import torch
import torch.nn as nn
import lpips
from model.vgg_arch import VGGFeatureExtractor
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 calculting 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 == 'mse':
self.criterion = torch.nn.MSELoss(reduction='mean')
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
class LPIPSLoss(nn.Module):
def __init__(self,
loss_weight=1.0,
use_input_norm=True,
range_norm=False,):
super(LPIPSLoss, self).__init__()
self.perceptual = lpips.LPIPS(net="vgg", spatial=False).eval()
self.loss_weight = loss_weight
self.use_input_norm = use_input_norm
self.range_norm = range_norm
if self.use_input_norm:
# the mean is for image with range [0, 1]
self.register_buffer('mean', torch.Tensor([0.485, 0.456, 0.406]).view(1, 3, 1, 1))
# the std is for image with range [0, 1]
self.register_buffer('std', torch.Tensor([0.229, 0.224, 0.225]).view(1, 3, 1, 1))
def forward(self, pred, target):
if self.range_norm:
pred = (pred + 1) / 2
target = (target + 1) / 2
if self.use_input_norm:
pred = (pred - self.mean) / self.std
target = (target - self.mean) / self.std
lpips_loss = self.perceptual(target.contiguous(), pred.contiguous())
return self.loss_weight * lpips_loss.mean(), None
class AdversarialLoss(nn.Module):
r"""
Adversarial loss
https://arxiv.org/abs/1711.10337
"""
def __init__(self,
type='nsgan',
target_real_label=1.0,
target_fake_label=0.0):
r"""
type = nsgan | lsgan | hinge
"""
super(AdversarialLoss, self).__init__()
self.type = type
self.register_buffer('real_label', torch.tensor(target_real_label))
self.register_buffer('fake_label', torch.tensor(target_fake_label))
if type == 'nsgan':
self.criterion = nn.BCELoss()
elif type == 'lsgan':
self.criterion = nn.MSELoss()
elif type == 'hinge':
self.criterion = nn.ReLU()
def __call__(self, outputs, is_real, is_disc=None):
if self.type == 'hinge':
if is_disc:
if is_real:
outputs = -outputs
return self.criterion(1 + outputs).mean()
else:
return (-outputs).mean()
else:
labels = (self.real_label
if is_real else self.fake_label).expand_as(outputs)
loss = self.criterion(outputs, labels)
return loss