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| import huggingface_hub | |
| import torch | |
| from hpsv2.src.open_clip import create_model, get_tokenizer | |
| from rewards.base_reward import BaseRewardLoss | |
| class HPSLoss(BaseRewardLoss): | |
| """HPS reward loss function for optimization.""" | |
| def __init__( | |
| self, | |
| weighting: float, | |
| dtype: torch.dtype, | |
| device: torch.device, | |
| cache_dir: str, | |
| memsave: bool = False, | |
| ): | |
| self.hps_model = create_model( | |
| "ViT-H-14", | |
| "laion2B-s32B-b79K", | |
| precision=dtype, | |
| device=device, | |
| cache_dir=cache_dir, | |
| ) | |
| checkpoint_path = huggingface_hub.hf_hub_download( | |
| "xswu/HPSv2", "HPS_v2.1_compressed.pt", cache_dir=cache_dir | |
| ) | |
| self.hps_model.load_state_dict( | |
| torch.load(checkpoint_path, map_location=device)["state_dict"] | |
| ) | |
| self.hps_tokenizer = get_tokenizer("ViT-H-14") | |
| if memsave: | |
| import memsave_torch.nn | |
| self.hps_model = memsave_torch.nn.convert_to_memory_saving(self.hps_model) | |
| self.hps_model = self.hps_model.to(device, dtype=dtype) | |
| self.hps_model.eval() | |
| self.freeze_parameters(self.hps_model.parameters()) | |
| super().__init__("HPS", weighting) | |
| self.hps_model.set_grad_checkpointing(True) | |
| def get_image_features(self, image: torch.Tensor) -> torch.Tensor: | |
| hps_image_features = self.hps_model.encode_image(image) | |
| return hps_image_features | |
| def get_text_features(self, prompt: str) -> torch.Tensor: | |
| hps_text = self.hps_tokenizer(prompt).to("cuda") | |
| hps_text_features = self.hps_model.encode_text(hps_text) | |
| return hps_text_features | |
| def compute_loss( | |
| self, image_features: torch.Tensor, text_features: torch.Tensor | |
| ) -> torch.Tensor: | |
| logits_per_image = image_features @ text_features.T | |
| hps_loss = 1 - torch.diagonal(logits_per_image)[0] | |
| return hps_loss | |