Add CycleDiffusion pipeline using Stable Diffusion (#888)

* Add CycleDiffusion pipeline for Stable Diffusion

* Add the option of passing noise to DDIMScheduler

Add the option of providing the noise itself to DDIMScheduler, instead of the random seed generator.

* Update README.md

* Update README.md

* Update pipeline_stable_diffusion_cycle_diffusion.py

* Update pipeline_stable_diffusion_cycle_diffusion.py

* Update pipeline_stable_diffusion_cycle_diffusion.py

* Update pipeline_stable_diffusion_cycle_diffusion.py

* Update scheduling_ddim.py

* Update import format

* Update pipeline_stable_diffusion_cycle_diffusion.py

* Update scheduling_ddim.py

* Update src/diffusers/schedulers/scheduling_ddim.py
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>

* Update src/diffusers/schedulers/scheduling_ddim.py
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>

* Update src/diffusers/schedulers/scheduling_ddim.py
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>

* Update src/diffusers/schedulers/scheduling_ddim.py
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>

* Update src/diffusers/schedulers/scheduling_ddim.py
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>

* Update scheduling_ddim.py

* Update scheduling_ddim.py

* Update scheduling_ddim.py

* add two tests

* Update pipeline_stable_diffusion_cycle_diffusion.py

* Update pipeline_stable_diffusion_cycle_diffusion.py

* Update README.md

* Rename pipeline name as suggested in the latest reviewer comment

* Update test_pipelines.py

* Update test_pipelines.py

* Update test_pipelines.py

* Update pipeline_stable_diffusion_cycle_diffusion.py

* Remove the generator

This generator does not control all randomness during sampling, which can be misleading.

* Update optimal hyperparameters

* Update src/diffusers/pipelines/stable_diffusion/README.md
Co-authored-by: Suraj Patil <surajp815@gmail.com>

* Update src/diffusers/pipelines/stable_diffusion/README.md
Co-authored-by: Suraj Patil <surajp815@gmail.com>

* Update src/diffusers/pipelines/stable_diffusion/README.md
Co-authored-by: Suraj Patil <surajp815@gmail.com>

* Apply suggestions from code review

* uP

* Update src/diffusers/pipelines/stable_diffusion/pipeline_stable_diffusion_cycle_diffusion.py
Co-authored-by: Suraj Patil <surajp815@gmail.com>

* up

* up

* Replace assert with ValueError

* finish docs
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
Co-authored-by: Suraj Patil <surajp815@gmail.com>

docs/source/_toctree.yml

@@ -78,6 +78,8 @@
   - sections:
     - local: api/pipelines/overview
       title: "Overview"
+    - local: api/pipelines/cycle_diffusion
+      title: "Cycle Diffusion"
     - local: api/pipelines/ddim
       title: "DDIM"
     - local: api/pipelines/ddpm

docs/source/api/pipelines/cycle_diffusion.mdx

+<!--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.
+-->
+
+# Cycle Diffusion
+
+## Overview
+
+Cycle Diffusion is a Text-Guided Image-to-Image Generation model proposed in [Unifying Diffusion Models' Latent Space, with Applications to CycleDiffusion and Guidance](https://arxiv.org/abs/2210.05559) by Chen Henry Wu, Fernando De la Torre.
+
+The abstract of the paper is the following:
+
+*Diffusion models have achieved unprecedented performance in generative modeling. The commonly-adopted formulation of the latent code of diffusion models is a sequence of gradually denoised samples, as opposed to the simpler (e.g., Gaussian) latent space of GANs, VAEs, and normalizing flows. This paper provides an alternative, Gaussian formulation of the latent space of various diffusion models, as well as an invertible DPM-Encoder that maps images into the latent space. While our formulation is purely based on the definition of diffusion models, we demonstrate several intriguing consequences. (1) Empirically, we observe that a common latent space emerges from two diffusion models trained independently on related domains. In light of this finding, we propose CycleDiffusion, which uses DPM-Encoder for unpaired image-to-image translation. Furthermore, applying CycleDiffusion to text-to-image diffusion models, we show that large-scale text-to-image diffusion models can be used as zero-shot image-to-image editors. (2) One can guide pre-trained diffusion models and GANs by controlling the latent codes in a unified, plug-and-play formulation based on energy-based models. Using the CLIP model and a face recognition model as guidance, we demonstrate that diffusion models have better coverage of low-density sub-populations and individuals than GANs.*
+
+*Tips*:
+- The Cycle Diffusion pipeline is fully compatible with any [Stable Diffusion](./stable_diffusion) checkpoints
+- Currently Cycle Diffusion only works with the [`DDIMScheduler`].
+
+*Example*:
+
+In the following we should how to best use the [`CycleDiffusionPipeline`]
+
+```python
+import requests
+import torch
+from PIL import Image
+from io import BytesIO
+
+from diffusers import CycleDiffusionPipeline, DDIMScheduler
+
+# load the pipeline
+# make sure you're logged in with `huggingface-cli login`
+model_id_or_path = "CompVis/stable-diffusion-v1-4"
+scheduler = DDIMScheduler.from_config(model_id_or_path, subfolder="scheduler")
+pipe = CycleDiffusionPipeline.from_pretrained(model_id_or_path, scheduler=scheduler).to("cuda")
+
+# let's download an initial image
+url = "https://raw.githubusercontent.com/ChenWu98/cycle-diffusion/main/data/dalle2/An%20astronaut%20riding%20a%20horse.png"
+response = requests.get(url)
+init_image = Image.open(BytesIO(response.content)).convert("RGB")
+init_image = init_image.resize((512, 512))
+init_image.save("horse.png")
+
+# let's specify a prompt
+source_prompt = "An astronaut riding a horse"
+prompt = "An astronaut riding an elephant"
+
+# call the pipeline
+image = pipe(
+    prompt=prompt,
+    source_prompt=source_prompt,
+    init_image=init_image,
+    num_inference_steps=100,
+    eta=0.1,
+    strength=0.8,
+    guidance_scale=2,
+    source_guidance_scale=1,
+).images[0]
+
+image.save("horse_to_elephant.png")
+
+# let's try another example
+# See more samples at the original repo: https://github.com/ChenWu98/cycle-diffusion
+url = "https://raw.githubusercontent.com/ChenWu98/cycle-diffusion/main/data/dalle2/A%20black%20colored%20car.png"
+response = requests.get(url)
+init_image = Image.open(BytesIO(response.content)).convert("RGB")
+init_image = init_image.resize((512, 512))
+init_image.save("black.png")
+
+source_prompt = "A black colored car"
+prompt = "A blue colored car"
+
+# call the pipeline
+torch.manual_seed(0)
+image = pipe(
+    prompt=prompt,
+    source_prompt=source_prompt,
+    init_image=init_image,
+    num_inference_steps=100,
+    eta=0.1,
+    strength=0.85,
+    guidance_scale=3,
+    source_guidance_scale=1,
+).images[0]
+
+image.save("black_to_blue.png")
+```
+
+## CycleDiffusionPipeline
+[[autodoc]] CycleDiffusionPipeline
+	- __call__

docs/source/api/pipelines/overview.mdx

@@ -41,21 +41,24 @@ If you are looking for *official* training examples, please have a look at [exam
 The following table summarizes all officially supported pipelines, their corresponding paper, and if 
 available a colab notebook to directly try them out.
 
+
 | Pipeline | Paper | Tasks | Colab
 |---|---|:---:|:---:|
-| [ddpm](./ddpm) | [**Denoising Diffusion Probabilistic Models**](https://arxiv.org/abs/2006.11239) | Unconditional Image Generation |
-| [ddim](./ddim) | [**Denoising Diffusion Implicit Models**](https://arxiv.org/abs/2010.02502) | Unconditional Image Generation | [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/huggingface/notebooks/blob/main/diffusers/training_example.ipynb)
-| [latent_diffusion](./latent_diffusion) | [**High-Resolution Image Synthesis with Latent Diffusion Models**](https://arxiv.org/abs/2112.10752)| Text-to-Image Generation | 
-| [latent_diffusion_uncond](./latent_diffusion_uncond) | [**High-Resolution Image Synthesis with Latent Diffusion Models**](https://arxiv.org/abs/2112.10752) | Unconditional Image Generation | 
-| [pndm](./pndm) | [**Pseudo Numerical Methods for Diffusion Models on Manifolds**](https://arxiv.org/abs/2202.09778) | Unconditional Image Generation | 
-| [score_sde_ve](./score_sde_ve) | [**Score-Based Generative Modeling through Stochastic Differential Equations**](https://openreview.net/forum?id=PxTIG12RRHS) | Unconditional Image Generation | 
-| [score_sde_vp](./score_sde_vp) | [**Score-Based Generative Modeling through Stochastic Differential Equations**](https://openreview.net/forum?id=PxTIG12RRHS) | Unconditional Image Generation | 
-| [stable_diffusion](./stable_diffusion) | [**Stable Diffusion**](https://stability.ai/blog/stable-diffusion-public-release) | Text-to-Image Generation | [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/huggingface/notebooks/blob/main/diffusers/training_example.ipynb)
-| [stable_diffusion](./stable_diffusion) | [**Stable Diffusion**](https://stability.ai/blog/stable-diffusion-public-release) | Image-to-Image Text-Guided Generation | [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/huggingface/notebooks/blob/main/diffusers/image_2_image_using_diffusers.ipynb)
-| [stable_diffusion](./stable_diffusion) | [**Stable Diffusion**](https://stability.ai/blog/stable-diffusion-public-release) | Text-Guided Image Inpainting | [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/huggingface/notebooks/blob/main/diffusers/in_painting_with_stable_diffusion_using_diffusers.ipynb)
-| [stochastic_karras_ve](./stochastic_karras_ve) | [**Elucidating the Design Space of Diffusion-Based Generative Models**](https://arxiv.org/abs/2206.00364) | Unconditional Image Generation | 
-| [vq_diffusion](./vq_diffusion) | [**Vector Quantized Diffusion Model for Text-to-Image Synthesis**](https://arxiv.org/abs/2111.14822) | Text-to-Image Generation |
-| [repaint](./repaint)                                 | [**RePaint: Inpainting using Denoising Diffusion Probabilistic Models**](https://arxiv.org/abs/2201.09865)                   |           Image Inpainting            | 
+| [cycle_diffusion](./api/pipelines/cycle_diffusion) | [**Cycle Diffusion**](https://arxiv.org/abs/2210.05559) | Image-to-Image Text-Guided Generation |
+| [dance_diffusion](./api/pipelines/dance_diffusion) | [**Dance Diffusion**](https://github.com/williamberman/diffusers.git) | Unconditional Audio Generation |
+| [ddpm](./api/pipelines/ddpm) | [**Denoising Diffusion Probabilistic Models**](https://arxiv.org/abs/2006.11239) | Unconditional Image Generation |
+| [ddim](./api/pipelines/ddim) | [**Denoising Diffusion Implicit Models**](https://arxiv.org/abs/2010.02502) | Unconditional Image Generation |
+| [latent_diffusion](./api/pipelines/latent_diffusion) | [**High-Resolution Image Synthesis with Latent Diffusion Models**](https://arxiv.org/abs/2112.10752)| Text-to-Image Generation | 
+| [latent_diffusion_uncond](./api/pipelines/latent_diffusion_uncond) | [**High-Resolution Image Synthesis with Latent Diffusion Models**](https://arxiv.org/abs/2112.10752) | Unconditional Image Generation | 
+| [pndm](./api/pipelines/pndm) | [**Pseudo Numerical Methods for Diffusion Models on Manifolds**](https://arxiv.org/abs/2202.09778) | Unconditional Image Generation | 
+| [score_sde_ve](./api/pipelines/score_sde_ve) | [**Score-Based Generative Modeling through Stochastic Differential Equations**](https://openreview.net/forum?id=PxTIG12RRHS) | Unconditional Image Generation | 
+| [score_sde_vp](./api/pipelines/score_sde_vp) | [**Score-Based Generative Modeling through Stochastic Differential Equations**](https://openreview.net/forum?id=PxTIG12RRHS) | Unconditional Image Generation | 
+| [stable_diffusion](./api/pipelines/stable_diffusion) | [**Stable Diffusion**](https://stability.ai/blog/stable-diffusion-public-release) | Text-to-Image Generation | [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/huggingface/notebooks/blob/main/diffusers/training_example.ipynb)
+| [stable_diffusion](./api/pipelines/stable_diffusion) | [**Stable Diffusion**](https://stability.ai/blog/stable-diffusion-public-release) | Image-to-Image Text-Guided Generation | [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/huggingface/notebooks/blob/main/diffusers/image_2_image_using_diffusers.ipynb)
+| [stable_diffusion](./api/pipelines/stable_diffusion) | [**Stable Diffusion**](https://stability.ai/blog/stable-diffusion-public-release) | Text-Guided Image Inpainting | [![Open In Colab](https://colab.research.google.com/assets/colab-badge.svg)](https://colab.research.google.com/github/huggingface/notebooks/blob/main/diffusers/in_painting_with_stable_diffusion_using_diffusers.ipynb)
+| [stochastic_karras_ve](./api/pipelines/stochastic_karras_ve) | [**Elucidating the Design Space of Diffusion-Based Generative Models**](https://arxiv.org/abs/2206.00364) | Unconditional Image Generation | 
+| [vq_diffusion](./api/pipelines/vq_diffusion) | [Vector Quantized Diffusion Model for Text-to-Image Synthesis](https://arxiv.org/abs/2111.14822) | Text-to-Image Generation | 
+
 
 **Note**: Pipelines are simple examples of how to play around with the diffusion systems as described in the corresponding papers. 
 

docs/source/index.mdx

@@ -34,6 +34,7 @@ available a colab notebook to directly try them out.
 
 | Pipeline | Paper | Tasks | Colab
 |---|---|:---:|:---:|
+| [cycle_diffusion](./api/pipelines/cycle_diffusion) | [**Cycle Diffusion**](https://arxiv.org/abs/2210.05559) | Image-to-Image Text-Guided Generation |
 | [dance_diffusion](./api/pipelines/dance_diffusion) | [**Dance Diffusion**](https://github.com/williamberman/diffusers.git) | Unconditional Audio Generation |
 | [ddpm](./api/pipelines/ddpm) | [**Denoising Diffusion Probabilistic Models**](https://arxiv.org/abs/2006.11239) | Unconditional Image Generation |
 | [ddim](./api/pipelines/ddim) | [**Denoising Diffusion Implicit Models**](https://arxiv.org/abs/2010.02502) | Unconditional Image Generation |

src/diffusers/__init__.py

@@ -63,6 +63,7 @@ else:
 
 if is_torch_available() and is_transformers_available():
     from .pipelines import (
+        CycleDiffusionPipeline,
         LDMTextToImagePipeline,
         StableDiffusionImg2ImgPipeline,
         StableDiffusionInpaintPipeline,

src/diffusers/pipelines/__init__.py

@@ -16,6 +16,7 @@ else:
 if is_torch_available() and is_transformers_available():
     from .latent_diffusion import LDMTextToImagePipeline
     from .stable_diffusion import (
+        CycleDiffusionPipeline,
         StableDiffusionImg2ImgPipeline,
         StableDiffusionInpaintPipeline,
         StableDiffusionInpaintPipelineLegacy,

src/diffusers/pipelines/stable_diffusion/README.md

@@ -103,3 +103,74 @@ image = pipe(prompt).sample[0]
     
 image.save("astronaut_rides_horse.png")
 ```
+
+### CycleDiffusion using Stable Diffusion and DDIM scheduler
+
+```python
+import requests
+import torch
+from PIL import Image
+from io import BytesIO
+
+from diffusers import CycleDiffusionPipeline, DDIMScheduler
+
+
+# load the scheduler. CycleDiffusion only supports stochastic schedulers.
+
+# load the pipeline
+# make sure you're logged in with `huggingface-cli login`
+model_id_or_path = "CompVis/stable-diffusion-v1-4"
+scheduler = DDIMScheduler.from_config(model_id_or_path, subfolder="scheduler")
+pipe = CycleDiffusionPipeline.from_pretrained(model_id_or_path, scheduler=scheduler).to("cuda")
+
+# let's download an initial image
+url = "https://raw.githubusercontent.com/ChenWu98/cycle-diffusion/main/data/dalle2/An%20astronaut%20riding%20a%20horse.png"
+response = requests.get(url)
+init_image = Image.open(BytesIO(response.content)).convert("RGB")
+init_image = init_image.resize((512, 512))
+init_image.save("horse.png")
+
+# let's specify a prompt
+source_prompt = "An astronaut riding a horse"
+prompt = "An astronaut riding an elephant"
+
+# call the pipeline
+image = pipe(
+    prompt=prompt,
+    source_prompt=source_prompt,
+    init_image=init_image,
+    num_inference_steps=100,
+    eta=0.1,
+    strength=0.8,
+    guidance_scale=2,
+    source_guidance_scale=1,
+).images[0]
+
+image.save("horse_to_elephant.png")
+
+# let's try another example
+# See more samples at the original repo: https://github.com/ChenWu98/cycle-diffusion
+url = "https://raw.githubusercontent.com/ChenWu98/cycle-diffusion/main/data/dalle2/A%20black%20colored%20car.png"
+response = requests.get(url)
+init_image = Image.open(BytesIO(response.content)).convert("RGB")
+init_image = init_image.resize((512, 512))
+init_image.save("black.png")
+
+source_prompt = "A black colored car"
+prompt = "A blue colored car"
+
+# call the pipeline
+torch.manual_seed(0)
+image = pipe(
+    prompt=prompt,
+    source_prompt=source_prompt,
+    init_image=init_image,
+    num_inference_steps=100,
+    eta=0.1,
+    strength=0.85,
+    guidance_scale=3,
+    source_guidance_scale=1,
+).images[0]
+
+image.save("black_to_blue.png")
+```

src/diffusers/pipelines/stable_diffusion/__init__.py

@@ -28,6 +28,7 @@ class StableDiffusionPipelineOutput(BaseOutput):
 
 
 if is_transformers_available() and is_torch_available():
+    from .pipeline_cycle_diffusion import CycleDiffusionPipeline
     from .pipeline_stable_diffusion import StableDiffusionPipeline
     from .pipeline_stable_diffusion_img2img import StableDiffusionImg2ImgPipeline
     from .pipeline_stable_diffusion_inpaint import StableDiffusionInpaintPipeline

src/diffusers/schedulers/scheduling_ddim.py

@@ -208,6 +208,7 @@ class DDIMScheduler(SchedulerMixin, ConfigMixin):
         eta: float = 0.0,
         use_clipped_model_output: bool = False,
         generator=None,
+        variance_noise: Optional[torch.FloatTensor] = None,
         return_dict: bool = True,
     ) -> Union[DDIMSchedulerOutput, Tuple]:
         """
@@ -225,6 +226,9 @@ class DDIMScheduler(SchedulerMixin, ConfigMixin):
                 `self.config.clip_sample` is `True`. If no clipping has happened, "corrected" `model_output` would
                 coincide with the one provided as input and `use_clipped_model_output` will have not effect.
             generator: random number generator.
+            variance_noise (`torch.FloatTensor`): instead of generating noise for the variance using `generator`, we
+                can directly provide the noise for the variance itself. This is useful for methods such as
+                CycleDiffusion. (https://arxiv.org/abs/2210.05559)
             return_dict (`bool`): option for returning tuple rather than DDIMSchedulerOutput class
 
         Returns:
@@ -284,8 +288,17 @@ class DDIMScheduler(SchedulerMixin, ConfigMixin):
         if eta > 0:
             # randn_like does not support generator https://github.com/pytorch/pytorch/issues/27072
             device = model_output.device if torch.is_tensor(model_output) else "cpu"
-            noise = torch.randn(model_output.shape, dtype=model_output.dtype, generator=generator).to(device)
-            variance = self._get_variance(timestep, prev_timestep) ** (0.5) * eta * noise
+            if variance_noise is not None and generator is not None:
+                raise ValueError(
+                    "Cannot pass both generator and variance_noise. Please make sure that either `generator` or"
+                    " `variance_noise` stays `None`."
+                )
+
+            if variance_noise is None:
+                variance_noise = torch.randn(model_output.shape, dtype=model_output.dtype, generator=generator).to(
+                    device
+                )
+            variance = self._get_variance(timestep, prev_timestep) ** (0.5) * eta * variance_noise
 
             prev_sample = prev_sample + variance
 

src/diffusers/utils/dummy_torch_and_transformers_objects.py

@@ -4,6 +4,21 @@
 from ..utils import DummyObject, requires_backends
 
 
+class CycleDiffusionPipeline(metaclass=DummyObject):
+    _backends = ["torch", "transformers"]
+
+    def __init__(self, *args, **kwargs):
+        requires_backends(self, ["torch", "transformers"])
+
+    @classmethod
+    def from_config(cls, *args, **kwargs):
+        requires_backends(cls, ["torch", "transformers"])
+
+    @classmethod
+    def from_pretrained(cls, *args, **kwargs):
+        requires_backends(cls, ["torch", "transformers"])
+
+
 class LDMTextToImagePipeline(metaclass=DummyObject):
     _backends = ["torch", "transformers"]
 

tests/pipelines/stable_diffusion/test_cycle_diffusion.py

+# coding=utf-8
+# Copyright 2022 HuggingFace Inc.
+#
+# 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 gc
+import random
+import unittest
+
+import numpy as np
+import torch
+
+from diffusers import AutoencoderKL, CycleDiffusionPipeline, DDIMScheduler, UNet2DConditionModel, UNet2DModel, VQModel
+from diffusers.utils import floats_tensor, load_image, load_numpy, slow, torch_device
+from diffusers.utils.testing_utils import require_torch_gpu
+from transformers import CLIPTextConfig, CLIPTextModel, CLIPTokenizer
+
+from ...test_pipelines_common import PipelineTesterMixin
+
+
+torch.backends.cuda.matmul.allow_tf32 = False
+
+
+class CycleDiffusionPipelineFastTests(PipelineTesterMixin, unittest.TestCase):
+    def tearDown(self):
+        # clean up the VRAM after each test
+        super().tearDown()
+        gc.collect()
+        torch.cuda.empty_cache()
+
+    @property
+    def dummy_image(self):
+        batch_size = 1
+        num_channels = 3
+        sizes = (32, 32)
+
+        image = floats_tensor((batch_size, num_channels) + sizes, rng=random.Random(0)).to(torch_device)
+        return image
+
+    @property
+    def dummy_uncond_unet(self):
+        torch.manual_seed(0)
+        model = UNet2DModel(
+            block_out_channels=(32, 64),
+            layers_per_block=2,
+            sample_size=32,
+            in_channels=3,
+            out_channels=3,
+            down_block_types=("DownBlock2D", "AttnDownBlock2D"),
+            up_block_types=("AttnUpBlock2D", "UpBlock2D"),
+        )
+        return model
+
+    @property
+    def dummy_cond_unet(self):
+        torch.manual_seed(0)
+        model = UNet2DConditionModel(
+            block_out_channels=(32, 64),
+            layers_per_block=2,
+            sample_size=32,
+            in_channels=4,
+            out_channels=4,
+            down_block_types=("DownBlock2D", "CrossAttnDownBlock2D"),
+            up_block_types=("CrossAttnUpBlock2D", "UpBlock2D"),
+            cross_attention_dim=32,
+        )
+        return model
+
+    @property
+    def dummy_cond_unet_inpaint(self):
+        torch.manual_seed(0)
+        model = UNet2DConditionModel(
+            block_out_channels=(32, 64),
+            layers_per_block=2,
+            sample_size=32,
+            in_channels=9,
+            out_channels=4,
+            down_block_types=("DownBlock2D", "CrossAttnDownBlock2D"),
+            up_block_types=("CrossAttnUpBlock2D", "UpBlock2D"),
+            cross_attention_dim=32,
+        )
+        return model
+
+    @property
+    def dummy_vq_model(self):
+        torch.manual_seed(0)
+        model = VQModel(
+            block_out_channels=[32, 64],
+            in_channels=3,
+            out_channels=3,
+            down_block_types=["DownEncoderBlock2D", "DownEncoderBlock2D"],
+            up_block_types=["UpDecoderBlock2D", "UpDecoderBlock2D"],
+            latent_channels=3,
+        )
+        return model
+
+    @property
+    def dummy_vae(self):
+        torch.manual_seed(0)
+        model = AutoencoderKL(
+            block_out_channels=[32, 64],
+            in_channels=3,
+            out_channels=3,
+            down_block_types=["DownEncoderBlock2D", "DownEncoderBlock2D"],
+            up_block_types=["UpDecoderBlock2D", "UpDecoderBlock2D"],
+            latent_channels=4,
+        )
+        return model
+
+    @property
+    def dummy_text_encoder(self):
+        torch.manual_seed(0)
+        config = CLIPTextConfig(
+            bos_token_id=0,
+            eos_token_id=2,
+            hidden_size=32,
+            intermediate_size=37,
+            layer_norm_eps=1e-05,
+            num_attention_heads=4,
+            num_hidden_layers=5,
+            pad_token_id=1,
+            vocab_size=1000,
+        )
+        return CLIPTextModel(config)
+
+    @property
+    def dummy_extractor(self):
+        def extract(*args, **kwargs):
+            class Out:
+                def __init__(self):
+                    self.pixel_values = torch.ones([0])
+
+                def to(self, device):
+                    self.pixel_values.to(device)
+                    return self
+
+            return Out()
+
+        return extract
+
+    def test_stable_diffusion_cycle(self):
+        device = "cpu"  # ensure determinism for the device-dependent torch.Generator
+        unet = self.dummy_cond_unet
+        scheduler = DDIMScheduler(
+            beta_start=0.00085,
+            beta_end=0.012,
+            beta_schedule="scaled_linear",
+            num_train_timesteps=1000,
+            clip_sample=False,
+            set_alpha_to_one=False,
+        )
+        vae = self.dummy_vae
+        bert = self.dummy_text_encoder
+        tokenizer = CLIPTokenizer.from_pretrained("hf-internal-testing/tiny-random-clip")
+
+        # make sure here that pndm scheduler skips prk
+        sd_pipe = CycleDiffusionPipeline(
+            unet=unet,
+            scheduler=scheduler,
+            vae=vae,
+            text_encoder=bert,
+            tokenizer=tokenizer,
+            safety_checker=None,
+            feature_extractor=self.dummy_extractor,
+        )
+        sd_pipe = sd_pipe.to(device)
+        sd_pipe.set_progress_bar_config(disable=None)
+
+        source_prompt = "An astronaut riding a horse"
+        prompt = "An astronaut riding an elephant"
+        init_image = self.dummy_image.to(device)
+
+        generator = torch.Generator(device=device).manual_seed(0)
+        output = sd_pipe(
+            prompt=prompt,
+            source_prompt=source_prompt,
+            generator=generator,
+            num_inference_steps=2,
+            init_image=init_image,
+            eta=0.1,
+            strength=0.8,
+            guidance_scale=3,
+            source_guidance_scale=1,
+            output_type="np",
+        )
+        images = output.images
+
+        image_slice = images[0, -3:, -3:, -1]
+
+        assert images.shape == (1, 32, 32, 3)
+        expected_slice = np.array([0.4459, 0.4943, 0.4544, 0.6643, 0.5474, 0.4327, 0.5701, 0.5959, 0.5179])
+
+        assert np.abs(image_slice.flatten() - expected_slice).max() < 1e-2
+
+    @unittest.skipIf(torch_device != "cuda", "This test requires a GPU")
+    def test_stable_diffusion_cycle_fp16(self):
+        unet = self.dummy_cond_unet
+        scheduler = DDIMScheduler(
+            beta_start=0.00085,
+            beta_end=0.012,
+            beta_schedule="scaled_linear",
+            num_train_timesteps=1000,
+            clip_sample=False,
+            set_alpha_to_one=False,
+        )
+        vae = self.dummy_vae
+        bert = self.dummy_text_encoder
+        tokenizer = CLIPTokenizer.from_pretrained("hf-internal-testing/tiny-random-clip")
+
+        unet = unet.half()
+        vae = vae.half()
+        bert = bert.half()
+
+        # make sure here that pndm scheduler skips prk
+        sd_pipe = CycleDiffusionPipeline(
+            unet=unet,
+            scheduler=scheduler,
+            vae=vae,
+            text_encoder=bert,
+            tokenizer=tokenizer,
+            safety_checker=None,
+            feature_extractor=self.dummy_extractor,
+        )
+        sd_pipe = sd_pipe.to(torch_device)
+        sd_pipe.set_progress_bar_config(disable=None)
+
+        source_prompt = "An astronaut riding a horse"
+        prompt = "An astronaut riding an elephant"
+        init_image = self.dummy_image.to(torch_device)
+
+        generator = torch.Generator(device=torch_device).manual_seed(0)
+        output = sd_pipe(
+            prompt=prompt,
+            source_prompt=source_prompt,
+            generator=generator,
+            num_inference_steps=2,
+            init_image=init_image,
+            eta=0.1,
+            strength=0.8,
+            guidance_scale=3,
+            source_guidance_scale=1,
+            output_type="np",
+        )
+        images = output.images
+
+        image_slice = images[0, -3:, -3:, -1]
+
+        assert images.shape == (1, 32, 32, 3)
+        expected_slice = np.array([0.3506, 0.4543, 0.446, 0.4575, 0.5195, 0.4155, 0.5273, 0.518, 0.4116])
+
+        assert np.abs(image_slice.flatten() - expected_slice).max() < 1e-2
+
+
+@slow
+@require_torch_gpu
+class CycleDiffusionPipelineIntegrationTests(unittest.TestCase):
+    def tearDown(self):
+        # clean up the VRAM after each test
+        super().tearDown()
+        gc.collect()
+        torch.cuda.empty_cache()
+
+    def test_cycle_diffusion_pipeline_fp16(self):
+        init_image = load_image(
+            "https://huggingface.co/datasets/hf-internal-testing/diffusers-images/resolve/main"
+            "/cycle-diffusion/black_colored_car.png"
+        )
+        expected_image = load_numpy(
+            "https://huggingface.co/datasets/hf-internal-testing/diffusers-images/resolve/main/cycle-diffusion/blue_colored_car_fp16.npy"
+        )
+        init_image = init_image.resize((512, 512))
+
+        model_id = "CompVis/stable-diffusion-v1-4"
+        scheduler = DDIMScheduler.from_config(model_id, subfolder="scheduler")
+        pipe = CycleDiffusionPipeline.from_pretrained(
+            model_id, scheduler=scheduler, safety_checker=None, torch_dtype=torch.float16, revision="fp16"
+        )
+
+        pipe.to(torch_device)
+        pipe.set_progress_bar_config(disable=None)
+        pipe.enable_attention_slicing()
+
+        source_prompt = "A black colored car"
+        prompt = "A blue colored car"
+
+        torch.manual_seed(0)
+        output = pipe(
+            prompt=prompt,
+            source_prompt=source_prompt,
+            init_image=init_image,
+            num_inference_steps=100,
+            eta=0.1,
+            strength=0.85,
+            guidance_scale=3,
+            source_guidance_scale=1,
+            output_type="np",
+        )
+        image = output.images
+
+        # the values aren't exactly equal, but the images look the same visually
+        assert np.abs(image - expected_image).max() < 1e-2
+
+    def test_cycle_diffusion_pipeline(self):
+        init_image = load_image(
+            "https://huggingface.co/datasets/hf-internal-testing/diffusers-images/resolve/main"
+            "/cycle-diffusion/black_colored_car.png"
+        )
+        expected_image = load_numpy(
+            "https://huggingface.co/datasets/hf-internal-testing/diffusers-images/resolve/main/cycle-diffusion/blue_colored_car.npy"
+        )
+        init_image = init_image.resize((512, 512))
+
+        model_id = "CompVis/stable-diffusion-v1-4"
+        scheduler = DDIMScheduler.from_config(model_id, subfolder="scheduler")
+        pipe = CycleDiffusionPipeline.from_pretrained(model_id, scheduler=scheduler, safety_checker=None)
+
+        pipe.to(torch_device)
+        pipe.set_progress_bar_config(disable=None)
+        pipe.enable_attention_slicing()
+
+        source_prompt = "A black colored car"
+        prompt = "A blue colored car"
+
+        torch.manual_seed(0)
+        output = pipe(
+            prompt=prompt,
+            source_prompt=source_prompt,
+            init_image=init_image,
+            num_inference_steps=100,
+            eta=0.1,
+            strength=0.85,
+            guidance_scale=3,
+            source_guidance_scale=1,
+            output_type="np",
+        )
+        image = output.images
+
+        assert np.abs(image - expected_image).max() < 1e-2