### PartialConv 的代码实现
Partial Convolution (PartialConv) 是一种用于图像修复的技术,在处理过程中能够自动更新有效区域掩码,从而更好地保持边界信息。下面是一个基于 PyTorch 实现的 `PartialConv` 层的例子:
```python
import torch
import torch.nn as nn
import torch.nn.functional as F
class PartialConv(nn.Module):
def __init__(self, in_channels, out_channels, kernel_size, stride=1,
padding=0, dilation=1, groups=1, bias=True):
super(PartialConv, self).__init__()
self.input_conv = nn.Conv2d(in_channels, out_channels, kernel_size,
stride=stride, padding=padding, dilation=dilation, groups=groups, bias=bias)
self.mask_conv = nn.Conv2d(in_channels, out_channels, kernel_size,
stride=stride, padding=padding, dilation=dilation, groups=groups, bias=False)
# 将mask_conv层的权重初始化为1
torch.nn.init.constant_(self.mask_conv.weight, 1.0)
# 不需要梯度更新
for param in self.mask_conv.parameters():
param.requires_grad = False
def forward(self, input_tensor, mask_in=None):
output = self.input_conv(input_tensor * mask_in if mask_in is not None else input_tensor)
with torch.no_grad():
if mask_in is not None:
mask_out = self.mask_conv(mask_in)
else:
mask_out = self.mask_conv(torch.ones(1, input_tensor.shape[1], input_tensor.shape[2],
input_tensor.shape[3]).to(device=input_tensor.device))
mask_ratio = 1 / ((mask_out + 1e-8).clone().expand_as(output))
output *= mask_ratio
mask_out = (mask_out >= 1).float()
return output, mask_out
```
此代码定义了一个名为 `PartialConv` 的类,继承自 `nn.Module` 并实现了部分卷积操作。通过重写父类方法 `forward()` 来完成前向传播逻辑[^2]。