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import torch
from torch import nn as nn
from torch.nn import functional as F
from r_basicsr.archs.vgg_arch import VGGFeatureExtractor
from r_basicsr.utils.registry import LOSS_REGISTRY
from .loss_util import weighted_loss
_reduction_modes = ['none', 'mean', 'sum']
@weighted_loss
def l1_loss(pred, target):
return F.l1_loss(pred, target, reduction='none')
@weighted_loss
def mse_loss(pred, target):
return F.mse_loss(pred, target, reduction='none')
@weighted_loss
def charbonnier_loss(pred, target, eps=1e-12):
return torch.sqrt((pred - target)**2 + eps)
@LOSS_REGISTRY.register()
class L1Loss(nn.Module):
"""L1 (mean absolute error, MAE) loss.
Args:
loss_weight (float): Loss weight for L1 loss. Default: 1.0.
reduction (str): Specifies the reduction to apply to the output.
Supported choices are 'none' | 'mean' | 'sum'. Default: 'mean'.
"""
def __init__(self, loss_weight=1.0, reduction='mean'):
super(L1Loss, self).__init__()
if reduction not in ['none', 'mean', 'sum']:
raise ValueError(f'Unsupported reduction mode: {reduction}. Supported ones are: {_reduction_modes}')
self.loss_weight = loss_weight
self.reduction = reduction
def forward(self, pred, target, weight=None, **kwargs):
"""
Args:
pred (Tensor): of shape (N, C, H, W). Predicted tensor.
target (Tensor): of shape (N, C, H, W). Ground truth tensor.
weight (Tensor, optional): of shape (N, C, H, W). Element-wise weights. Default: None.
"""
return self.loss_weight * l1_loss(pred, target, weight, reduction=self.reduction)
@LOSS_REGISTRY.register()
class MSELoss(nn.Module):
"""MSE (L2) loss.
Args:
loss_weight (float): Loss weight for MSE loss. Default: 1.0.
reduction (str): Specifies the reduction to apply to the output.
Supported choices are 'none' | 'mean' | 'sum'. Default: 'mean'.
"""
def __init__(self, loss_weight=1.0, reduction='mean'):
super(MSELoss, self).__init__()
if reduction not in ['none', 'mean', 'sum']:
raise ValueError(f'Unsupported reduction mode: {reduction}. Supported ones are: {_reduction_modes}')
self.loss_weight = loss_weight
self.reduction = reduction
def forward(self, pred, target, weight=None, **kwargs):
"""
Args:
pred (Tensor): of shape (N, C, H, W). Predicted tensor.
target (Tensor): of shape (N, C, H, W). Ground truth tensor.
weight (Tensor, optional): of shape (N, C, H, W). Element-wise weights. Default: None.
"""
return self.loss_weight * mse_loss(pred, target, weight, reduction=self.reduction)
@LOSS_REGISTRY.register()
class CharbonnierLoss(nn.Module):
"""Charbonnier loss (one variant of Robust L1Loss, a differentiable
variant of L1Loss).
Described in "Deep Laplacian Pyramid Networks for Fast and Accurate
Super-Resolution".
Args:
loss_weight (float): Loss weight for L1 loss. Default: 1.0.
reduction (str): Specifies the reduction to apply to the output.
Supported choices are 'none' | 'mean' | 'sum'. Default: 'mean'.
eps (float): A value used to control the curvature near zero. Default: 1e-12.
"""
def __init__(self, loss_weight=1.0, reduction='mean', eps=1e-12):
super(CharbonnierLoss, self).__init__()
if reduction not in ['none', 'mean', 'sum']:
raise ValueError(f'Unsupported reduction mode: {reduction}. Supported ones are: {_reduction_modes}')
self.loss_weight = loss_weight
self.reduction = reduction
self.eps = eps
def forward(self, pred, target, weight=None, **kwargs):
"""
Args:
pred (Tensor): of shape (N, C, H, W). Predicted tensor.
target (Tensor): of shape (N, C, H, W). Ground truth tensor.
weight (Tensor, optional): of shape (N, C, H, W). Element-wise weights. Default: None.
"""
return self.loss_weight * charbonnier_loss(pred, target, weight, eps=self.eps, reduction=self.reduction)
@LOSS_REGISTRY.register()
class WeightedTVLoss(L1Loss):
"""Weighted TV loss.
Args:
loss_weight (float): Loss weight. Default: 1.0.
"""
def __init__(self, loss_weight=1.0, reduction='mean'):
if reduction not in ['mean', 'sum']:
raise ValueError(f'Unsupported reduction mode: {reduction}. Supported ones are: mean | sum')
super(WeightedTVLoss, self).__init__(loss_weight=loss_weight, reduction=reduction)
def forward(self, pred, weight=None):
if weight is None:
y_weight = None
x_weight = None
else:
y_weight = weight[:, :, :-1, :]
x_weight = weight[:, :, :, :-1]
y_diff = super().forward(pred[:, :, :-1, :], pred[:, :, 1:, :], weight=y_weight)
x_diff = super().forward(pred[:, :, :, :-1], pred[:, :, :, 1:], weight=x_weight)
loss = x_diff + y_diff
return loss
@LOSS_REGISTRY.register()
class PerceptualLoss(nn.Module):
"""Perceptual loss with commonly used style loss.
Args:
layer_weights (dict): The weight for each layer of vgg feature.
Here is an example: {'conv5_4': 1.}, which means the conv5_4
feature layer (before relu5_4) will be extracted with weight
1.0 in calculating losses.
vgg_type (str): The type of vgg network used as feature extractor.
Default: 'vgg19'.
use_input_norm (bool): If True, normalize the input image in vgg.
Default: True.
range_norm (bool): If True, norm images with range [-1, 1] to [0, 1].
Default: False.
perceptual_weight (float): If `perceptual_weight > 0`, the perceptual
loss will be calculated and the loss will multiplied by the
weight. Default: 1.0.
style_weight (float): If `style_weight > 0`, the style loss will be
calculated and the loss will multiplied by the weight.
Default: 0.
criterion (str): Criterion used for perceptual loss. Default: 'l1'.
"""
def __init__(self,
layer_weights,
vgg_type='vgg19',
use_input_norm=True,
range_norm=False,
perceptual_weight=1.0,
style_weight=0.,
criterion='l1'):
super(PerceptualLoss, self).__init__()
self.perceptual_weight = perceptual_weight
self.style_weight = style_weight
self.layer_weights = layer_weights
self.vgg = VGGFeatureExtractor(
layer_name_list=list(layer_weights.keys()),
vgg_type=vgg_type,
use_input_norm=use_input_norm,
range_norm=range_norm)
self.criterion_type = criterion
if self.criterion_type == 'l1':
self.criterion = torch.nn.L1Loss()
elif self.criterion_type == 'l2':
self.criterion = torch.nn.L2loss()
elif self.criterion_type == 'fro':
self.criterion = None
else:
raise NotImplementedError(f'{criterion} criterion has not been supported.')
def forward(self, x, gt):
"""Forward function.
Args:
x (Tensor): Input tensor with shape (n, c, h, w).
gt (Tensor): Ground-truth tensor with shape (n, c, h, w).
Returns:
Tensor: Forward results.
"""
# extract vgg features
x_features = self.vgg(x)
gt_features = self.vgg(gt.detach())
# calculate perceptual loss
if self.perceptual_weight > 0:
percep_loss = 0
for k in x_features.keys():
if self.criterion_type == 'fro':
percep_loss += torch.norm(x_features[k] - gt_features[k], p='fro') * self.layer_weights[k]
else:
percep_loss += self.criterion(x_features[k], gt_features[k]) * self.layer_weights[k]
percep_loss *= self.perceptual_weight
else:
percep_loss = None
# calculate style loss
if self.style_weight > 0:
style_loss = 0
for k in x_features.keys():
if self.criterion_type == 'fro':
style_loss += torch.norm(
self._gram_mat(x_features[k]) - self._gram_mat(gt_features[k]), p='fro') * self.layer_weights[k]
else:
style_loss += self.criterion(self._gram_mat(x_features[k]), self._gram_mat(
gt_features[k])) * self.layer_weights[k]
style_loss *= self.style_weight
else:
style_loss = None
return percep_loss, style_loss
def _gram_mat(self, x):
"""Calculate Gram matrix.
Args:
x (torch.Tensor): Tensor with shape of (n, c, h, w).
Returns:
torch.Tensor: Gram matrix.
"""
n, c, h, w = x.size()
features = x.view(n, c, w * h)
features_t = features.transpose(1, 2)
gram = features.bmm(features_t) / (c * h * w)
return gram
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