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# -*- coding: utf-8 -*-
import torch
import torch.nn as nn
from torch.nn.parameter import Parameter
from torch.nn import functional as F
import numpy as np
class NormLayer(nn.Module):
"""Normalization Layers.
------------
# Arguments
- channels: input channels, for batch norm and instance norm.
- input_size: input shape without batch size, for layer norm.
"""
def __init__(self, channels, normalize_shape=None, norm_type='bn', ref_channels=None):
super(NormLayer, self).__init__()
norm_type = norm_type.lower()
self.norm_type = norm_type
if norm_type == 'bn':
self.norm = nn.BatchNorm2d(channels, affine=True)
elif norm_type == 'in':
self.norm = nn.InstanceNorm2d(channels, affine=False)
elif norm_type == 'gn':
self.norm = nn.GroupNorm(32, channels, affine=True)
elif norm_type == 'pixel':
self.norm = lambda x: F.normalize(x, p=2, dim=1)
elif norm_type == 'layer':
self.norm = nn.LayerNorm(normalize_shape)
elif norm_type == 'none':
self.norm = lambda x: x*1.0
else:
assert 1==0, 'Norm type {} not support.'.format(norm_type)
def forward(self, x, ref=None):
if self.norm_type == 'spade':
return self.norm(x, ref)
else:
return self.norm(x)
class ReluLayer(nn.Module):
"""Relu Layer.
------------
# Arguments
- relu type: type of relu layer, candidates are
- ReLU
- LeakyReLU: default relu slope 0.2
- PRelu
- SELU
- none: direct pass
"""
def __init__(self, channels, relu_type='relu'):
super(ReluLayer, self).__init__()
relu_type = relu_type.lower()
if relu_type == 'relu':
self.func = nn.ReLU(True)
elif relu_type == 'leakyrelu':
self.func = nn.LeakyReLU(0.2, inplace=True)
elif relu_type == 'prelu':
self.func = nn.PReLU(channels)
elif relu_type == 'selu':
self.func = nn.SELU(True)
elif relu_type == 'none':
self.func = lambda x: x*1.0
else:
assert 1==0, 'Relu type {} not support.'.format(relu_type)
def forward(self, x):
return self.func(x)
class ConvLayer(nn.Module):
def __init__(self, in_channels, out_channels, kernel_size=3, scale='none', norm_type='none', relu_type='none', use_pad=True, bias=True):
super(ConvLayer, self).__init__()
self.use_pad = use_pad
self.norm_type = norm_type
if norm_type in ['bn']:
bias = False
stride = 2 if scale == 'down' else 1
self.scale_func = lambda x: x
if scale == 'up':
self.scale_func = lambda x: nn.functional.interpolate(x, scale_factor=2, mode='nearest')
self.reflection_pad = nn.ReflectionPad2d(int(np.ceil((kernel_size - 1.)/2)))
self.conv2d = nn.Conv2d(in_channels, out_channels, kernel_size, stride, bias=bias)
self.relu = ReluLayer(out_channels, relu_type)
self.norm = NormLayer(out_channels, norm_type=norm_type)
def forward(self, x):
out = self.scale_func(x)
if self.use_pad:
out = self.reflection_pad(out)
out = self.conv2d(out)
out = self.norm(out)
out = self.relu(out)
return out
class ResidualBlock(nn.Module):
"""
Residual block recommended in: http://torch.ch/blog/2016/02/04/resnets.html
"""
def __init__(self, c_in, c_out, relu_type='prelu', norm_type='bn', scale='none'):
super(ResidualBlock, self).__init__()
if scale == 'none' and c_in == c_out:
self.shortcut_func = lambda x: x
else:
self.shortcut_func = ConvLayer(c_in, c_out, 3, scale)
scale_config_dict = {'down': ['none', 'down'], 'up': ['up', 'none'], 'none': ['none', 'none']}
scale_conf = scale_config_dict[scale]
self.conv1 = ConvLayer(c_in, c_out, 3, scale_conf[0], norm_type=norm_type, relu_type=relu_type)
self.conv2 = ConvLayer(c_out, c_out, 3, scale_conf[1], norm_type=norm_type, relu_type='none')
def forward(self, x):
identity = self.shortcut_func(x)
res = self.conv1(x)
res = self.conv2(res)
return identity + res
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