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# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserve.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# code was heavily based on https://github.com/rosinality/stylegan2-pytorch
# MIT License
# Copyright (c) 2019 Kim Seonghyeon
import math
import paddle
import paddle.nn as nn
import paddle.nn.functional as F
from .fused_act import fused_leaky_relu
class EqualConv2D(nn.Layer):
"""This convolutional layer class stabilizes the learning rate changes of its parameters.
Equalizing learning rate keeps the weights in the network at a similar scale during training.
"""
def __init__(self,
in_channel,
out_channel,
kernel_size,
stride=1,
padding=0,
bias=True):
super().__init__()
self.weight = self.create_parameter(
(out_channel, in_channel, kernel_size, kernel_size),
default_initializer=nn.initializer.Normal())
self.scale = 1 / math.sqrt(in_channel * (kernel_size * kernel_size))
self.stride = stride
self.padding = padding
if bias:
self.bias = self.create_parameter((out_channel, ),
nn.initializer.Constant(0.0))
else:
self.bias = None
def forward(self, input):
out = F.conv2d(
input,
self.weight * self.scale,
bias=self.bias,
stride=self.stride,
padding=self.padding, )
return out
def __repr__(self):
return (
f"{self.__class__.__name__}({self.weight.shape[1]}, {self.weight.shape[0]},"
f" {self.weight.shape[2]}, stride={self.stride}, padding={self.padding})"
)
class EqualLinear(nn.Layer):
"""This linear layer class stabilizes the learning rate changes of its parameters.
Equalizing learning rate keeps the weights in the network at a similar scale during training.
"""
def __init__(self,
in_dim,
out_dim,
bias=True,
bias_init=0,
lr_mul=1,
activation=None):
super().__init__()
self.weight = self.create_parameter(
(in_dim, out_dim), default_initializer=nn.initializer.Normal())
self.weight.set_value((self.weight / lr_mul))
if bias:
self.bias = self.create_parameter(
(out_dim, ), nn.initializer.Constant(bias_init))
else:
self.bias = None
self.activation = activation
self.scale = (1 / math.sqrt(in_dim)) * lr_mul
self.lr_mul = lr_mul
def forward(self, input):
if self.activation:
out = F.linear(input, self.weight * self.scale)
out = fused_leaky_relu(out, self.bias * self.lr_mul)
else:
out = F.linear(
input, self.weight * self.scale, bias=self.bias * self.lr_mul)
return out
def __repr__(self):
return (
f"{self.__class__.__name__}({self.weight.shape[0]}, {self.weight.shape[1]})"
)