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# https://github.com/XPixelGroup/ClassSR
import math
import torch
import torch.nn as nn
import torch.nn.init as init
import torch.nn.functional as F
def initialize_weights(net_l, scale=1):
if not isinstance(net_l, list):
net_l = [net_l]
for net in net_l:
for m in net.modules():
if isinstance(m, nn.Conv2d):
init.kaiming_normal_(m.weight, a=0, mode='fan_in')
m.weight.data *= scale # for residual block
if m.bias is not None:
m.bias.data.zero_()
elif isinstance(m, nn.Linear):
init.kaiming_normal_(m.weight, a=0, mode='fan_in')
m.weight.data *= scale
if m.bias is not None:
m.bias.data.zero_()
elif isinstance(m, nn.BatchNorm2d):
init.constant_(m.weight, 1)
init.constant_(m.bias.data, 0.0)
def make_layer(block, n_layers):
layers = []
for _ in range(n_layers):
layers.append(block())
return nn.Sequential(*layers)
class ResidualBlock_noBN(nn.Module):
'''Residual block w/o BN
---Conv-ReLU-Conv-+-
|________________|
'''
def __init__(self, nf=64):
super(ResidualBlock_noBN, self).__init__()
self.conv1 = nn.Conv2d(nf, nf, 3, 1, 1, bias=True)
self.conv2 = nn.Conv2d(nf, nf, 3, 1, 1, bias=True)
# initialization
initialize_weights([self.conv1, self.conv2], 0.1)
def forward(self, x):
identity = x
out = F.relu(self.conv1(x), inplace=True)
out = self.conv2(out)
return identity + out
def default_conv(in_channels, out_channels, kernel_size, bias=True):
return nn.Conv2d(
in_channels, out_channels, kernel_size,
padding=(kernel_size//2), bias=bias)
class MeanShift(nn.Conv2d):
def __init__(self, rgb_range, rgb_mean, rgb_std, 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)
self.weight.data.div_(std.view(3, 1, 1, 1))
self.bias.data = sign * rgb_range * torch.Tensor(rgb_mean)
self.bias.data.div_(std)
self.requires_grad = False
class BasicBlock(nn.Sequential):
def __init__(
self, in_channels, out_channels, kernel_size, stride=1, bias=False,
bn=True, act=nn.ReLU(True)):
m = [nn.Conv2d(
in_channels, out_channels, kernel_size,
padding=(kernel_size//2), stride=stride, 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_feat, kernel_size,
bias=True, bn=False, act=nn.ReLU(True), res_scale=1):
super(ResBlock, self).__init__()
m = []
for i in range(2):
m.append(conv(n_feat, n_feat, kernel_size, bias=bias))
if bn: m.append(nn.BatchNorm2d(n_feat))
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_feat, 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_feat, 4 * n_feat, 3, bias))
m.append(nn.PixelShuffle(2))
if bn: m.append(nn.BatchNorm2d(n_feat))
if act: m.append(act())
elif scale == 3:
m.append(conv(n_feat, 9 * n_feat, 3, bias))
m.append(nn.PixelShuffle(3))
if bn: m.append(nn.BatchNorm2d(n_feat))
if act: m.append(act())
else:
raise NotImplementedError
super(Upsampler, self).__init__(*m)
class EResidualBlock(nn.Module):
def __init__(self,
in_channels, out_channels,
group=1):
super(EResidualBlock, self).__init__()
self.body = nn.Sequential(
nn.Conv2d(in_channels, out_channels, 3, 1, 1, groups=group),
nn.ReLU(inplace=True),
nn.Conv2d(out_channels, out_channels, 3, 1, 1, groups=group),
nn.ReLU(inplace=True),
nn.Conv2d(out_channels, out_channels, 1, 1, 0),
)
def forward(self, x):
out = self.body(x)
out = F.relu(out + x)
return out
class Upsampler(nn.Sequential):
def __init__(self, conv, scale, n_feat, 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_feat, 4 * n_feat, 3, bias))
m.append(nn.PixelShuffle(2))
if bn: m.append(nn.BatchNorm2d(n_feat))
if act: m.append(act())
elif scale == 3:
m.append(conv(n_feat, 9 * n_feat, 3, bias))
m.append(nn.PixelShuffle(3))
if bn: m.append(nn.BatchNorm2d(n_feat))
if act: m.append(act())
else:
raise NotImplementedError
super(Upsampler, self).__init__(*m)
class UpsampleBlock(nn.Module):
def __init__(self,
n_channels, scale, multi_scale,
group=1):
super(UpsampleBlock, self).__init__()
if multi_scale:
self.up2 = _UpsampleBlock(n_channels, scale=2, group=group)
self.up3 = _UpsampleBlock(n_channels, scale=3, group=group)
self.up4 = _UpsampleBlock(n_channels, scale=4, group=group)
else:
self.up = _UpsampleBlock(n_channels, scale=scale, group=group)
self.multi_scale = multi_scale
def forward(self, x, scale):
if self.multi_scale:
if scale == 2:
return self.up2(x)
elif scale == 3:
return self.up3(x)
elif scale == 4:
return self.up4(x)
else:
return self.up(x)
class _UpsampleBlock(nn.Module):
def __init__(self,
n_channels, scale,
group=1):
super(_UpsampleBlock, self).__init__()
modules = []
if scale == 2 or scale == 4 or scale == 8:
for _ in range(int(math.log(scale, 2))):
modules += [nn.Conv2d(n_channels, 4 * n_channels, 3, 1, 1, groups=group), nn.ReLU(inplace=True)]
modules += [nn.PixelShuffle(2)]
elif scale == 3:
modules += [nn.Conv2d(n_channels, 9 * n_channels, 3, 1, 1, groups=group), nn.ReLU(inplace=True)]
modules += [nn.PixelShuffle(3)]
self.body = nn.Sequential(*modules)
def forward(self, x):
out = self.body(x)
return out |