ResNet101和ASPP
model = ResNet(nInputChannels, Bottleneck, [3, 4, 23, 3], os, pretrained=pretrained)
nInputChannels=3,os=16,其中Bottleneck是一个网络:class Bottleneck(nn.Module)
先看Bottleneck网络:
class Bottleneck(nn.Module):
expansion = 4
def __init__(self, inplanes, planes, stride=1, rate=1, downsample=None):
super(Bottleneck, self).__init__()
self.conv1 = nn.Conv2d(inplanes, planes, kernel_size=1, bias=False)
self.bn1 = nn.BatchNorm2d(planes)
self.conv2 = nn.Conv2d(planes, planes, kernel_size=3, stride=stride,
dilation=rate, padding=rate, bias=False)
self.bn2 = nn.BatchNorm2d(planes)
self.conv3 = nn.Conv2d(planes, planes * 4, kernel_size=1, bias=False)
self.bn3 = nn.BatchNorm2d(planes * 4)
self.relu = nn.ReLU(inplace=True) # 会改变输入的数据,使得输入的数据和输出数据一样
self.downsample = downsample
self.stride = stride
self.rate = rate
def forward(self, x):
residual = x
out = self.conv1(x)
out = self.bn1(out)
out = self.relu(out)
out = self.conv2(out)
out = self.bn2(out)
out = self.relu(out)
out = self.conv3(out)
out = self.bn3(out)
if self.downsample is not None:
residual = self.downsample(x)
out += residual
out = self.relu(out)
return out
这是一个bottleneck,输入是x,输出是output+residual。这两个tensor的shape是一样的才能允许相加,如果输入的shape不等于输出的shape那么一定存在downsample,进行shape的变化。所有的卷积都不添加bias,所有的输入经过relu函数之后都改变了数值,使得和输出是一样的。
这里的卷积大小计算重申一下: [n+2p-r(k-1)+1]/s +1
再看resnet101网络,里面有6个函数,下面就一个一个讲解
class ResNet(nn.Module):
def __init__(self, nInputChannels, block, layers, os=16, pretrained=False):
pass
def _make_layer(self, block, planes, blocks, stride=1, rate=1):
pass
def _make_MG_unit(self, block, planes, blocks=[1,2,4], stride=1, rate=1):
pass
def forward(self, input):
pass
def _init_weight(self):
pass
def _load_pretrained_model(self):
pass