经典CNN算法解析实战-第J4周:ResNet与DenseNet结合探索

一、课题背景和开发环境

📌第J4周:ResNet与DenseNet结合探索📌

  • 语言:Python3、Pytorch
  • 📌本周任务:📌
    任务类型: 自主探索
    任务难度: 偏难
    任务描述:
    Ⅰ.请根据J1~J3周的内容自由探索ResNetDenseNet结合的可能性
    Ⅱ.是否可以根据两种特性构建一个新的模型框架?
    Ⅲ.请用之前的任一图像识别任务验证改进后的模型的效果

🔊注: 打卡内容应该包括创新的思路以及对应模型结构图、代码运行截图

二、网络结构

在网上找到了一个ResNet与DenseNet复合的网络框架DPN,本次课题就以实现DPN(Dual Path Networks)为主。
Dual Path Networks
Dual Path Networks
DPN92网络结构图

参考资料:
Higher Order Recurrent Neural Networks
Dual Path Networks
DPN详解(Dual Path Networks)
解读Dual Path Networks(DPN,原创)
Dual Path Networks双分支网络
pytorch实现DPN 最详细的全面讲解

三、使用Pytorch实现

pytorch

class Block(nn.Module):
    def __init__(self, in_channel, mid_channel, out_channel, dense_channel, stride, groups, is_shortcut=False):
        # in_channel,是输入通道数,mid_channel是中间经历的通道数,out_channels是经过一次板块之后的输出通道数。
        # dense_channels设置这个参数的原因就是一边进行着resnet方式的卷积运算,另一边也同时进行着dense的卷积计算,之后特征图融合形成新的特征图
        super(Block, self).__init__()
        self.is_shortcut = is_shortcut
        self.out_channel = out_channel
        self.conv1 = nn.Sequential(
            nn.Conv2d(in_channel, mid_channel, kernel_size=1, bias=False),
            nn.BatchNorm2d(mid_channel),
            nn.ReLU()
        )
        self.conv2 = nn.Sequential(
            nn.Conv2d(mid_channel, mid_channel, kernel_size=3, stride=stride, padding=1, groups=groups, bias=False),
            nn.BatchNorm2d(mid_channel),
            nn.ReLU()
        )
        self.conv3 = nn.Sequential(
            nn.Conv2d(mid_channel, out_channel+dense_channel, kernel_size=1, bias=False),
            nn.BatchNorm2d(out_channel+dense_channel)
        )
        if self.is_shortcut:
            self.shortcut = nn.Sequential(
                nn.Conv2d(in_channel, out_channel+dense_channel, kernel_size=3, padding=1, stride=stride, bias=False),
                nn.BatchNorm2d(out_channel+dense_channel)
            )
        self.relu = nn.ReLU(inplace=True)
    
    def forward(self, x):
        a = x
        x = self.conv1(x)
        x = self.conv2(x)
        x = self.conv3(x)
        if self.is_shortcut:
            a = self.shortcut(a)
        d = self.out_channel
        x = torch.cat([a[:,:d,:,:] + x[:,:d,:,:], a[:,d:,:,:], x[:,d:,:,:]], dim=1)
        x = self.relu(x)
        return x


class DPN(nn.Module):
    def __init__(self, cfg):
        super(DPN, self).__init__()
        self.group = cfg['group']
        self.in_channel = cfg['in_channel']
        mid_channels = cfg['mid_channels']
        out_channels = cfg['out_channels']
        dense_channels = cfg['dense_channels']
        num = cfg['num']
        self.conv1 = nn.Sequential(
            nn.Conv2d(3, self.in_channel, 7, stride=2, padding=3, bias=False, padding_mode='zeros'),
            nn.BatchNorm2d(self.in_channel),
            nn.ReLU(),
            nn.MaxPool2d(kernel_size=3, stride=2, padding=0)
        )
        self.conv2 = self._make_layers(mid_channels[0], out_channels[0], dense_channels[0], num[0], stride=1)
        self.conv3 = self._make_layers(mid_channels[1], out_channels[1], dense_channels[1], num[1], stride=2)
        self.conv4 = self._make_layers(mid_channels[2], out_channels[2], dense_channels[2], num[2], stride=2)
        self.conv5 = self._make_layers(mid_channels[3], out_channels[3], dense_channels[3], num[3], stride=2)
        self.pool = nn.AdaptiveAvgPool2d((1, 1))
        self.fc = nn.Linear(cfg['out_channels'][3] + (num[3]+1) * cfg['dense_channels'][3], cfg['classes']) # fc层需要计算
    
    def _make_layers(self, mid_channel, out_channel, dense_channel, num, stride=2):
        layers = []
        layers.append(Block(self.in_channel, mid_channel, out_channel, dense_channel, stride=stride, groups=self.group, is_shortcut=True))
        # block_1里面is_shortcut=True就是resnet中的shortcut连接,将浅层的特征进行一次卷积之后与进行三次卷积的特征图相加
        # 后面几次相同的板块is_shortcut=False简单的理解就是一个多次重复的板块,第一次利用就可以满足浅层特征的利用,后面重复的不在需要
        self.in_channel = out_channel + dense_channel*2
        # 由于里面包含dense这种一直在叠加的特征图计算,
        # 所以第一次是2倍的dense_channel,后面每次一都会多出1倍,所以有(i+2)*dense_channel
        for i in range(1, num):
            layers.append(Block(self.in_channel, mid_channel, out_channel, dense_channel, stride=1, groups=self.group))
            self.in_channel = self.in_channel + dense_channel
            #self.in_channel = out_channel + (i+2)*dense_channel
        return nn.Sequential(*layers)
    
    def forward(self, x):
        x = self.conv1(x)
        x = self.conv2(x)
        x = self.conv3(x)
        x = self.conv4(x)
        x = self.conv5(x)
        x = self.pool(x)
        x = torch.flatten(x, start_dim=1)
        x = self.fc(x)
        return x


def DPN92(n_class=10):
    cfg = {
   
        'group': 32,
        'in_channel': 64,
        'mid_channels': (96, 192, 384, 768),
        'out_channels': (256, 512, 1024, 2048),
        'dense_channels': (16, 32, 24, 128),
        'num': (3, 4, 20, 3),
        'classes': (n_class)
    }
    return DPN(cfg)


def DPN98(n_class=10):
    cfg = {
   
        'group': 40,
        'in_channel': 96,
        'mid_channels': (160, 320, 640, 1280),
        'out_channels': (256, 512, 1024, 2048),
        'dense_channels': (16, 32, 32, 128),
        'num': (3, 6, 20, 3),
        'classes': (n_class)
    }
    return DPN(cfg)

四、打印模型查看&运行

1.模型打印

----------------------------------------------------------------
        Layer (type)               Output Shape         Param #
================================================================
            Conv2d-1         [-1, 64, 112, 112]           9,408
       BatchNorm2d-2         [-1, 64, 112, 112]             128
              ReLU-3         [-1, 64, 112, 112]               0
         MaxPool2d-4           [-1, 64, 55, 55]               0
            Conv2d-5           [-1, 96, 55, 55]           6,144
       BatchNorm2d-6           [-1, 96, 55, 55]             192
              ReLU-7           [-1, 96, 55, 55]               0
            Conv2d-8           [-1, 96, 55, 55]           2,592
       BatchNorm2d-9           [-1, 96, 55, 55]             192
             ReLU-10           [-1, 96, 55, 55]               0
           Conv2d-11          [-1, 272, 55, 55]          26,112
      BatchNorm2d-12          [-1, 272, 55, 55]             544
           Conv2d-13          [-1, 272, 55, 55]         156,672
      BatchNorm2d-14          [-1, 272, 55, 55]             544
             ReLU-15          [-1, 288, 55, 55]               0
            Block-16          [-1, 288, 55, 55]               0
           Conv2d-17           [-1, 96, 55, 55]          27,648
      BatchNorm2d-18           [-1, 96, 55, 55]             192
             ReLU-19           [-1, 96, 55, 55]               0
           Conv2d-20           [-1, 96, 55, 55]           2,592
      BatchNorm2d-21           [-1, 96, 55, 55]             192
             ReLU-22           [-1, 96, 55, 55]               0
           Conv2d-23          [-1, 272, 55, 55]          26,112
      BatchNorm2d-24          [-1, 272, 55, 55]             544
             ReLU-25          [-1, 304, 55, 55]               0
            Block-26          [-1, 304, 55, 55]               0
           Conv2d-27           [-1, 96, 55, 55]          29,184
      BatchNorm2d-28           [-1, 96, 55, 55]             192
             ReLU-29           [-1, 96, 55, 55]               0
           Conv2d-30           [-1, 96, 55, 55]           2,592
      BatchNorm2d-31           [-1, 96, 55, 55]             192
             ReLU-32           [-1, 96, 55, 55]               0
           Conv2d-33          [-1, 272, 55, 55]          26,112
      BatchNorm2d-34          [-1, 272, 55, 55]             544
             ReLU-35          [-1, 320, 55, 55]               0
            Block-36          [-1, 320, 55, 55]               0
           Conv2d-37          [-1, 192, 55, 55]          61,440
      BatchNorm2d-38          [-1, 192, 55, 55]             384
             ReLU-39          [-1, 192, 55, 55]               0
           Conv2d-40          [-1, 192, 28, 28]          10,368
      BatchNorm2d-41          [-1, 192, 28, 28]             384
             ReLU-42          [-1, 192, 28, 28]               0
           Conv2d-43          [-1, 544, 28, 28]         104,448
      BatchNorm2d-44          [-1, 544, 28, 28]           1,088
           Conv2d-45          [-1, 544, 28, 28]       1,566,720
      BatchNorm2d-46          [-1, 544, 28, 28]           1,088
             ReLU-47          [-1, 576, 28, 28]               0
            Block-48          [-1, 576, 28, 28]               0
           Conv2d-49          [-1, 192, 28, 28]         110,592
      BatchNorm2d-50          [-1, 192, 28, 28]             384
             ReLU-51          [-1, 192, 28, 28]               0
           Conv2d-52          [-1, 192, 28, 28]          10,368
      BatchNorm2d-53          [-1, 192, 28, 28]             384
             ReLU-54          [-1, 192, 28, 28]               0
           Conv2d-55          [-1, 544, 28, 28]         104,448
      BatchNorm2d-56          [-1, 544, 28, 28]           1,088
             ReLU-57          [-1, 608, 28, 28]               0
            Block-58          [-1, 608, 28, 28]               0
           Conv2d-59          [-1, 192, 28, 28]         116,736
      BatchNorm2d-60          [-1, 192, 28, 28]             384
             ReLU-61          [-1, 192, 28, 28]               0
           Conv2d-62          [-1, 192, 28, 28]          10,368
      BatchNorm2d-63          [-1, 192, 28, 28]             384
             ReLU-64          [-1, 192, 28, 28]               0
           Conv2d-65          [-1, 544, 28, 28]         104,448
      BatchNorm2d-66          [-1, 544, 28, 28]           1,088
             ReLU-67          [-1, 640, 28, 28]               0
            Block-68          [-1, 640, 28, 28]               0
           Conv2d-69          [-1, 192, 28, 28]         122,880
      BatchNorm2d-70          [-1, 192, 28, 28]             384
             ReLU-71          [-1, 192, 28, 28]               0
           Conv2d-72          [-1, 192, 28, 28]          10,368
      BatchNorm2d-73          [-1, 192, 28, 28]             384
             ReLU-74          [-1, 192, 28, 28]               0
           Conv2d-75          [-1, 544, 28, 28]         104,448
      BatchNorm2d-76          [-1, 544, 28, 28]           1,088
             ReLU-77          [
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