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import torch
import torch.nn as nn
from criteria.lpips.networks import get_network, LinLayers
from criteria.lpips.utils import get_state_dict
class LPIPS(nn.Module):
r"""Creates a criterion that measures
Learned Perceptual Image Patch Similarity (LPIPS).
Arguments:
net_type (str): the network type to compare the features:
'alex' | 'squeeze' | 'vgg'. Default: 'alex'.
version (str): the version of LPIPS. Default: 0.1.
"""
def __init__(self, net_type: str = 'alex', version: str = '0.1'):
assert version in ['0.1'], 'v0.1 is only supported now'
super(LPIPS, self).__init__()
# pretrained network
self.net = get_network(net_type).to("cuda")
# linear layers
self.lin = LinLayers(self.net.n_channels_list).to("cuda")
self.lin.load_state_dict(get_state_dict(net_type, version))
def forward(self, x: torch.Tensor, y: torch.Tensor):
feat_x, feat_y = self.net(x), self.net(y)
diff = [(fx - fy) ** 2 for fx, fy in zip(feat_x, feat_y)]
res = [l(d).mean((2, 3), True) for d, l in zip(diff, self.lin)]
return torch.sum(torch.cat(res, 0)) / x.shape[0]
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