YOLOv9改进策略：注意力机制 |通道注意力和空间注意力CBAM

💡💡💡本文改进内容：通道注意力和空间注意力CBAM，全新注意力GAM：超越CBAM，不计成本提高精度

改进结构图如下：

YOLOv9魔术师专栏

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包含注意力机制魔改、卷积魔改、检测头创新、损失&IOU优化、block优化&多层特征融合、轻量级网络设计、24年最新顶会改进思路、原创自研paper级创新等

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YOLOv9魔改：注意力机制、检测头、blcok魔改、自研原创等

YOLOv9魔术师

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1.YOLOv9原理介绍

论文： 2402.13616.pdf (arxiv.org)

代码：GitHub - WongKinYiu/yolov9: Implementation of paper - YOLOv9: Learning What You Want to Learn Using Programmable Gradient Information摘要： 如今的深度学习方法重点关注如何设计最合适的目标函数，从而使得模型的预测结果能够最接近真实情况。同时，必须设计一个适当的架构，可以帮助获取足够的信息进行预测。然而，现有方法忽略了一个事实，即当输入数据经过逐层特征提取和空间变换时，大量信息将会丢失。因此，YOLOv9 深入研究了数据通过深度网络传输时数据丢失的重要问题，即信息瓶颈和可逆函数。作者提出了可编程梯度信息（programmable gradient information，PGI）的概念，来应对深度网络实现多个目标所需要的各种变化。PGI 可以为目标任务计算目标函数提供完整的输入信息，从而获得可靠的梯度信息来更新网络权值。此外，研究者基于梯度路径规划设计了一种新的轻量级网络架构，即通用高效层聚合网络（Generalized Efficient Layer Aggregation Network，GELAN）。该架构证实了 PGI 可以在轻量级模型上取得优异的结果。研究者在基于 MS COCO 数据集的目标检测任务上验证所提出的 GELAN 和 PGI。结果表明，与其他 SOTA 方法相比，GELAN 仅使用传统卷积算子即可实现更好的参数利用率。对于 PGI 而言，它的适用性很强，可用于从轻型到大型的各种模型。我们可以用它来获取完整的信息，从而使从头开始训练的模型能够比使用大型数据集预训练的 SOTA 模型获得更好的结果。对比结果如图1所示。

YOLOv9框架图

2.计算机视觉中的注意力机制

一般来说，注意力机制通常被分为以下基本四大类：

通道注意力 Channel Attention

空间注意力机制 Spatial Attention

时间注意力机制 Temporal Attention

分支注意力机制 Branch Attention

2.1.CBAM：通道注意力和空间注意力的集成者

轻量级的卷积注意力模块，它结合了通道和空间的注意力机制模块

论文题目：《CBAM: Convolutional Block Attention Module》
论文地址： https://arxiv.org/pdf/1807.06521.pdf

上图可以看到，CBAM包含CAM（Channel Attention Module）和SAM（Spartial Attention Module）两个子模块，分别进行通道和空间上的Attention。这样不只能够节约参数和计算力，并且保证了其能够做为即插即用的模块集成到现有的网络架构中去。

2.2 GAM：Global Attention Mechanism

超越CBAM，全新注意力GAM：不计成本提高精度！
论文题目：Global Attention Mechanism: Retain Information to Enhance Channel-Spatial Interactions
论文地址：https://paperswithcode.com/paper/global-attention-mechanism-retain-information

从整体上可以看出，GAM和CBAM注意力机制还是比较相似的，同样是使用了通道注意力机制和空间注意力机制。但是不同的是对通道注意力和空间注意力的处理。

3.CBAM、GAM加入到YOLOv9

3.1新建py文件，路径为models/attention/attention.py

import torch
from torch import nn
from torch.nn import init
import torch.nn.functional as F


class ChannelAttention(nn.Module):
    # Channel-attention module https://github.com/open-mmlab/mmdetection/tree/v3.0.0rc1/configs/rtmdet
    def __init__(self, channels: int) -> None:
        super().__init__()
        self.pool = nn.AdaptiveAvgPool2d(1)
        self.fc = nn.Conv2d(channels, channels, 1, 1, 0, bias=True)
        self.act = nn.Sigmoid()

    def forward(self, x: torch.Tensor) -> torch.Tensor:
        return x * self.act(self.fc(self.pool(x)))


class SpatialAttention(nn.Module):
    # Spatial-attention module
    def __init__(self, kernel_size=7):
        super().__init__()
        assert kernel_size in (3, 7), 'kernel size must be 3 or 7'
        padding = 3 if kernel_size == 7 else 1
        self.cv1 = nn.Conv2d(2, 1, kernel_size, padding=padding, bias=False)
        self.act = nn.Sigmoid()

    def forward(self, x):
        return x * self.act(self.cv1(torch.cat([torch.mean(x, 1, keepdim=True), torch.max(x, 1, keepdim=True)[0]], 1)))


class CBAM(nn.Module):
    # Convolutional Block Attention Module
    def __init__(self, c1,c2, kernel_size=7):  # ch_in, kernels
        super().__init__()
        self.channel_attention = ChannelAttention(c2)
        self.spatial_attention = SpatialAttention(kernel_size)

    def forward(self, x):
        return self.spatial_attention(self.channel_attention(x))


def channel_shuffle(x, groups=2):  ##shuffle channel
    # RESHAPE----->transpose------->Flatten
    B, C, H, W = x.size()
    out = x.view(B, groups, C // groups, H, W).permute(0, 2, 1, 3, 4).contiguous()
    out = out.view(B, C, H, W)
    return out


class GAM_Attention(nn.Module):
    # https://paperswithcode.com/paper/global-attention-mechanism-retain-information
    def __init__(self, c1, c2, group=True, rate=4):
        super(GAM_Attention, self).__init__()

        self.channel_attention = nn.Sequential(
            nn.Linear(c1, int(c1 / rate)),
            nn.ReLU(inplace=True),
            nn.Linear(int(c1 / rate), c1)
        )

        self.spatial_attention = nn.Sequential(

            nn.Conv2d(c1, c1 // rate, kernel_size=7, padding=3, groups=rate) if group else nn.Conv2d(c1, int(c1 / rate),
                                                                                                     kernel_size=7,
                                                                                                     padding=3),
            nn.BatchNorm2d(int(c1 / rate)),
            nn.ReLU(inplace=True),
            nn.Conv2d(c1 // rate, c2, kernel_size=7, padding=3, groups=rate) if group else nn.Conv2d(int(c1 / rate), c2,
                                                                                                     kernel_size=7,
                                                                                                     padding=3),
            nn.BatchNorm2d(c2)
        )

    def forward(self, x):
        b, c, h, w = x.shape
        x_permute = x.permute(0, 2, 3, 1).view(b, -1, c)
        x_att_permute = self.channel_attention(x_permute).view(b, h, w, c)
        x_channel_att = x_att_permute.permute(0, 3, 1, 2)
        # x_channel_att=channel_shuffle(x_channel_att,4) #last shuffle
        x = x * x_channel_att

        x_spatial_att = self.spatial_attention(x).sigmoid()
        x_spatial_att = channel_shuffle(x_spatial_att, 4)  # last shuffle
        out = x * x_spatial_att
        # out=channel_shuffle(out,4) #last shuffle
        return out

3.2修改yolo.py

1)首先进行引用

from models.attention.attention import *

2）修改def parse_model(d, ch): # model_dict, input_channels(3)

在源码基础上加入CBAM,GAM_Attention

        elif m is nn.BatchNorm2d:
            args = [ch[f]]
        ###attention #####
        elif m in {EMA_attention, CoordAtt,CBAM,GAM_Attention}:
            c2 = ch[f]
            args = [c2, *args]

        ###attention #####

3.3 yolov9-c-CBAM.yaml

# YOLOv9
 
# parameters
nc: 80  # number of classes
depth_multiple: 1.0  # model depth multiple
width_multiple: 1.0  # layer channel multiple
#activation: nn.LeakyReLU(0.1)
#activation: nn.ReLU()
 
# anchors
anchors: 3
 
# YOLOv9 backbone
backbone:
  [
   [-1, 1, Silence, []],  
   
   # conv down
   [-1, 1, Conv, [64, 3, 2]],  # 1-P1/2
 
   # conv down
   [-1, 1, Conv, [128, 3, 2]],  # 2-P2/4
 
   # elan-1 block
   [-1, 1, RepNCSPELAN4, [256, 128, 64, 1]],  # 3
 
   # avg-conv down
   [-1, 1, ADown, [256]],  # 4-P3/8
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 256, 128, 1]],  # 5
 
   # avg-conv down
   [-1, 1, ADown, [512]],  # 6-P4/16
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 7
 
   # avg-conv down
   [-1, 1, ADown, [512]],  # 8-P5/32
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 9
   
   [-1, 1, CBAM, [512]],  # 10
  ]
 
# YOLOv9 head
head:
  [
   # elan-spp block
   [-1, 1, SPPELAN, [512, 256]],  # 11
 
   # up-concat merge
   [-1, 1, nn.Upsample, [None, 2, 'nearest']],
   [[-1, 7], 1, Concat, [1]],  # cat backbone P4
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 14
 
   # up-concat merge
   [-1, 1, nn.Upsample, [None, 2, 'nearest']],
   [[-1, 5], 1, Concat, [1]],  # cat backbone P3
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [256, 256, 128, 1]],  # 17 (P3/8-small)
 
   # avg-conv-down merge
   [-1, 1, ADown, [256]],
   [[-1, 14], 1, Concat, [1]],  # cat head P4
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 20 (P4/16-medium)
 
   # avg-conv-down merge
   [-1, 1, ADown, [512]],
   [[-1, 11], 1, Concat, [1]],  # cat head P5
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 23 (P5/32-large)
   
   
   # multi-level reversible auxiliary branch
   
   # routing
   [5, 1, CBLinear, [[256]]], # 24
   [7, 1, CBLinear, [[256, 512]]], # 25
   [9, 1, CBLinear, [[256, 512, 512]]], # 26
   
   # conv down
   [0, 1, Conv, [64, 3, 2]],  # 27-P1/2
 
   # conv down
   [-1, 1, Conv, [128, 3, 2]],  # 28-P2/4
 
   # elan-1 block
   [-1, 1, RepNCSPELAN4, [256, 128, 64, 1]],  # 29
 
   # avg-conv down fuse
   [-1, 1, ADown, [256]],  # 30-P3/8
   [[24, 25, 26, -1], 1, CBFuse, [[0, 0, 0]]], # 31  
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 256, 128, 1]],  # 32
 
   # avg-conv down fuse
   [-1, 1, ADown, [512]],  # 33-P4/16
   [[25, 26, -1], 1, CBFuse, [[1, 1]]], # 34 
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 35
 
   # avg-conv down fuse
   [-1, 1, ADown, [512]],  # 36-P5/32
   [[26, -1], 1, CBFuse, [[2]]], # 37
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 38
   
   
   
   # detection head
 
   # detect
   [[32, 35, 38, 17, 20, 23], 1, DualDDetect, [nc]],  # DualDDetect(A3, A4, A5, P3, P4, P5)
  ]

3.4 yolov9-c-GAM.yaml

# YOLOv9
 
# parameters
nc: 80  # number of classes
depth_multiple: 1.0  # model depth multiple
width_multiple: 1.0  # layer channel multiple
#activation: nn.LeakyReLU(0.1)
#activation: nn.ReLU()
 
# anchors
anchors: 3
 
# YOLOv9 backbone
backbone:
  [
   [-1, 1, Silence, []],  
   
   # conv down
   [-1, 1, Conv, [64, 3, 2]],  # 1-P1/2
 
   # conv down
   [-1, 1, Conv, [128, 3, 2]],  # 2-P2/4
 
   # elan-1 block
   [-1, 1, RepNCSPELAN4, [256, 128, 64, 1]],  # 3
 
   # avg-conv down
   [-1, 1, ADown, [256]],  # 4-P3/8
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 256, 128, 1]],  # 5
 
   # avg-conv down
   [-1, 1, ADown, [512]],  # 6-P4/16
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 7
 
   # avg-conv down
   [-1, 1, ADown, [512]],  # 8-P5/32
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 9
   
   [-1, 1, GAM_Attention, [512]],  # 10
  ]
 
# YOLOv9 head
head:
  [
   # elan-spp block
   [-1, 1, SPPELAN, [512, 256]],  # 11
 
   # up-concat merge
   [-1, 1, nn.Upsample, [None, 2, 'nearest']],
   [[-1, 7], 1, Concat, [1]],  # cat backbone P4
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 14
 
   # up-concat merge
   [-1, 1, nn.Upsample, [None, 2, 'nearest']],
   [[-1, 5], 1, Concat, [1]],  # cat backbone P3
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [256, 256, 128, 1]],  # 17 (P3/8-small)
 
   # avg-conv-down merge
   [-1, 1, ADown, [256]],
   [[-1, 14], 1, Concat, [1]],  # cat head P4
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 20 (P4/16-medium)
 
   # avg-conv-down merge
   [-1, 1, ADown, [512]],
   [[-1, 11], 1, Concat, [1]],  # cat head P5
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 23 (P5/32-large)
   
   
   # multi-level reversible auxiliary branch
   
   # routing
   [5, 1, CBLinear, [[256]]], # 24
   [7, 1, CBLinear, [[256, 512]]], # 25
   [9, 1, CBLinear, [[256, 512, 512]]], # 26
   
   # conv down
   [0, 1, Conv, [64, 3, 2]],  # 27-P1/2
 
   # conv down
   [-1, 1, Conv, [128, 3, 2]],  # 28-P2/4
 
   # elan-1 block
   [-1, 1, RepNCSPELAN4, [256, 128, 64, 1]],  # 29
 
   # avg-conv down fuse
   [-1, 1, ADown, [256]],  # 30-P3/8
   [[24, 25, 26, -1], 1, CBFuse, [[0, 0, 0]]], # 31  
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 256, 128, 1]],  # 32
 
   # avg-conv down fuse
   [-1, 1, ADown, [512]],  # 33-P4/16
   [[25, 26, -1], 1, CBFuse, [[1, 1]]], # 34 
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 35
 
   # avg-conv down fuse
   [-1, 1, ADown, [512]],  # 36-P5/32
   [[26, -1], 1, CBFuse, [[2]]], # 37
 
   # elan-2 block
   [-1, 1, RepNCSPELAN4, [512, 512, 256, 1]],  # 38
   
   
   
   # detection head
 
   # detect
   [[32, 35, 38, 17, 20, 23], 1, DualDDetect, [nc]],  # DualDDetect(A3, A4, A5, P3, P4, P5)
  ]