from typing import Callable, List, Optional, Union, Any, Dict import copy import numpy as np import PIL import torch from diffusers import StableDiffusionPipeline, DDIMScheduler, UNet2DConditionModel from diffusers.utils import logging, BaseOutput from torchvision.transforms import ToPILImage logger = logging.get_logger(__name__) # pylint: disable=invalid-name class ModifiedStableDiffusionPipelineOutput(BaseOutput): images: Union[List[PIL.Image.Image], np.ndarray] nsfw_content_detected: Optional[List[bool]] init_latents: Optional[torch.FloatTensor] class ModifiedStableDiffusionPipeline(StableDiffusionPipeline): def __init__(self, vae, text_encoder, tokenizer, unet, scheduler, safety_checker, feature_extractor, requires_safety_checker: bool = False, ): super(ModifiedStableDiffusionPipeline, self).__init__(vae, text_encoder, tokenizer, unet, scheduler, safety_checker, feature_extractor, requires_safety_checker) @torch.no_grad() def __call__( self, prompt: Union[str, List[str]], height: Optional[int] = None, width: Optional[int] = None, num_inference_steps: int = 50, guidance_scale: float = 7.5, negative_prompt: Optional[Union[str, List[str]]] = None, num_images_per_prompt: Optional[int] = 1, eta: float = 0.0, generator: Optional[Union[torch.Generator, List[torch.Generator]]] = None, latents: Optional[torch.FloatTensor] = None, output_type: Optional[str] = "pil", return_dict: bool = True, callback: Optional[Callable[[int, int, torch.FloatTensor], None]] = None, callback_steps: Optional[int] = 1, watermarking_gamma: float = None, watermarking_delta: float = None, watermarking_mask: Optional[torch.BoolTensor] = None, ): r""" Function invoked when calling the pipeline for generation. Args: prompt (`str` or `List[str]`): The prompt or prompts to guide the image generation. 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](https://arxiv.org/abs/2207.12598). `guidance_scale` is defined as `w` of equation 2. of [Imagen Paper](https://arxiv.org/pdf/2205.11487.pdf). 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. 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`, *optional*): One or a list of [torch generator(s)](https://pytorch.org/docs/stable/generated/torch.Generator.html) 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`. output_type (`str`, *optional*, defaults to `"pil"`): The output format of the generate image. Choose between [PIL](https://pillow.readthedocs.io/en/stable/): `PIL.Image.Image` or `np.array`. return_dict (`bool`, *optional*, defaults to `True`): Whether or not to return a [`~pipelines.stable_diffusion.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. Returns: [`~pipelines.stable_diffusion.StableDiffusionPipelineOutput`] or `tuple`: [`~pipelines.stable_diffusion.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 `bool`s denoting whether the corresponding generated image likely represents "not-safe-for-work" (nsfw) content, according to the `safety_checker`. """ # 0. Default height and width to unet height = height or self.unet.config.sample_size * self.vae_scale_factor width = width or self.unet.config.sample_size * self.vae_scale_factor self.count = 0 # 1. Check inputs. Raise error if not correct self.check_inputs(prompt, height, width, callback_steps) # 2. Define call parameters batch_size = 1 if isinstance(prompt, str) else len(prompt) device = self._execution_device # here `guidance_scale` is defined analog to the guidance weight `w` of equation (2) # of the Imagen paper: https://arxiv.org/pdf/2205.11487.pdf . `guidance_scale = 1` # corresponds to doing no classifier free guidance. do_classifier_free_guidance = guidance_scale > 1.0 # 3. Encode input prompt text_embeddings = self._encode_prompt( prompt, device, num_images_per_prompt, do_classifier_free_guidance, negative_prompt ) # 4. Prepare timesteps self.scheduler.set_timesteps(num_inference_steps, device=device) timesteps = self.scheduler.timesteps # 5. Prepare latent variables num_channels_latents = self.unet.in_channels latents = self.prepare_latents( batch_size * num_images_per_prompt, num_channels_latents, height, width, text_embeddings.dtype, device, generator, latents, ) init_latents = copy.deepcopy(latents) # watermarking mask if watermarking_gamma is not None: watermarking_mask = torch.rand(latents.shape, device=device) < watermarking_gamma # 6. Prepare extra step kwargs. TODO: Logic should ideally just be moved out of the pipeline extra_step_kwargs = self.prepare_extra_step_kwargs(generator, eta) # 7. Denoising loop num_warmup_steps = len(timesteps) - num_inference_steps * self.scheduler.order with self.progress_bar(total=num_inference_steps) as progress_bar: for i, t in enumerate(timesteps): # add watermark if watermarking_mask is not None: # latents[watermarking_mask] += watermarking_delta latents[watermarking_mask] += watermarking_delta * torch.sign(latents[watermarking_mask]) # expand the latents if we are doing classifier free guidance latent_model_input = torch.cat([latents] * 2) if do_classifier_free_guidance else latents latent_model_input = self.scheduler.scale_model_input(latent_model_input, t) # predict the noise residual noise_pred = self.unet(latent_model_input, t, encoder_hidden_states=text_embeddings).sample # perform guidance if do_classifier_free_guidance: noise_pred_uncond, noise_pred_text = noise_pred.chunk(2) noise_pred = noise_pred_uncond + guidance_scale * (noise_pred_text - noise_pred_uncond) # compute the previous noisy sample x_t -> x_t-1 latents = self.scheduler.step(noise_pred, t, latents, **extra_step_kwargs).prev_sample # call the callback, if provided if i == len(timesteps) - 1 or ((i + 1) > num_warmup_steps and (i + 1) % self.scheduler.order == 0): progress_bar.update() if callback is not None and i % callback_steps == 0: callback(i, t, latents) # 8. Post-processing image = self.decode_latents(latents) # 9. Run safety checker image, has_nsfw_concept = self.run_safety_checker(image, device, text_embeddings.dtype) # 10. Convert to PIL if output_type == "pil": image = self.numpy_to_pil(image) if not return_dict: return (image, has_nsfw_concept) return ModifiedStableDiffusionPipelineOutput(images=image, nsfw_content_detected=has_nsfw_concept, init_latents=init_latents) @torch.inference_mode() def decode_image(self, latents: torch.FloatTensor, **kwargs): scaled_latents = 1 / 0.18215 * latents image = [ self.vae.decode(scaled_latents[i : i + 1]).sample for i in range(len(latents)) ] image = torch.cat(image, dim=0) return image @torch.inference_mode() def torch_to_numpy(self, image): image = (image / 2 + 0.5).clamp(0, 1) image = image.cpu().permute(0, 2, 3, 1).numpy() return image @torch.inference_mode() def get_image_latents(self, image, sample=True, rng_generator=None): encoding_dist = self.vae.encode(image).latent_dist if sample: encoding = encoding_dist.sample(generator=rng_generator) else: encoding = encoding_dist.mode() latents = encoding * 0.18215 return latents