soon is now

sgm/modules/diffusionmodules/loss.py

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+from typing import List, Optional, Union
+
+import torch
+import torch.nn as nn
+from omegaconf import ListConfig
+from taming.modules.losses.lpips import LPIPS
+
+from ...util import append_dims, instantiate_from_config
+
+
+class StandardDiffusionLoss(nn.Module):
+    def __init__(
+        self,
+        sigma_sampler_config,
+        type="l2",
+        offset_noise_level=0.0,
+        batch2model_keys: Optional[Union[str, List[str], ListConfig]] = None,
+    ):
+        super().__init__()
+
+        assert type in ["l2", "l1", "lpips"]
+
+        self.sigma_sampler = instantiate_from_config(sigma_sampler_config)
+
+        self.type = type
+        self.offset_noise_level = offset_noise_level
+
+        if type == "lpips":
+            self.lpips = LPIPS().eval()
+
+        if not batch2model_keys:
+            batch2model_keys = []
+
+        if isinstance(batch2model_keys, str):
+            batch2model_keys = [batch2model_keys]
+
+        self.batch2model_keys = set(batch2model_keys)
+
+    def __call__(self, network, denoiser, conditioner, input, batch):
+        cond = conditioner(batch)
+        additional_model_inputs = {
+            key: batch[key] for key in self.batch2model_keys.intersection(batch)
+        }
+
+        sigmas = self.sigma_sampler(input.shape[0]).to(input.device)
+        noise = torch.randn_like(input)
+        if self.offset_noise_level > 0.0:
+            noise = noise + self.offset_noise_level * append_dims(
+                torch.randn(input.shape[0], device=input.device), input.ndim
+            )
+        noised_input = input + noise * append_dims(sigmas, input.ndim)
+        model_output = denoiser(
+            network, noised_input, sigmas, cond, **additional_model_inputs
+        )
+        w = append_dims(denoiser.w(sigmas), input.ndim)
+        return self.get_loss(model_output, input, w)
+
+    def get_loss(self, model_output, target, w):
+        if self.type == "l2":
+            return torch.mean(
+                (w * (model_output - target) ** 2).reshape(target.shape[0], -1), 1
+            )
+        elif self.type == "l1":
+            return torch.mean(
+                (w * (model_output - target).abs()).reshape(target.shape[0], -1), 1
+            )
+        elif self.type == "lpips":
+            loss = self.lpips(model_output, target).reshape(-1)
+            return loss