专栏介绍：YOLOv9改进系列 | 包含深度学习最新创新，主力高效涨点！！！
一、论文摘要
由于内存和计算资源有限，在嵌入式设备上部署卷积神经网络是困难的。特征图中的冗余是那些成功的细胞神经网络的一个重要特征，但在神经结构设计中很少进行研究。本文提出了一种新的Ghost模块，通过少量的计算生成更多的特征图。基于一组内在特征图，我们以低廉的成本应用一系列线性变换来生成许多重影特征图，这些重影特征图可充分揭示内在特征背后的信息。所提出的Ghost模块可以作为即插即用组件来升级现有的卷积神经网络。Ghost瓶颈被设计为堆叠Ghost模块，然后可以轻松地建立轻量级GhostNet。
适用检测目标： 轻量化或移动端部署
二、Ghost Conv模块详解
《GhostNet: More Features from Cheap Operations》
论文地址： https://arxiv.org/abs/1911.11907
2.1 模块简介
Ghost Conv的主要思想： 通过一系列线性变换，以很小的计算量从原始特征发掘所需信息的“Ghost”特征图（Ghost feature maps）
总结： 一种类似残差的模块
Ghost Conv模块的原理图
三、Ghost Conv模块使用教程
3.1 Ghost Conv模块的代码
class GhostConv(nn.Module):
"""Ghost Convolution https://github.com/huawei-noah/ghostnet."""
def __init__(self, c1, c2, k=1, s=1, g=1, act=True):
"""Initializes the GhostConv object with input channels, output channels, kernel size, stride, groups and
activation.
"""
super().__init__()
c_ = c2 // 2 # hidden channels
self.cv1 = Conv(c1, c_, k, s, None, g, act=act)
self.cv2 = Conv(c_, c_, 5, 1, None, c_, act=act)
def forward(self, x):
"""Forward propagation through a Ghost Bottleneck layer with skip connection."""
y = self.cv1(x)
return torch.cat((y, self.cv2(y)), 1)
3.2 在YOlO v9中的添加教程
阅读YOLOv9添加模块教程或使用下文操作
1. 将YOLOv9工程中models下common.py文件中增加模块的代码。
2. 将YOLOv9工程中models下yolo.py文件中的第718行（可能因版本变化而变化）增加以下代码。
RepNCSPELAN4, SPPELAN, GhostConv}:
3.3 运行配置文件
# YOLOv9
# Powered bu https://blog.csdn.net/StopAndGoyyy
# parameters
nc: 80 # number of classes
depth_multiple: 1 # model depth multiple
width_multiple: 1 # 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
]
# YOLOv9 head
head:
[
# elan-spp block
[-1, 1, SPPELAN, [512, 256]], # 10
# 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]], # 13
# 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]], # 16 (P3/8-small)
# avg-conv-down merge
[-1, 1, ADown, [256]],
[[-1, 13], 1, Concat, [1]], # cat head P4
# elan-2 block
[-1, 1, RepNCSPELAN4, [512, 512, 256, 1]], # 19 (P4/16-medium)
# avg-conv-down merge
[-1, 1, ADown, [512]],
[[-1, 10], 1, Concat, [1]], # cat head P5
# elan-2 block
[-1, 1, RepNCSPELAN4, [512, 512, 256, 1]], # 22 (P5/32-large)
# multi-level reversible auxiliary branch
# routing
[5, 1, CBLinear, [[256]]], # 23
[7, 1, CBLinear, [[256, 512]]], # 24
[9, 1, CBLinear, [[256, 512, 512]]], # 25
# conv down
[0, 1, Conv, [64, 3, 2]], # 26-P1/2
# conv down
[-1, 1, Conv, [128, 3, 2]], # 27-P2/4
# elan-1 block
[-1, 1, RepNCSPELAN4, [256, 128, 64, 1]], # 28
# avg-conv down fuse
[-1, 1, ADown, [256]], # 29-P3/8
[[23, 24, 25, -1], 1, CBFuse, [[0, 0, 0]]], # 30
# elan-2 block
[-1, 1, RepNCSPELAN4, [512, 256, 128, 1]], # 31
# avg-conv down fuse
[-1, 1, ADown, [512]], # 32-P4/16
[[24, 25, -1], 1, CBFuse, [[1, 1]]], # 33
# elan-2 block
[-1, 1, RepNCSPELAN4, [512, 512, 256, 1]], # 34
# avg-conv down fuse
[-1, 1, ADown, [512]], # 35-P5/32
[[25, -1], 1, CBFuse, [[2]]], # 36
# elan-2 block
[-1, 1, RepNCSPELAN4, [512, 512, 256, 1]], # 37
[-1, 1, GhostConv, [512, 3]], # 38
# detection head
# detect
[[31, 34, 38, 16, 19, 22], 1, DualDDetect, [nc]], # DualDDetect(A3, A4, A5, P3, P4, P5)
]
3.4 训练过程
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