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| import logging | |
| import math | |
| from typing import Dict, List, Optional, Tuple | |
| import PIL | |
| import PIL.Image | |
| import torch | |
| from diffusers import DiffusionPipeline | |
| from rewards import clip_img_transform | |
| from rewards.base_reward import BaseRewardLoss | |
| class LatentNoiseTrainer: | |
| """Trainer for optimizing latents with reward losses.""" | |
| def __init__( | |
| self, | |
| reward_losses: List[BaseRewardLoss], | |
| model: DiffusionPipeline, | |
| n_iters: int, | |
| n_inference_steps: int, | |
| seed: int, | |
| no_optim: bool = False, | |
| regularize: bool = True, | |
| regularization_weight: float = 0.01, | |
| grad_clip: float = 0.1, | |
| log_metrics: bool = True, | |
| save_all_images: bool = False, | |
| imageselect: bool = False, | |
| device: torch.device = torch.device("cuda"), | |
| ): | |
| self.reward_losses = reward_losses | |
| self.model = model | |
| self.n_iters = n_iters | |
| self.n_inference_steps = n_inference_steps | |
| self.seed = seed | |
| self.no_optim = no_optim | |
| self.regularize = regularize | |
| self.regularization_weight = regularization_weight | |
| self.grad_clip = grad_clip | |
| self.log_metrics = log_metrics | |
| self.save_all_images = save_all_images | |
| self.imageselect = imageselect | |
| self.device = device | |
| self.preprocess_fn = clip_img_transform(224) | |
| def train( | |
| self, | |
| latents: torch.Tensor, | |
| prompt: str, | |
| optimizer: torch.optim.Optimizer, | |
| save_dir: Optional[str] = None, | |
| ) -> Tuple[PIL.Image.Image, Dict[str, float], Dict[str, float]]: | |
| logging.info(f"Optimizing latents for prompt '{prompt}'.") | |
| best_loss = torch.inf | |
| best_image = None | |
| initial_rewards = None | |
| best_rewards = None | |
| latent_dim = math.prod(latents.shape[1:]) | |
| for iteration in range(self.n_iters): | |
| to_log = "" | |
| rewards = {} | |
| optimizer.zero_grad() | |
| generator = torch.Generator("cuda").manual_seed(self.seed) | |
| if self.imageselect: | |
| new_latents = torch.randn_like( | |
| latents, device=self.device, dtype=latents.dtype | |
| ) | |
| image = self.model.apply( | |
| new_latents, | |
| prompt, | |
| generator=generator, | |
| num_inference_steps=self.n_inference_steps, | |
| ) | |
| else: | |
| image = self.model.apply( | |
| latents, | |
| prompt, | |
| generator=generator, | |
| num_inference_steps=self.n_inference_steps, | |
| ) | |
| if self.no_optim: | |
| best_image = image | |
| break | |
| total_loss = 0 | |
| preprocessed_image = self.preprocess_fn(image) | |
| for reward_loss in self.reward_losses: | |
| loss = reward_loss(preprocessed_image, prompt) | |
| to_log += f"{reward_loss.name}: {loss.item():.4f}, " | |
| total_loss += loss * reward_loss.weighting | |
| rewards[reward_loss.name] = loss.item() | |
| rewards["total"] = total_loss.item() | |
| to_log += f"Total: {total_loss.item():.4f}" | |
| total_reward_loss = total_loss.item() | |
| if self.regularize: | |
| # compute in fp32 to avoid overflow | |
| latent_norm = torch.linalg.vector_norm(latents).to(torch.float32) | |
| log_norm = torch.log(latent_norm) | |
| regularization = self.regularization_weight * ( | |
| 0.5 * latent_norm**2 - (latent_dim - 1) * log_norm | |
| ) | |
| to_log += f", Latent norm: {latent_norm.item()}" | |
| rewards["norm"] = latent_norm.item() | |
| total_loss += regularization.to(total_loss.dtype) | |
| if self.log_metrics: | |
| logging.info(f"Iteration {iteration}: {to_log}") | |
| if initial_rewards is None: | |
| initial_rewards = rewards | |
| if total_reward_loss < best_loss: | |
| best_loss = total_reward_loss | |
| best_image = image | |
| best_rewards = rewards | |
| if iteration != self.n_iters - 1 and not self.imageselect: | |
| total_loss.backward() | |
| torch.nn.utils.clip_grad_norm_(latents, self.grad_clip) | |
| optimizer.step() | |
| if self.save_all_images: | |
| image_numpy = image.detach().cpu().permute(0, 2, 3, 1).float().numpy() | |
| image_pil = DiffusionPipeline.numpy_to_pil(image_numpy)[0] | |
| image_pil.save(f"{save_dir}/{iteration}.png") | |
| image_numpy = best_image.detach().cpu().permute(0, 2, 3, 1).float().numpy() | |
| image_pil = DiffusionPipeline.numpy_to_pil(image_numpy)[0] | |
| return image_pil, initial_rewards, best_rewards | |