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import math
import torch
import torch.nn as nn
import torch.nn.functional as F
def default_conv(in_channels, out_channels, kernel_size,stride=1, bias=True):
return nn.Conv2d(
in_channels, out_channels, kernel_size,
padding=(kernel_size//2),stride=stride, bias=bias)
def spectral_conv(in_channels, out_channels, kernel_size,stride=1, bias=True):
return nn.utils.spectral_norm(nn.Conv2d(
in_channels, out_channels, kernel_size,
padding=(kernel_size//2),stride=stride, bias=bias))
class MeanShift(nn.Conv2d):
def __init__(
self, rgb_range,
rgb_mean=(0.4488, 0.4371, 0.4040), rgb_std=(1.0, 1.0, 1.0), sign=-1):
super(MeanShift, self).__init__(3, 3, kernel_size=1)
std = torch.Tensor(rgb_std)
self.weight.data = torch.eye(3).view(3, 3, 1, 1) / std.view(3, 1, 1, 1)
self.bias.data = sign * rgb_range * torch.Tensor(rgb_mean) / std
for p in self.parameters():
p.requires_grad = False
class BasicBlock(nn.Sequential):
def __init__(
self, conv, in_channels, out_channels, kernel_size, stride=1, bias=True,
bn=False, act=nn.PReLU()):
m = [conv(in_channels, out_channels, kernel_size, bias=bias)]
if bn:
m.append(nn.BatchNorm2d(out_channels))
if act is not None:
m.append(act)
super(BasicBlock, self).__init__(*m)
class ResBlock(nn.Module):
def __init__(
self, conv, n_feats, kernel_size,
bias=True, bn=False, act=nn.PReLU(), res_scale=1):
super(ResBlock, self).__init__()
m = []
for i in range(2):
m.append(conv(n_feats, n_feats, kernel_size, bias=bias))
if bn:
m.append(nn.BatchNorm2d(n_feats))
if i == 0:
m.append(act)
self.body = nn.Sequential(*m)
self.res_scale = res_scale
def forward(self, x):
res = self.body(x).mul(self.res_scale)
res += x
return res
class Upsampler(nn.Sequential):
def __init__(self, conv, scale, n_feats, bn=False, act=False, bias=True):
m = []
if (scale & (scale - 1)) == 0: # Is scale = 2^n?
for _ in range(int(math.log(scale, 2))):
m.append(conv(n_feats, 4 * n_feats, 3, bias))
m.append(nn.PixelShuffle(2))
if bn:
m.append(nn.BatchNorm2d(n_feats))
if act == 'relu':
m.append(nn.ReLU(True))
elif act == 'prelu':
m.append(nn.PReLU(n_feats))
elif scale == 3:
m.append(conv(n_feats, 9 * n_feats, 3, bias))
m.append(nn.PixelShuffle(3))
if bn:
m.append(nn.BatchNorm2d(n_feats))
if act == 'relu':
m.append(nn.ReLU(True))
elif act == 'prelu':
m.append(nn.PReLU(n_feats))
else:
raise NotImplementedError
super(Upsampler, self).__init__(*m)
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