unet
+
+        warmup_steps = [len(seq) - (i // 4 + 1) for i in range(3 * 4)]
+
+        ets = []
+        prev_image = image
+        for i, step_idx in enumerate(warmup_steps):
+            i = seq[step_idx]
+            j = seq_next[step_idx]
+
+            t = (torch.ones(image.shape[0]) * i)
+            t_next = (torch.ones(image.shape[0]) * j)
+
+            residual = model(image.to("cuda"), t.to("cuda"))
+            residual = residual.to("cpu")
+
+            image = image.to("cpu")
+            image = self.noise_scheduler.transfer(prev_image.to("cpu"), t_list[0], t_list[1], residual)
+
+            if i % 4 == 0:
+                ets.append(residual)
+                prev_image = image
+
+        for 
+
+        ets = []
+        step_idx = len(seq) - 1
+        while step_idx >= 0:
+            i = seq[step_idx]
+            j = seq_next[step_idx]
+
+            t = (torch.ones(image.shape[0]) * i)
+            t_next = (torch.ones(image.shape[0]) * j)
+
+            residual = model(image.to("cuda"), t.to("cuda"))
+            residual = residual.to("cpu")
+
+            t_list = [t, (t+t_next)/2, t_next]
+
+            ets.append(residual)
+            if len(ets) <= 3:
+                image = image.to("cpu")
+                x_2 = self.noise_scheduler.transfer(image.to("cpu"), t_list[0], t_list[1], residual)
+
+                e_2 = model(x_2.to("cuda"), t_list[1].to("cuda")).to("cpu")
+                x_3 = self.noise_scheduler.transfer(image, t_list[0], t_list[1], e_2)
+                e_3 = model(x_3.to("cuda"), t_list[1].to("cuda")).to("cpu")
+                x_4 = self.noise_scheduler.transfer(image, t_list[0], t_list[2], e_3)
+                e_4 = model(x_4.to("cuda"), t_list[2].to("cuda")).to("cpu")
+                residual = (1 / 6) * (residual + 2 * e_2 + 2 * e_3 + e_4)
+            else:
+                residual = (1 / 24) * (55 * ets[-1] - 59 * ets[-2] + 37 * ets[-3] - 9 * ets[-4])
+
+            img_next = self.noise_scheduler.transfer(image.to("cpu"), t, t_next, residual)
+            image = img_next
+
+            step_idx = step_idx - 1
+
+#            if len(prev_noises) in [1, 2]:
+#                t = (t + t_next) / 2
+#            elif len(prev_noises) == 3:
+#                t = t_next / 2
+
+#            if len(prev_noises) == 0:
+#                ets.append(residual)
+#
+#            if len(ets) > 3:
+#                residual = (1 / 24) * (55 * ets[-1] - 59 * ets[-2] + 37 * ets[-3] - 9 * ets[-4])
+#                step_idx = step_idx - 1
+#            elif len(ets) <= 3 and len(prev_noises) == 3:
+#                residual = (1 / 6) * (prev_noises[-3] + 2 * prev_noises[-2] + 2 * prev_noises[-1] + residual)
+#                prev_noises = []
+#                step_idx = step_idx - 1
+#            elif len(ets) <= 3 and len(prev_noises) < 3:
+#                prev_noises.append(residual)
+#                if len(prev_noises) < 2:
+#                    t_next = (t + t_next) / 2
+#
+#            image = self.noise_scheduler.transfer(image.to("cpu"), t, t_next, residual)
+
+        return image
+
+        # See formulas (12) and (16) of DDIM paper https://arxiv.org/pdf/2010.02502.pdf
+        # Ideally, read DDIM paper in-detail understanding
+
+        # Notation (<variable name> -> <name in paper>
+        # - pred_noise_t -> e_theta(x_t, t)
+        # - pred_original_image -> f_theta(x_t, t) or x_0
+        # - std_dev_t -> sigma_t
+        # - eta -> η
+        # - pred_image_direction -> "direction pointingc to x_t"
+        # - pred_prev_image -> "x_t-1"
+#        for t in tqdm.tqdm(reversed(range(num_inference_steps)), total=num_inference_steps):
+            # 1. predict noise residual
+#            with torch.no_grad():
+#                residual = self.unet(image, inference_step_times[t])
+#
+            # 2. predict previous mean of image x_t-1
+#            pred_prev_image = self.noise_scheduler.step(residual, image, t, num_inference_steps, eta)
+#
+            # 3. optionally sample variance
+#            variance = 0
+#            if eta > 0:
+#                noise = torch.randn(image.shape, generator=generator).to(image.device)
+#                variance = self.noise_scheduler.get_variance(t, num_inference_steps).sqrt() * eta * noise
+#
+            # 4. set current image to prev_image: x_t -> x_t-1
+#            image = pred_prev_image + variance

src/diffusers/trainers/training_ddpm.py → examples/training_ddpm.py

@@ -8,14 +8,23 @@ import PIL.Image
 from accelerate import Accelerator
 from datasets import load_dataset
 from diffusers import DDPM, DDPMScheduler, UNetModel
-from torchvision.transforms import CenterCrop, Compose, Lambda, RandomHorizontalFlip, Resize, ToTensor
+from torchvision.transforms import (
+    Compose,
+    InterpolationMode,
+    Lambda,
+    RandomCrop,
+    RandomHorizontalFlip,
+    RandomVerticalFlip,
+    Resize,
+    ToTensor,
+)
 from tqdm.auto import tqdm
 from transformers import get_linear_schedule_with_warmup
 
 
 def set_seed(seed):
-    torch.backends.cudnn.deterministic = True
-    torch.backends.cudnn.benchmark = False
+    # torch.backends.cudnn.deterministic = True
+    # torch.backends.cudnn.benchmark = False
     torch.manual_seed(seed)
     torch.cuda.manual_seed_all(seed)
     np.random.seed(seed)
@@ -30,13 +39,13 @@ model = UNetModel(
     attn_resolutions=(16,),
     ch=128,
     ch_mult=(1, 2, 2, 2),
-    dropout=0.1,
+    dropout=0.0,
     num_res_blocks=2,
     resamp_with_conv=True,
-    resolution=32
+    resolution=32,
 )
 noise_scheduler = DDPMScheduler(timesteps=1000)
-optimizer = torch.optim.Adam(model.parameters(), lr=0.0002)
+optimizer = torch.optim.Adam(model.parameters(), lr=3e-4)
 
 num_epochs = 100
 batch_size = 64
@@ -44,14 +53,15 @@ gradient_accumulation_steps = 2
 
 augmentations = Compose(
     [
-        Resize(32),
-        CenterCrop(32),
+        Resize(32, interpolation=InterpolationMode.BILINEAR),
         RandomHorizontalFlip(),
+        RandomVerticalFlip(),
+        RandomCrop(32),
         ToTensor(),
         Lambda(lambda x: x * 2 - 1),
     ]
 )
-dataset = load_dataset("huggan/pokemon", split="train")
+dataset = load_dataset("huggan/flowers-102-categories", split="train")
 
 
 def transforms(examples):
@@ -59,24 +69,24 @@ def transforms(examples):
     return {"input": images}
 
 
-dataset = dataset.shuffle(seed=0)
 dataset.set_transform(transforms)
-train_dataloader = torch.utils.data.DataLoader(dataset, batch_size=batch_size, shuffle=False)
+train_dataloader = torch.utils.data.DataLoader(dataset, batch_size=batch_size, shuffle=True)
 
-#lr_scheduler = get_linear_schedule_with_warmup(
-#    optimizer=optimizer,
-#    num_warmup_steps=1000,
-#    num_training_steps=(len(train_dataloader) * num_epochs) // gradient_accumulation_steps,
-#)
+lr_scheduler = get_linear_schedule_with_warmup(
+    optimizer=optimizer,
+    num_warmup_steps=500,
+    num_training_steps=(len(train_dataloader) * num_epochs) // gradient_accumulation_steps,
+)
 
-model, optimizer, train_dataloader = accelerator.prepare(
-    model, optimizer, train_dataloader
+model, optimizer, train_dataloader, lr_scheduler = accelerator.prepare(
+    model, optimizer, train_dataloader, lr_scheduler
 )
 
 for epoch in range(num_epochs):
     model.train()
     pbar = tqdm(total=len(train_dataloader), unit="ba")
     pbar.set_description(f"Epoch {epoch}")
+    losses = []
     for step, batch in enumerate(train_dataloader):
         clean_images = batch["input"]
         noisy_images = torch.empty_like(clean_images)
@@ -101,10 +111,12 @@ for epoch in range(num_epochs):
             accelerator.backward(loss)
             torch.nn.utils.clip_grad_norm_(model.parameters(), 1.0)
             optimizer.step()
-            # lr_scheduler.step()
+            lr_scheduler.step()
             optimizer.zero_grad()
+        loss = loss.detach().item()
+        losses.append(loss)
         pbar.update(1)
-        pbar.set_postfix(loss=loss.detach().item(), lr=optimizer.param_groups[0]["lr"])
+        pbar.set_postfix(loss=loss, avg_loss=np.mean(losses), lr=optimizer.param_groups[0]["lr"])
 
         optimizer.step()
 
@@ -124,5 +136,5 @@ for epoch in range(num_epochs):
         image_pil = PIL.Image.fromarray(image_processed[0])
 
         # save image
-        pipeline.save_pretrained("./poke-ddpm")
-        image_pil.save(f"./poke-ddpm/test_{epoch}.png")
+        pipeline.save_pretrained("./flowers-ddpm")
+        image_pil.save(f"./flowers-ddpm/test_{epoch}.png")

src/diffusers/configuration_utils.py

@@ -225,11 +225,8 @@ class ConfigMixin:
             text = reader.read()
         return json.loads(text)
 
-    # def __eq__(self, other):
-    #    return self.__dict__ == other.__dict__
-
-    # def __repr__(self):
-    #    return f"{self.__class__.__name__} {self.to_json_string()}"
+    def __repr__(self):
+       return f"{self.__class__.__name__} {self.to_json_string()}"
 
     @property
     def config(self) -> Dict[str, Any]:

src/diffusers/pipelines/pipeline_glide.py

@@ -832,12 +832,12 @@ class GLIDE(DiffusionPipeline):
 
         # 1. Sample gaussian noise
         batch_size = 2  # second image is empty for classifier-free guidance
-        image = self.text_noise_scheduler.sample_noise(
-            (batch_size, self.text_unet.in_channels, 64, 64), device=torch_device, generator=generator
-        )
+        image = torch.randn(
+            (batch_size, self.text_unet.in_channels, 64, 64), generator=generator
+        ).to(torch_device)
 
         # 2. Encode tokens
-        # an empty input is needed to guide the model away from (
+        # an empty input is needed to guide the model away from it
         inputs = self.tokenizer([prompt, ""], padding="max_length", max_length=128, return_tensors="pt")
         input_ids = inputs["input_ids"].to(torch_device)
         attention_mask = inputs["attention_mask"].to(torch_device)
@@ -850,7 +850,7 @@ class GLIDE(DiffusionPipeline):
             mean, variance, log_variance, pred_xstart = self.p_mean_variance(
                 text_model_fn, self.text_noise_scheduler, image, t, transformer_out=transformer_out
             )
-            noise = self.text_noise_scheduler.sample_noise(image.shape, device=torch_device, generator=generator)
+            noise = torch.randn(image.shape, generator=generator).to(torch_device)
             nonzero_mask = (t != 0).float().view(-1, *([1] * (len(image.shape) - 1)))  # no noise when t == 0
             image = mean + nonzero_mask * torch.exp(0.5 * log_variance) * noise
 
@@ -873,8 +873,8 @@ class GLIDE(DiffusionPipeline):
                 self.upscale_unet.resolution,
             ),
             generator=generator,
-        )
-        image = image.to(torch_device) * upsample_temp
+        ).to(torch_device)
+        image = image * upsample_temp
 
         num_trained_timesteps = self.upscale_noise_scheduler.timesteps
         inference_step_times = range(0, num_trained_timesteps, num_trained_timesteps // num_inference_steps_upscale)
@@ -896,7 +896,7 @@ class GLIDE(DiffusionPipeline):
             # 3. optionally sample variance
             variance = 0
             if eta > 0:
-                noise = torch.randn(image.shape, generator=generator).to(image.device)
+                noise = torch.randn(image.shape, generator=generator).to(torch_device)
                 variance = (
                     self.upscale_noise_scheduler.get_variance(t, num_inference_steps_upscale).sqrt() * eta * noise
                 )

src/diffusers/pipelines/pipeline_pndm.py

@@ -28,13 +28,11 @@ class PNDM(DiffusionPipeline):
         self.register_modules(unet=unet, noise_scheduler=noise_scheduler)
 
     def __call__(self, batch_size=1, generator=None, torch_device=None, num_inference_steps=50):
-        # eta corresponds to η in paper and should be between [0, 1]
+        # For more information on the sampling method you can take a look at Algorithm 2 of
+        # the official paper: https://arxiv.org/pdf/2202.09778.pdf
         if torch_device is None:
             torch_device = "cuda" if torch.cuda.is_available() else "cpu"
 
-        num_trained_timesteps = self.noise_scheduler.timesteps
-        inference_step_times = range(0, num_trained_timesteps, num_trained_timesteps // num_inference_steps)
-
         self.unet.to(torch_device)
 
         # Sample gaussian noise to begin loop
@@ -44,91 +42,18 @@ class PNDM(DiffusionPipeline):
         )
         image = image.to(torch_device)
 
-        seq = list(inference_step_times)
-        seq_next = [-1] + list(seq[:-1])
-        model = self.unet
-
-        ets = []
-        prev_noises = []
-        step_idx = len(seq) - 1
-        while step_idx >= 0:
-            i = seq[step_idx]
-            j = seq_next[step_idx]
-
-            t = (torch.ones(image.shape[0]) * i)
-            t_next = (torch.ones(image.shape[0]) * j)
-
-            residual = model(image.to("cuda"), t.to("cuda"))
-            residual = residual.to("cpu")
+        warmup_time_steps = self.noise_scheduler.get_warmup_time_steps(num_inference_steps)
+        for t in tqdm.tqdm(range(len(warmup_time_steps))):
+            t_orig = warmup_time_steps[t]
+            residual = self.unet(image, t_orig)
 
-            t_list = [t, (t+t_next)/2, t_next]
+            image = self.noise_scheduler.step_prk(residual, image, t, num_inference_steps)
 
-            ets.append(residual)
-            if len(ets) <= 3:
-                image = image.to("cpu")
-                x_2 = self.noise_scheduler.transfer(image.to("cpu"), t_list[0], t_list[1], residual)
+        timesteps = self.noise_scheduler.get_time_steps(num_inference_steps)
+        for t in tqdm.tqdm(range(len(timesteps))):
+            t_orig = timesteps[t]
+            residual = self.unet(image, t_orig)
 
-                e_2 = model(x_2.to("cuda"), t_list[1].to("cuda")).to("cpu")
-                x_3 = self.noise_scheduler.transfer(image, t_list[0], t_list[1], e_2)
-                e_3 = model(x_3.to("cuda"), t_list[1].to("cuda")).to("cpu")
-                x_4 = self.noise_scheduler.transfer(image, t_list[0], t_list[2], e_3)
-                e_4 = model(x_4.to("cuda"), t_list[2].to("cuda")).to("cpu")
-                residual = (1 / 6) * (residual + 2 * e_2 + 2 * e_3 + e_4)
-            else:
-                residual = (1 / 24) * (55 * ets[-1] - 59 * ets[-2] + 37 * ets[-3] - 9 * ets[-4])
-
-            img_next = self.noise_scheduler.transfer(image.to("cpu"), t, t_next, residual)
-            image = img_next
-
-            step_idx = step_idx - 1
-
-#            if len(prev_noises) in [1, 2]:
-#                t = (t + t_next) / 2
-#            elif len(prev_noises) == 3:
-#                t = t_next / 2
-
-#            if len(prev_noises) == 0:
-#                ets.append(residual)
-#
-#            if len(ets) > 3:
-#                residual = (1 / 24) * (55 * ets[-1] - 59 * ets[-2] + 37 * ets[-3] - 9 * ets[-4])
-#                step_idx = step_idx - 1
-#            elif len(ets) <= 3 and len(prev_noises) == 3:
-#                residual = (1 / 6) * (prev_noises[-3] + 2 * prev_noises[-2] + 2 * prev_noises[-1] + residual)
-#                prev_noises = []
-#                step_idx = step_idx - 1
-#            elif len(ets) <= 3 and len(prev_noises) < 3:
-#                prev_noises.append(residual)
-#                if len(prev_noises) < 2:
-#                    t_next = (t + t_next) / 2
-#
-#            image = self.noise_scheduler.transfer(image.to("cpu"), t, t_next, residual)
+            image = self.noise_scheduler.step_plms(residual, image, t, num_inference_steps)
 
         return image
-
-        # See formulas (12) and (16) of DDIM paper https://arxiv.org/pdf/2010.02502.pdf
-        # Ideally, read DDIM paper in-detail understanding
-
-        # Notation (<variable name> -> <name in paper>
-        # - pred_noise_t -> e_theta(x_t, t)
-        # - pred_original_image -> f_theta(x_t, t) or x_0
-        # - std_dev_t -> sigma_t
-        # - eta -> η
-        # - pred_image_direction -> "direction pointingc to x_t"
-        # - pred_prev_image -> "x_t-1"
-#        for t in tqdm.tqdm(reversed(range(num_inference_steps)), total=num_inference_steps):
-            # 1. predict noise residual
-#            with torch.no_grad():
-#                residual = self.unet(image, inference_step_times[t])
-#
-            # 2. predict previous mean of image x_t-1
-#            pred_prev_image = self.noise_scheduler.step(residual, image, t, num_inference_steps, eta)
-#
-            # 3. optionally sample variance
-#            variance = 0
-#            if eta > 0:
-#                noise = torch.randn(image.shape, generator=generator).to(image.device)
-#                variance = self.noise_scheduler.get_variance(t, num_inference_steps).sqrt() * eta * noise
-#
-            # 4. set current image to prev_image: x_t -> x_t-1
-#            image = pred_prev_image + variance

src/diffusers/schedulers/scheduling_pndm.py

@@ -55,22 +55,17 @@ class PNDMScheduler(SchedulerMixin, ConfigMixin):
 
         self.set_format(tensor_format=tensor_format)
 
-    #        self.register_buffer("betas", betas.to(torch.float32))
-    #        self.register_buffer("alphas", alphas.to(torch.float32))
-    #        self.register_buffer("alphas_cumprod", alphas_cumprod.to(torch.float32))
-
-    #        alphas_cumprod_prev = torch.nn.functional.pad(alphas_cumprod[:-1], (1, 0), value=1.0)
-    # TODO(PVP) - check how much of these is actually necessary!
-    # LDM only uses "fixed_small"; glide seems to use a weird mix of the two, ...
-    # https://github.com/openai/glide-text2im/blob/69b530740eb6cef69442d6180579ef5ba9ef063e/glide_text2im/gaussian_diffusion.py#L246
-    #        variance = betas * (1.0 - alphas_cumprod_prev) / (1.0 - alphas_cumprod)
-    #        if variance_type == "fixed_small":
-    #            log_variance = torch.log(variance.clamp(min=1e-20))
-    #        elif variance_type == "fixed_large":
-    #            log_variance = torch.log(torch.cat([variance[1:2], betas[1:]], dim=0))
-    #
-    #
-    #        self.register_buffer("log_variance", log_variance.to(torch.float32))
+        # For now we only support F-PNDM, i.e. the runge-kutta method
+        # For more information on the algorithm please take a look at the paper: https://arxiv.org/pdf/2202.09778.pdf
+        # mainly at equations (12) and (13) and the Algorithm 2.
+        self.pndm_order = 4
+
+        # running values
+        self.cur_residual = 0
+        self.cur_image = None
+        self.ets = []
+        self.warmup_time_steps = {}
+        self.time_steps = {}
 
     def get_alpha(self, time_step):
         return self.alphas[time_step]
@@ -83,51 +78,64 @@ class PNDMScheduler(SchedulerMixin, ConfigMixin):
             return self.one
         return self.alphas_cumprod[time_step]
 
-    def step(self, img, t_start, t_end, model, ets):
-#        img_next = self.method(img_n, t_start, t_end, model, self.alphas_cump, self.ets)
-#def gen_order_4(img, t, t_next, model, alphas_cump, ets):
-        t_next, t = t_start, t_end
+    def get_warmup_time_steps(self, num_inference_steps):
+        if num_inference_steps in self.warmup_time_steps:
+            return self.warmup_time_steps[num_inference_steps]
 
-        noise_ = model(img.to("cuda"), t.to("cuda"))
-        noise_ = noise_.to("cpu")
+        inference_step_times = list(range(0, self.timesteps, self.timesteps // num_inference_steps))
 
-        t_list = [t, (t+t_next)/2, t_next]
-        if len(ets) > 2:
-            ets.append(noise_)
-            noise = (1 / 24) * (55 * ets[-1] - 59 * ets[-2] + 37 * ets[-3] - 9 * ets[-4])
-        else:
-            noise = self.runge_kutta(img, t_list, model, ets, noise_)
+        warmup_time_steps = np.array(inference_step_times[-self.pndm_order:]).repeat(2) + np.tile(np.array([0, self.timesteps // num_inference_steps // 2]), self.pndm_order)
+        self.warmup_time_steps[num_inference_steps] = list(reversed(warmup_time_steps[:-1].repeat(2)[1:-1]))
+
+        return self.warmup_time_steps[num_inference_steps]
+
+    def get_time_steps(self, num_inference_steps):
+        if num_inference_steps in self.time_steps:
+            return self.time_steps[num_inference_steps]
 
-        img_next = self.transfer(img.to("cpu"), t, t_next, noise)
-        return img_next, ets
+        inference_step_times = list(range(0, self.timesteps, self.timesteps // num_inference_steps))
+        self.time_steps[num_inference_steps] = list(reversed(inference_step_times[:-3]))
 
-    def runge_kutta(self, x, t_list, model, ets, noise_):
-        model = model.to("cuda")
-        x = x.to("cpu")
+        return self.time_steps[num_inference_steps]
 
-        e_1 = noise_
-        ets.append(e_1)
-        x_2 = self.transfer(x, t_list[0], t_list[1], e_1)
+    def step_prk(self, residual, image, t, num_inference_steps):
+        # TODO(Patrick) - need to rethink whether the "warmup" way is the correct API design here
+        warmup_time_steps = self.get_warmup_time_steps(num_inference_steps)
 
-        e_2 = model(x_2.to("cuda"), t_list[1].to("cuda"))
-        e_2 = e_2.to("cpu")
-        x_3 = self.transfer(x, t_list[0], t_list[1], e_2)
+        t_prev = warmup_time_steps[t // 4 * 4]
+        t_next = warmup_time_steps[min(t + 1, len(warmup_time_steps) - 1)]
 
-        e_3 = model(x_3.to("cuda"), t_list[1].to("cuda"))
-        e_3 = e_3.to("cpu")
-        x_4 = self.transfer(x, t_list[0], t_list[2], e_3)
+        if t % 4 == 0:
+            self.cur_residual += 1 / 6 * residual
+            self.ets.append(residual)
+            self.cur_image = image
+        elif (t - 1) % 4 == 0:
+            self.cur_residual += 1 / 3 * residual
+        elif (t - 2) % 4 == 0:
+            self.cur_residual += 1 / 3 * residual
+        elif (t - 3) % 4 == 0:
+            residual = self.cur_residual + 1 / 6 * residual
+            self.cur_residual = 0
 
-        e_4 = model(x_4.to("cuda"), t_list[2].to("cuda"))
-        e_4 = e_4.to("cpu")
+        return self.transfer(self.cur_image, t_prev, t_next, residual)
 
-        et = (1 / 6) * (e_1 + 2 * e_2 + 2 * e_3 + e_4)
+    def step_plms(self, residual, image, t, num_inference_steps):
+        timesteps = self.get_time_steps(num_inference_steps)
 
-        return et
+        t_prev = timesteps[t]
+        t_next = timesteps[min(t + 1, len(timesteps) - 1)]
+        self.ets.append(residual)
+
+        residual = (1 / 24) * (55 * self.ets[-1] - 59 * self.ets[-2] + 37 * self.ets[-3] - 9 * self.ets[-4])
+
+        return self.transfer(image, t_prev, t_next, residual)
 
     def transfer(self, x, t, t_next, et):
-        alphas_cump = self.alphas_cumprod
-        at = alphas_cump[t.long() + 1].view(-1, 1, 1, 1)
-        at_next = alphas_cump[t_next.long() + 1].view(-1, 1, 1, 1)
+        # TODO(Patrick): clean up to be compatible with numpy and give better names
+
+        alphas_cump = self.alphas_cumprod.to(x.device)
+        at = alphas_cump[t + 1].view(-1, 1, 1, 1)
+        at_next = alphas_cump[t_next + 1].view(-1, 1, 1, 1)
 
         x_delta = (at_next - at) * ((1 / (at.sqrt() * (at.sqrt() + at_next.sqrt()))) * x - 1 / (at.sqrt() * (((1 - at_next) * at).sqrt() + ((1 - at) * at_next).sqrt())) * et)
 

tests/test_modeling_utils.py

@@ -19,7 +19,7 @@ import unittest
 
 import torch
 
-from diffusers import DDIM, DDPM, BDDM, DDIMScheduler, DDPMScheduler, LatentDiffusion, UNetModel, PNDM, PNDMScheduler
+from diffusers import DDIM, DDPM, PNDM, GLIDE, BDDM, DDIMScheduler, DDPMScheduler, LatentDiffusion, PNDMScheduler, UNetModel
 from diffusers.configuration_utils import ConfigMixin
 from diffusers.pipeline_utils import DiffusionPipeline
 from diffusers.pipelines.pipeline_bddm import DiffWave
@@ -228,4 +228,18 @@ class PipelineTesterMixin(unittest.TestCase):
             bddm.save_pretrained(tmpdirname)
             _ = BDDM.from_pretrained(tmpdirname)
             # check if the same works using the DifusionPipeline class
-            _ = DiffusionPipeline.from_pretrained(tmpdirname)
+            _ = DiffusionPipeline.from_pretrained(tmpdirname)
\ No newline at end of file
+    @slow
+    def test_glide_text2img(self):
+        model_id = "fusing/glide-base"
+        glide = GLIDE.from_pretrained(model_id)
+
+        prompt = "a pencil sketch of a corgi"
+        generator = torch.manual_seed(0)
+        image = glide(prompt, generator=generator, num_inference_steps_upscale=20)
+
+        image_slice = image[0, :3, :3, -1].cpu()
+
+        assert image.shape == (1, 256, 256, 3)
+        expected_slice = torch.tensor([0.7119, 0.7073, 0.6460, 0.7780, 0.7423, 0.6926, 0.7378, 0.7189, 0.7784])
+        assert (image_slice.flatten() - expected_slice).abs().max() < 1e-2