from torch import nn as nn
from torch.nn import functional as F
from torch.nn.utils import spectral_norm
from basicsr.utils.registry import ARCH_REGISTRY
@ARCH_REGISTRY.register()
class VGGStyleDiscriminator(nn.Module):
"""VGG style discriminator with input size 128 x 128 or 256 x 256.
It is used to train SRGAN, ESRGAN, and VideoGAN.
Args:
num_in_ch (int): Channel number of inputs. Default: 3.
num_feat (int): Channel number of base intermediate features.Default: 64.
"""
def __init__(self, num_in_ch, num_feat, input_size=128):
super(VGGStyleDiscriminator, self).__init__()
self.input_size = input_size
assert self.input_size == 128 or self.input_size == 256, (
f'input size must be 128 or 256, but received {input_size}')
self.conv0_0 = nn.Conv2d(num_in_ch, num_feat, 3, 1, 1, bias=True)
self.conv0_1 = nn.Conv2d(num_feat, num_feat, 4, 2, 1, bias=False)
self.bn0_1 = nn.BatchNorm2d(num_feat, affine=True)
self.conv1_0 = nn.Conv2d(num_feat, num_feat * 2, 3, 1, 1, bias=False)
self.bn1_0 = nn.BatchNorm2d(num_feat * 2, affine=True)
self.conv1_1 = nn.Conv2d(num_feat * 2, num_feat * 2, 4, 2, 1, bias=False)
self.bn1_1 = nn.BatchNorm2d(num_feat * 2, affine=True)
self.conv2_0 = nn.Conv2d(num_feat * 2, num_feat * 4, 3, 1, 1, bias=False)
self.bn2_0 = nn.BatchNorm2d(num_feat * 4, affine=True)
self.conv2_1 = nn.Conv2d(num_feat * 4, num_feat * 4, 4, 2, 1, bias=False)
self.bn2_1 = nn.BatchNorm2d(num_feat * 4, affine=True)
self.conv3_0 = nn.Conv2d(num_feat * 4, num_feat * 8, 3, 1, 1, bias=False)
self.bn3_0 = nn.BatchNorm2d(num_feat * 8, affine=True)
self.conv3_1 = nn.Conv2d(num_feat * 8, num_feat * 8, 4, 2, 1, bias=False)
self.bn3_1 = nn.BatchNorm2d(num_feat * 8, affine=True)
self.conv4_0 = nn.Conv2d(num_feat * 8, num_feat * 8, 3, 1, 1, bias=False)
self.bn4_0 = nn.BatchNorm2d(num_feat * 8, affine=True)
self.conv4_1 = nn.Conv2d(num_feat * 8, num_feat * 8, 4, 2, 1, bias=False)
self.bn4_1 = nn.BatchNorm2d(num_feat * 8, affine=True)
if self.input_size == 256:
self.conv5_0 = nn.Conv2d(num_feat * 8, num_feat * 8, 3, 1, 1, bias=False)
self.bn5_0 = nn.BatchNorm2d(num_feat * 8, affine=True)
self.conv5_1 = nn.Conv2d(num_feat * 8, num_feat * 8, 4, 2, 1, bias=False)
self.bn5_1 = nn.BatchNorm2d(num_feat * 8, affine=True)
self.linear1 = nn.Linear(num_feat * 8 * 4 * 4, 100)
self.linear2 = nn.Linear(100, 1)
# activation function
self.lrelu = nn.LeakyReLU(negative_slope=0.2, inplace=True)
def forward(self, x):
assert x.size(2) == self.input_size, (f'Input size must be identical to input_size, but received {x.size()}.')
feat = self.lrelu(self.conv0_0(x))
feat = self.lrelu(self.bn0_1(self.conv0_1(feat))) # output spatial size: /2
feat = self.lrelu(self.bn1_0(self.conv1_0(feat)))
feat = self.lrelu(self.bn1_1(self.conv1_1(feat))) # output spatial size: /4
feat = self.lrelu(self.bn2_0(self.conv2_0(feat)))
feat = self.lrelu(self.bn2_1(self.conv2_1(feat))) # output spatial size: /8
feat = self.lrelu(self.bn3_0(self.conv3_0(feat)))
feat = self.lrelu(self.bn3_1(self.conv3_1(feat))) # output spatial size: /16
feat = self.lrelu(self.bn4_0(self.conv4_0(feat)))
feat = self.lrelu(self.bn4_1(self.conv4_1(feat))) # output spatial size: /32
if self.input_size == 256:
feat = self.lrelu(self.bn5_0(self.conv5_0(feat)))
feat = self.lrelu(self.bn5_1(self.conv5_1(feat))) # output spatial size: / 64
# spatial size: (4, 4)
feat = feat.view(feat.size(0), -1)
feat = self.lrelu(self.linear1(feat))
out = self.linear2(feat)
return out
@ARCH_REGISTRY.register(suffix='basicsr')
class UNetDiscriminatorSN(nn.Module):
"""Defines a U-Net discriminator with spectral normalization (SN)
It is used in Real-ESRGAN: Training Real-World Blind Super-Resolution with Pure Synthetic Data.
Arg:
num_in_ch (int): Channel number of inputs. Default: 3.
num_feat (int): Channel number of base intermediate features. Default: 64.
skip_connection (bool): Whether to use skip connections between U-Net. Default: True.
"""
def __init__(self, num_in_ch, num_feat=64, skip_connection=True):
super(UNetDiscriminatorSN, self).__init__()
self.skip_connection = skip_connection
norm = spectral_norm
# the first convolution
self.conv0 = nn.Conv2d(num_in_ch, num_feat, kernel_size=3, stride=1, padding=1)
# downsample
self.conv1 = norm(nn.Conv2d(num_feat, num_feat * 2, 4, 2, 1, bias=False))
self.conv2 = norm(nn.Conv2d(num_feat * 2, num_feat * 4, 4, 2, 1, bias=False))
self.conv3 = norm(nn.Conv2d(num_feat * 4, num_feat * 8, 4, 2, 1, bias=False))
# upsample
self.conv4 = norm(nn.Conv2d(num_feat * 8, num_feat * 4, 3, 1, 1, bias=False))
self.conv5 = norm(nn.Conv2d(num_feat * 4, num_feat * 2, 3, 1, 1, bias=False))
self.conv6 = norm(nn.Conv2d(num_feat * 2, num_feat, 3, 1, 1, bias=False))
# extra convolutions
self.conv7 = norm(nn.Conv2d(num_feat, num_feat, 3, 1, 1, bias=False))
self.conv8 = norm(nn.Conv2d(num_feat, num_feat, 3, 1, 1, bias=False))
self.conv9 = nn.Conv2d(num_feat, 1, 3, 1, 1)
def forward(self, x):
# downsample
x0 = F.leaky_relu(self.conv0(x), negative_slope=0.2, inplace=True)
x1 = F.leaky_relu(self.conv1(x0), negative_slope=0.2, inplace=True)
x2 = F.leaky_relu(self.conv2(x1), negative_slope=0.2, inplace=True)
x3 = F.leaky_relu(self.conv3(x2), negative_slope=0.2, inplace=True)
# upsample
x3 = F.interpolate(x3, scale_factor=2, mode='bilinear', align_corners=False)
x4 = F.leaky_relu(self.conv4(x3), negative_slope=0.2, inplace=True)
if self.skip_connection:
x4 = x4 + x2
x4 = F.interpolate(x4, scale_factor=2, mode='bilinear', align_corners=False)
x5 = F.leaky_relu(self.conv5(x4), negative_slope=0.2, inplace=True)
if self.skip_connection:
x5 = x5 + x1
x5 = F.interpolate(x5, scale_factor=2, mode='bilinear', align_corners=False)
x6 = F.leaky_relu(self.conv6(x5), negative_slope=0.2, inplace=True)
if self.skip_connection:
x6 = x6 + x0
# extra convolutions
out = F.leaky_relu(self.conv7(x6), negative_slope=0.2, inplace=True)
out = F.leaky_relu(self.conv8(out), negative_slope=0.2, inplace=True)
out = self.conv9(out)
return out