import argparse import torch from baukit import TraceDict from diffusers import AutoencoderKL, UNet2DConditionModel from PIL import Image from tqdm.auto import tqdm from transformers import CLIPTextModel, CLIPTokenizer from diffusers.schedulers.scheduling_ddim import DDIMScheduler from diffusers.schedulers.scheduling_ddpm import DDPMScheduler from diffusers.schedulers.scheduling_lms_discrete import LMSDiscreteScheduler import util def default_parser(): parser = argparse.ArgumentParser() parser.add_argument('prompts', type=str, nargs='+') parser.add_argument('outpath', type=str) parser.add_argument('--images', type=str, nargs='+', default=None) parser.add_argument('--nsteps', type=int, default=1000) parser.add_argument('--nimgs', type=int, default=1) parser.add_argument('--start_itr', type=int, default=0) parser.add_argument('--return_steps', action='store_true', default=False) parser.add_argument('--pred_x0', action='store_true', default=False) parser.add_argument('--device', type=str, default='cuda:0') parser.add_argument('--seed', type=int, default=42) return parser class StableDiffuser(torch.nn.Module): def __init__(self, scheduler='LMS' ): super().__init__() # Load the autoencoder model which will be used to decode the latents into image space. self.vae = AutoencoderKL.from_pretrained( "CompVis/stable-diffusion-v1-4", subfolder="vae") # Load the tokenizer and text encoder to tokenize and encode the text. self.tokenizer = CLIPTokenizer.from_pretrained( "openai/clip-vit-large-patch14") self.text_encoder = CLIPTextModel.from_pretrained( "openai/clip-vit-large-patch14") # The UNet model for generating the latents. self.unet = UNet2DConditionModel.from_pretrained( "CompVis/stable-diffusion-v1-4", subfolder="unet") if scheduler == 'LMS': self.scheduler = LMSDiscreteScheduler(beta_start=0.00085, beta_end=0.012, beta_schedule="scaled_linear", num_train_timesteps=1000) elif scheduler == 'DDIM': self.scheduler = DDIMScheduler.from_pretrained("CompVis/stable-diffusion-v1-4", subfolder="scheduler") elif scheduler == 'DDPM': self.scheduler = DDPMScheduler.from_pretrained("CompVis/stable-diffusion-v1-4", subfolder="scheduler") self.eval() def get_noise(self, batch_size, img_size, generator=None): param = list(self.parameters())[0] return torch.randn( (batch_size, self.unet.in_channels, img_size // 8, img_size // 8), generator=generator).type(param.dtype).to(param.device) def add_noise(self, latents, noise, step): return self.scheduler.add_noise(latents, noise, torch.tensor([self.scheduler.timesteps[step]])) def text_tokenize(self, prompts): return self.tokenizer(prompts, padding="max_length", max_length=self.tokenizer.model_max_length, truncation=True, return_tensors="pt") def text_detokenize(self, tokens): return [self.tokenizer.decode(token) for token in tokens if token != self.tokenizer.vocab_size - 1] def text_encode(self, tokens): return self.text_encoder(tokens.input_ids.to(self.unet.device))[0] def decode(self, latents): return self.vae.decode(1 / self.vae.config.scaling_factor * latents).sample def encode(self, tensors): return self.vae.encode(tensors).latent_dist.mode() * 0.18215 def to_image(self, image): image = (image / 2 + 0.5).clamp(0, 1) image = image.detach().cpu().permute(0, 2, 3, 1).numpy() images = (image * 255).round().astype("uint8") pil_images = [Image.fromarray(image) for image in images] return pil_images def set_scheduler_timesteps(self, n_steps): self.scheduler.set_timesteps(n_steps, device=self.unet.device) def get_initial_latents(self, n_imgs, img_size, n_prompts, generator=None): noise = self.get_noise(n_imgs, img_size, generator=generator).repeat(n_prompts, 1, 1, 1) latents = noise * self.scheduler.init_noise_sigma return latents def get_text_embeddings(self, prompts, n_imgs): text_tokens = self.text_tokenize(prompts) text_embeddings = self.text_encode(text_tokens) unconditional_tokens = self.text_tokenize([""] * len(prompts)) unconditional_embeddings = self.text_encode(unconditional_tokens) text_embeddings = torch.cat([unconditional_embeddings, text_embeddings]).repeat_interleave(n_imgs, dim=0) return text_embeddings def predict_noise(self, iteration, latents, text_embeddings, guidance_scale=7.5 ): # expand the latents if we are doing classifier-free guidance to avoid doing two forward passes. latents = torch.cat([latents] * 2) latents = self.scheduler.scale_model_input( latents, self.scheduler.timesteps[iteration]) # predict the noise residual noise_prediction = self.unet( latents, self.scheduler.timesteps[iteration], encoder_hidden_states=text_embeddings).sample # perform guidance noise_prediction_uncond, noise_prediction_text = noise_prediction.chunk(2) noise_prediction = noise_prediction_uncond + guidance_scale * \ (noise_prediction_text - noise_prediction_uncond) return noise_prediction @torch.no_grad() def diffusion(self, latents, text_embeddings, end_iteration=1000, start_iteration=0, return_steps=False, pred_x0=False, trace_args=None, show_progress=True, **kwargs): latents_steps = [] trace_steps = [] trace = None for iteration in tqdm(range(start_iteration, end_iteration), disable=not show_progress): if trace_args: trace = TraceDict(self, **trace_args) noise_pred = self.predict_noise( iteration, latents, text_embeddings, **kwargs) # compute the previous noisy sample x_t -> x_t-1 output = self.scheduler.step(noise_pred, self.scheduler.timesteps[iteration], latents) if trace_args: trace.close() trace_steps.append(trace) latents = output.prev_sample if return_steps or iteration == end_iteration - 1: output = output.pred_original_sample if pred_x0 else latents if return_steps: latents_steps.append(output.cpu()) else: latents_steps.append(output) return latents_steps, trace_steps @torch.no_grad() def __call__(self, prompts, img_size=512, n_steps=50, n_imgs=1, end_iteration=None, generator=None, **kwargs ): assert 0 <= n_steps <= 1000 if not isinstance(prompts, list): prompts = [prompts] self.set_scheduler_timesteps(n_steps) latents = self.get_initial_latents(n_imgs, img_size, len(prompts), generator=generator) text_embeddings = self.get_text_embeddings(prompts,n_imgs=n_imgs) end_iteration = end_iteration or n_steps latents_steps, trace_steps = self.diffusion( latents, text_embeddings, end_iteration=end_iteration, **kwargs ) latents_steps = [self.decode(latents.to(self.unet.device)) for latents in latents_steps] images_steps = [self.to_image(latents) for latents in latents_steps] images_steps = list(zip(*images_steps)) if trace_steps: return images_steps, trace_steps return images_steps if __name__ == '__main__': parser = default_parser() args = parser.parse_args() diffuser = StableDiffuser(seed=args.seed, scheduler='DDIM').to(torch.device(args.device)).half() images = diffuser(args.prompts, n_steps=args.nsteps, n_imgs=args.nimgs, start_iteration=args.start_itr, return_steps=args.return_steps, pred_x0=args.pred_x0 ) util.image_grid(images, args.outpath)