Zero-shot Image-to-Image Translation

Overview

Zero-shot Image-to-Image Translation by Gaurav Parmar, Krishna Kumar Singh, Richard Zhang, Yijun Li, Jingwan Lu, and Jun-Yan Zhu.

The abstract of the paper is the following:

Large-scale text-to-image generative models have shown their remarkable ability to synthesize diverse and high-quality images. However, it is still challenging to directly apply these models for editing real images for two reasons. First, it is hard for users to come up with a perfect text prompt that accurately describes every visual detail in the input image. Second, while existing models can introduce desirable changes in certain regions, they often dramatically alter the input content and introduce unexpected changes in unwanted regions. In this work, we propose pix2pix-zero, an image-to-image translation method that can preserve the content of the original image without manual prompting. We first automatically discover editing directions that reflect desired edits in the text embedding space. To preserve the general content structure after editing, we further propose cross-attention guidance, which aims to retain the cross-attention maps of the input image throughout the diffusion process. In addition, our method does not need additional training for these edits and can directly use the existing pre-trained text-to-image diffusion model. We conduct extensive experiments and show that our method outperforms existing and concurrent works for both real and synthetic image editing.

Resources:

Tips

Available Pipelines:

Pipeline Tasks Demo
StableDiffusionPix2PixZeroPipeline Text-Based Image Editing [🤗 Space] (soon)

Usage example

Based on an image generated with the input prompt

import requests
import torch

from diffusers import DDIMScheduler, StableDiffusionPix2PixZeroPipeline


def download(embedding_url, local_filepath):
    r = requests.get(embedding_url)
    with open(local_filepath, "wb") as f:
        f.write(r.content)


model_ckpt = "CompVis/stable-diffusion-v1-4"
pipeline = StableDiffusionPix2PixZeroPipeline.from_pretrained(
    model_ckpt, conditions_input_image=False, torch_dtype=torch.float16
)
pipeline.scheduler = DDIMScheduler.from_config(pipeline.scheduler.config)
pipeline.to("cuda")

prompt = "a high resolution painting of a cat in the style of van gough"
src_embs_url = "https://github.com/pix2pixzero/pix2pix-zero/raw/main/assets/embeddings_sd_1.4/cat.pt"
target_embs_url = "https://github.com/pix2pixzero/pix2pix-zero/raw/main/assets/embeddings_sd_1.4/dog.pt"

for url in [src_embs_url, target_embs_url]:
    download(url, url.split("/")[-1])

src_embeds = torch.load(src_embs_url.split("/")[-1])
target_embeds = torch.load(target_embs_url.split("/")[-1])

images = pipeline(
    prompt,
    source_embeds=src_embeds,
    target_embeds=target_embeds,
    num_inference_steps=50,
    cross_attention_guidance_amount=0.15,
).images
images[0].save("edited_image_dog.png")

Based on an input image

Coming soon

StableDiffusionPix2PixZeroPipeline

class diffusers.StableDiffusionPix2PixZeroPipeline

< >

( vae: AutoencoderKL text_encoder: CLIPTextModel tokenizer: CLIPTokenizer unet: UNet2DConditionModel scheduler: typing.Union[diffusers.schedulers.scheduling_ddpm.DDPMScheduler, diffusers.schedulers.scheduling_ddim.DDIMScheduler, diffusers.schedulers.scheduling_euler_ancestral_discrete.EulerAncestralDiscreteScheduler, diffusers.schedulers.scheduling_lms_discrete.LMSDiscreteScheduler] safety_checker: StableDiffusionSafetyChecker feature_extractor: CLIPFeatureExtractor conditions_input_image: bool = False requires_safety_checker: bool = True )

Parameters

  • vae (AutoencoderKL) — Variational Auto-Encoder (VAE) Model to encode and decode images to and from latent representations.
  • text_encoder (CLIPTextModel) — Frozen text-encoder. Stable Diffusion uses the text portion of CLIP, specifically the clip-vit-large-patch14 variant.
  • tokenizer (CLIPTokenizer) — Tokenizer of class CLIPTokenizer.
  • unet (UNet2DConditionModel) — Conditional U-Net architecture to denoise the encoded image latents.
  • scheduler (SchedulerMixin) — A scheduler to be used in combination with unet to denoise the encoded image latents. Can be one of DDIMScheduler, LMSDiscreteScheduler, EulerAncestralDiscreteScheduler, or DDPMScheduler.
  • safety_checker (StableDiffusionSafetyChecker) — Classification module that estimates whether generated images could be considered offensive or harmful. Please, refer to the model card for details.
  • feature_extractor (CLIPFeatureExtractor) — Model that extracts features from generated images to be used as inputs for the safety_checker.
  • conditions_input_image (bool) — Whether to condition the pipeline with an input image to compute an inverted noise latent.
  • requires_safety_checker (bool) — Whether the pipeline requires a safety checker. We recommend setting it to True if you’re using the pipeline publicly.

Pipeline for pixel-levl image editing using Pix2Pix Zero. Based on Stable Diffusion.

This model inherits from DiffusionPipeline. Check the superclass documentation for the generic methods the library implements for all the pipelines (such as downloading or saving, running on a particular device, etc.)

__call__

< >

( prompt: typing.Union[str, typing.List[str], NoneType] = None image: typing.Union[torch.FloatTensor, PIL.Image.Image, NoneType] = None source_embeds: Tensor = None target_embeds: Tensor = None height: typing.Optional[int] = None width: typing.Optional[int] = None num_inference_steps: int = 50 guidance_scale: float = 7.5 negative_prompt: typing.Union[str, typing.List[str], NoneType] = None num_images_per_prompt: typing.Optional[int] = 1 eta: float = 0.0 generator: typing.Union[torch._C.Generator, typing.List[torch._C.Generator], NoneType] = None latents: typing.Optional[torch.FloatTensor] = None prompt_embeds: typing.Optional[torch.FloatTensor] = None negative_prompt_embeds: typing.Optional[torch.FloatTensor] = None cross_attention_guidance_amount: float = 0.1 output_type: typing.Optional[str] = 'pil' return_dict: bool = True callback: typing.Union[typing.Callable[[int, int, torch.FloatTensor], NoneType], NoneType] = None callback_steps: typing.Optional[int] = 1 cross_attention_kwargs: typing.Union[typing.Dict[str, typing.Any], NoneType] = None ) StableDiffusionPipelineOutput or tuple

Parameters

  • prompt (str or List[str], optional) — The prompt or prompts to guide the image generation. If not defined, one has to pass prompt_embeds. instead.
  • image (PIL.Image.Image, optional) — Image, or tensor representing an image batch which will be used for conditioning.
  • source_embeds (torch.Tensor) — Source concept embeddings. Generation of the embeddings as per the original paper. Used in discovering the edit direction.
  • target_embeds (torch.Tensor) — Target concept embeddings. Generation of the embeddings as per the original paper. Used in discovering the edit direction.
  • height (int, optional, defaults to self.unet.config.sample_size * self.vae_scale_factor) — The height in pixels of the generated image.
  • width (int, optional, defaults to self.unet.config.sample_size * self.vae_scale_factor) — The width in pixels of the generated image.
  • num_inference_steps (int, optional, defaults to 50) — The number of denoising steps. More denoising steps usually lead to a higher quality image at the expense of slower inference.
  • guidance_scale (float, optional, defaults to 7.5) — Guidance scale as defined in Classifier-Free Diffusion Guidance. guidance_scale is defined as w of equation 2. of Imagen Paper. Guidance scale is enabled by setting guidance_scale > 1. Higher guidance scale encourages to generate images that are closely linked to the text prompt, usually at the expense of lower image quality.
  • negative_prompt (str or List[str], optional) — The prompt or prompts not to guide the image generation. If not defined, one has to pass negative_prompt_embeds. instead. If not defined, one has to pass negative_prompt_embeds. instead. Ignored when not using guidance (i.e., ignored if guidance_scale is less than 1).
  • num_images_per_prompt (int, optional, defaults to 1) — The number of images to generate per prompt.
  • eta (float, optional, defaults to 0.0) — Corresponds to parameter eta (η) in the DDIM paper: https://arxiv.org/abs/2010.02502. Only applies to schedulers.DDIMScheduler, will be ignored for others.
  • generator (torch.Generator or List[torch.Generator], optional) — One or a list of torch generator(s) to make generation deterministic.
  • latents (torch.FloatTensor, optional) — Pre-generated noisy latents, sampled from a Gaussian distribution, to be used as inputs for image generation. Can be used to tweak the same generation with different prompts. If not provided, a latents tensor will ge generated by sampling using the supplied random generator.
  • prompt_embeds (torch.FloatTensor, optional) — Pre-generated text embeddings. Can be used to easily tweak text inputs, e.g. prompt weighting. If not provided, text embeddings will be generated from prompt input argument.
  • negative_prompt_embeds (torch.FloatTensor, optional) — Pre-generated negative text embeddings. Can be used to easily tweak text inputs, e.g. prompt weighting. If not provided, negative_prompt_embeds will be generated from negative_prompt input argument.
  • cross_attention_guidance_amount (float, defaults to 0.1) — Amount of guidance needed from the reference cross-attention maps.
  • output_type (str, optional, defaults to "pil") — The output format of the generate image. Choose between PIL: PIL.Image.Image or np.array.
  • return_dict (bool, optional, defaults to True) — Whether or not to return a StableDiffusionPipelineOutput instead of a plain tuple.
  • callback (Callable, optional) — A function that will be called every callback_steps steps during inference. The function will be called with the following arguments: callback(step: int, timestep: int, latents: torch.FloatTensor).
  • callback_steps (int, optional, defaults to 1) — The frequency at which the callback function will be called. If not specified, the callback will be called at every step.

StableDiffusionPipelineOutput if return_dict is True, otherwise a tuple. When returning a tuple, the first element is a list with the generated images, and the second element is a list of bools denoting whether the corresponding generated image likely represents "not-safe-for-work" (nsfw) content, according to the safety_checker`.

Function invoked when calling the pipeline for generation.

Examples:

>>> import requests
>>> import torch

>>> from diffusers import DDIMScheduler, StableDiffusionPix2PixZeroPipeline


>>> def download(embedding_url, local_filepath):
...     r = requests.get(embedding_url)
...     with open(local_filepath, "wb") as f:
...         f.write(r.content)


>>> model_ckpt = "CompVis/stable-diffusion-v1-4"
>>> pipeline = StableDiffusionPix2PixZeroPipeline.from_pretrained(
...     model_ckpt, conditions_input_image=False, torch_dtype=torch.float16
... )
>>> pipeline.scheduler = DDIMScheduler.from_config(pipeline.scheduler.config)
>>> pipeline.to("cuda")

>>> prompt = "a high resolution painting of a cat in the style of van gough"
>>> source_emb_url = "https://hf.co/datasets/sayakpaul/sample-datasets/resolve/main/cat.pt"
>>> target_emb_url = "https://hf.co/datasets/sayakpaul/sample-datasets/resolve/main/dog.pt"

>>> for url in [source_emb_url, target_emb_url]:
...     download(url, url.split("/")[-1])

>>> src_embeds = torch.load(source_emb_url.split("/")[-1])
>>> target_embeds = torch.load(target_emb_url.split("/")[-1])
>>> images = pipeline(
...     prompt,
...     source_embeds=src_embeds,
...     target_embeds=target_embeds,
...     num_inference_steps=50,
...     cross_attention_guidance_amount=0.15,
... ).images
>>> images[0].save("edited_image_dog.png")

construct_direction

< >

( embs_source: Tensor embs_target: Tensor )

Constructs the edit direction to steer the image generation process semantically.

enable_sequential_cpu_offload

< >

( gpu_id = 0 )

Offloads all models to CPU using accelerate, significantly reducing memory usage. When called, unet, text_encoder, vae and safety checker have their state dicts saved to CPU and then are moved to a torch.device('meta') and loaded to GPU only when their specific submodule has its forwardmethod called. Note that offloading happens on a submodule basis. Memory savings are higher than withenable_model_cpu_offload`, but performance is lower.

generate_caption

< >

( image return_image = True )

Generates caption for a given image.