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unet.py
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import torch
import torch.nn as nn
import functools
class UnetGenerator(nn.Module):
"""Create a Unet-based generator"""
def __init__(self, input_nc=6, output_nc=3, num_downs=8, ngf=64, norm_layer=nn.BatchNorm2d, use_dropout=True):
"""Construct a Unet generator
Parameters:
input_nc (int) -- the number of channels in input images
output_nc (int) -- the number of channels in output images
num_downs (int) -- the number of downsamplings in UNet. For example, # if |num_downs| == 7,
image of size 128x128 will become of size 1x1 # at the bottleneck
ngf (int) -- the number of filters in the last conv layer
norm_layer -- normalization layer
We construct the U-Net from the innermost layer to the outermost layer.
It is a recursive process.
"""
super(UnetGenerator, self).__init__()
# construct unet structure
unet_block = UnetSkipConnectionBlock(ngf * 8, ngf * 8, input_nc=None, submodule=None, norm_layer=norm_layer, innermost=True) # add the innermost layer
for i in range(num_downs - 5): # add intermediate layers with ngf * 8 filters
unet_block = UnetSkipConnectionBlock(ngf * 8, ngf * 8, input_nc=None, submodule=unet_block, norm_layer=norm_layer, use_dropout=use_dropout)
# gradually reduce the number of filters from ngf * 8 to ngf
unet_block = UnetSkipConnectionBlock(ngf * 4, ngf * 8, input_nc=None, submodule=unet_block, norm_layer=norm_layer)
unet_block = UnetSkipConnectionBlock(ngf * 2, ngf * 4, input_nc=None, submodule=unet_block, norm_layer=norm_layer)
unet_block = UnetSkipConnectionBlock(ngf, ngf * 2, input_nc=None, submodule=unet_block, norm_layer=norm_layer)
self.model = UnetSkipConnectionBlock(output_nc, ngf, input_nc=input_nc, submodule=unet_block, outermost=True, norm_layer=norm_layer) # add the outermost layer
def forward(self, input):
"""Standard forward"""
return self.model(input)
class UnetSkipConnectionBlock(nn.Module):
"""Defines the Unet submodule with skip connection.
X -------------------identity----------------------
|-- downsampling -- |submodule| -- upsampling --|
"""
def __init__(self, outer_nc, inner_nc, input_nc=None,
submodule=None, outermost=False, innermost=False, norm_layer=nn.BatchNorm2d, use_dropout=False):
"""Construct a Unet submodule with skip connections.
Parameters:
outer_nc (int) -- the number of filters in the outer conv layer
inner_nc (int) -- the number of filters in the inner conv layer
input_nc (int) -- the number of channels in input images/features
submodule (UnetSkipConnectionBlock) -- previously defined submodules
outermost (bool) -- if this module is the outermost module
innermost (bool) -- if this module is the innermost module
norm_layer -- normalization layer
use_dropout (bool) -- if use dropout layers.
"""
super(UnetSkipConnectionBlock, self).__init__()
self.outermost = outermost
if type(norm_layer) == functools.partial:
use_bias = norm_layer.func == nn.InstanceNorm2d
else:
use_bias = norm_layer == nn.InstanceNorm2d
if input_nc is None:
input_nc = outer_nc
downconv = nn.Conv2d(input_nc, inner_nc, kernel_size=4,
stride=2, padding=1, bias=use_bias)
downrelu = nn.LeakyReLU(0.2, True)
downnorm = norm_layer(inner_nc)
uprelu = nn.ReLU(True)
upnorm = norm_layer(outer_nc)
if outermost:
upconv = nn.ConvTranspose2d(inner_nc * 2, outer_nc,
kernel_size=4, stride=2,
padding=1)
down = [downconv]
up = [uprelu, upconv, nn.Tanh()]
model = down + [submodule] + up
elif innermost:
upconv = nn.ConvTranspose2d(inner_nc, outer_nc,
kernel_size=4, stride=2,
padding=1, bias=use_bias)
down = [downrelu, downconv]
up = [uprelu, upconv, upnorm]
model = down + up
else:
upconv = nn.ConvTranspose2d(inner_nc * 2, outer_nc,
kernel_size=4, stride=2,
padding=1, bias=use_bias)
down = [downrelu, downconv, downnorm]
up = [uprelu, upconv, upnorm]
if use_dropout:
model = down + [submodule] + up + [nn.Dropout(0.5)]
else:
model = down + [submodule] + up
self.model = nn.Sequential(*model)
def forward(self, x):
# for name, parms in self.model.named_parameters():
# print('-->name:', name, '-->grad_requirs:',parms.requires_grad,
# ' -->grad_value:',parms.grad)
if self.outermost:
x = self.model(x)
return x
else:
return torch.cat([x, self.model(x)], 1)
class G(nn.Module):
def __init__(self):
super(G, self).__init__()
self.conv1 = ConvLayer(6, 32, kernel_size=9, stride=1)
self.conv2 = ConvLayer(32, 64, kernel_size=3, stride=2)
self.conv3 = ConvLayer(64, 128, kernel_size=3, stride=2)
self.res1 = ResidualBlock(128)
self.res2 = ResidualBlock(128)
self.res3 = ResidualBlock(128)
self.res4 = ResidualBlock(128)
self.deconv1 = UpsampleConvLayer(128*2, 64, kernel_size=3, stride=1, upsample=2)
self.in4 = torch.nn.InstanceNorm2d(64, affine=True)
self.deconv2 = UpsampleConvLayer(64*2, 32, kernel_size=3, stride=1, upsample=2)
self.in5 = torch.nn.InstanceNorm2d(32, affine=True)
self.deconv3 = ConvLayer(32*2, 3, kernel_size=9, stride=1)
self.relu = torch.nn.ReLU()
def forward(self, vis, nir):
X = torch.cat([nir, vis], dim=1)
o1 = self.relu(self.conv1(X))
o2 = self.relu(self.conv2(o1))
o3 = self.relu(self.conv3(o2))
y = self.res1(o3)
y = self.res2(y)
y = self.res3(y)
y = self.res4(y)
in1 = torch.cat( (y, o3), 1 )
y = self.relu(self.deconv1(in1))
in2 = torch.cat( (y, o2), 1 )
y = self.relu(self.deconv2(in2))
in3 = torch.cat( (y, o1), 1 )
y = self.deconv3(in3)
return y
class ConvLayer(torch.nn.Module):
def __init__(self, in_channels, out_channels, kernel_size, stride):
super(ConvLayer, self).__init__()
reflection_padding = kernel_size // 2
self.reflection_pad = torch.nn.ReflectionPad2d(reflection_padding)
self.conv2d = torch.nn.Conv2d(in_channels, out_channels, kernel_size, stride)
def forward(self, x):
out = self.reflection_pad(x)
out = self.conv2d(out)
return out
class ResidualBlock(torch.nn.Module):
def __init__(self, channels):
super(ResidualBlock, self).__init__()
self.conv1 = ConvLayer(channels, channels, kernel_size=3, stride=1)
self.in1 = torch.nn.InstanceNorm2d(channels, affine=True)
self.conv2 = ConvLayer(channels, channels, kernel_size=3, stride=1)
self.in2 = torch.nn.InstanceNorm2d(channels, affine=True)
self.relu = torch.nn.ReLU()
def forward(self, x):
residual = x
out = self.relu(self.conv1(x))
out = self.conv2(out)
out = out + residual
return out
class UpsampleConvLayer(torch.nn.Module):
def __init__(self, in_channels, out_channels, kernel_size, stride, upsample=None):
super(UpsampleConvLayer, self).__init__()
self.upsample = upsample
reflection_padding = kernel_size // 2
self.reflection_pad = torch.nn.ReflectionPad2d(reflection_padding)
self.conv2d = torch.nn.Conv2d(in_channels, out_channels, kernel_size, stride)
def forward(self, x):
x_in = x
if self.upsample:
x_in = torch.nn.functional.interpolate(x_in, mode='nearest', scale_factor=self.upsample)
out = self.reflection_pad(x_in)
out = self.conv2d(out)
return out