1.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
1.1.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。
1.2 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。
1.3 ResBlock_CBAM
CBAM结构其实就是将通道注意力信息核空间注意力信息在一个block结构中进行运用。
在resnet中实现cbam:即在原始block和残差结构连接前,依次通过channel attention和spatial attention即可。
1.4性能评价
2.Yolov8加入CBAM、GAM
2.1 CBAM加入modules.py中(相当于yolov5中的common.py)
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, kernel_size=7): # ch_in, kernels
super().__init__()
self.channel_attention = ChannelAttention(c1)
self.spatial_attention = SpatialAttention(kernel_size)
def forward(self, x):
return self.spatial_attention(self.channel_attention(x))
2.2 GAM_Attention加入modules.py中:
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
2.3 CBAM、GAM_Attention、ResBlock_CBAM加入tasks.py中(相当于yolov5中的yolo.py
)
from ultralytics.nn.modules import (C1, C2, C3, C3TR, SPP, SPPF, Bottleneck, BottleneckCSP, C2f, C3Ghost, C3x, Classify,
Concat, Conv, ConvTranspose, Detect, DWConv, DWConvTranspose2d, Ensemble, Focus,
GhostBottleneck, GhostConv, Segment,CBAM, GAM_Attention , ResBlock_CBAM)
def parse_model(d, ch, verbose=True):函数中
if m in (Classify, Conv, ConvTranspose, GhostConv, Bottleneck, GhostBottleneck, SPP, SPPF, DWConv, Focus,
BottleneckCSP, C1, C2, C2f, C3, C3TR, C3Ghost, nn.ConvTranspose2d, DWConvTranspose2d, C3x , CBAM , GAM_Attention ,ResBlock_CBAM):
2.4 CBAM、GAM修改对应yaml
2.4.1 CBAM加入yolov8
# Ultralytics YOLO 🚀, GPL-3.0 license
# YOLOv8 object detection model with P3-P5 outputs. For Usage examples see https://docs.ultralytics.com/tasks/detect
# Parameters
nc: 80 # number of classes
scales: # model compound scaling constants, i.e. 'model=yolov8n.yaml' will call yolov8.yaml with scale 'n'
# [depth, width, max_channels]
n: [0.33, 0.25, 1024] # YOLOv8n summary: 225 layers, 3157200 parameters, 3157184 gradients, 8.9 GFLOPs
s: [0.33, 0.50, 1024] # YOLOv8s summary: 225 layers, 11166560 parameters, 11166544 gradients, 28.8 GFLOPs
m: [0.67, 0.75, 768] # YOLOv8m summary: 295 layers, 25902640 parameters, 25902624 gradients, 79.3 GFLOPs
l: [1.00, 1.00, 512] # YOLOv8l summary: 365 layers, 43691520 parameters, 43691504 gradients, 165.7 GFLOPs
x: [1.00, 1.25, 512] # YOLOv8x summary: 365 layers, 68229648 parameters, 68229632 gradients, 258.5 GFLOPs
# YOLOv8.0n backbone
backbone:
# [from, repeats, module, args]
- [-1, 1, Conv, [64, 3, 2]] # 0-P1/2
- [-1, 1, Conv, [128, 3, 2]] # 1-P2/4
- [-1, 3, C2f, [128, True]]
- [-1, 1, Conv, [256, 3, 2]] # 3-P3/8
- [-1, 6, C2f, [256, True]]
- [-1, 1, Conv, [512, 3, 2]] # 5-P4/16
- [-1, 6, C2f, [512, True]]
- [-1, 1, Conv, [1024, 3, 2]] # 7-P5/32
- [-1, 3, C2f, [1024, True]]
- [-1, 1, SPPF, [1024, 5]] # 9
# YOLOv8.0n head
head:
- [-1, 1, nn.Upsample, [None, 2, 'nearest']]
- [[-1, 6], 1, Concat, [1]] # cat backbone P4
- [-1, 3, C2f, [512]] # 12
- [-1, 1, CBAM, [512]]
- [-1, 1, nn.Upsample, [None, 2, 'nearest']]
- [[-1, 4], 1, Concat, [1]] # cat backbone P3
- [-1, 3, C2f, [256]] # 16 (P3/8-small)
- [-1, 1, CBAM, [256]]
- [-1, 1, Conv, [256, 3, 2]]
- [[-1, 13], 1, Concat, [1]] # cat head P4
- [-1, 3, C2f, [512]] # 20 (P4/16-medium)
- [-1, 1, CBAM, [512]]
- [-1, 1, Conv, [512, 3, 2]]
- [[-1, 9], 1, Concat, [1]] # cat head P5
- [-1, 3, C2f, [1024]] # 24 (P5/32-large)
- [-1, 1, CBAM, [1024]]
- [[17, 21, 25], 1, Detect, [nc]] # Detect(P3, P4, P5)
2.4.2 GAM加入yolov8
# Ultralytics YOLO 🚀, GPL-3.0 license
# YOLOv8 object detection model with P3-P5 outputs. For Usage examples see https://docs.ultralytics.com/tasks/detect
# Parameters
nc: 80 # number of classes
scales: # model compound scaling constants, i.e. 'model=yolov8n.yaml' will call yolov8.yaml with scale 'n'
# [depth, width, max_channels]
n: [0.33, 0.25, 1024] # YOLOv8n summary: 225 layers, 3157200 parameters, 3157184 gradients, 8.9 GFLOPs
s: [0.33, 0.50, 1024] # YOLOv8s summary: 225 layers, 11166560 parameters, 11166544 gradients, 28.8 GFLOPs
m: [0.67, 0.75, 768] # YOLOv8m summary: 295 layers, 25902640 parameters, 25902624 gradients, 79.3 GFLOPs
l: [1.00, 1.00, 512] # YOLOv8l summary: 365 layers, 43691520 parameters, 43691504 gradients, 165.7 GFLOPs
x: [1.00, 1.25, 512] # YOLOv8x summary: 365 layers, 68229648 parameters, 68229632 gradients, 258.5 GFLOPs
# YOLOv8.0n backbone
backbone:
# [from, repeats, module, args]
- [-1, 1, Conv, [64, 3, 2]] # 0-P1/2
- [-1, 1, Conv, [128, 3, 2]] # 1-P2/4
- [-1, 3, C2f, [128, True]]
- [-1, 1, Conv, [256, 3, 2]] # 3-P3/8
- [-1, 6, C2f, [256, True]]
- [-1, 1, Conv, [512, 3, 2]] # 5-P4/16
- [-1, 6, C2f, [512, True]]
- [-1, 1, Conv, [1024, 3, 2]] # 7-P5/32
- [-1, 3, C2f, [1024, True]]
- [-1, 1, SPPF, [1024, 5]] # 9
# YOLOv8.0n head
head:
- [-1, 1, nn.Upsample, [None, 2, 'nearest']]
- [[-1, 6], 1, Concat, [1]] # cat backbone P4
- [-1, 3, C2f, [512]] # 12
- [-1, 1, GAM_Attention, [512,512]]
- [-1, 1, nn.Upsample, [None, 2, 'nearest']]
- [[-1, 4], 1, Concat, [1]] # cat backbone P3
- [-1, 3, C2f, [256]] # 16 (P3/8-small)
- [-1, 1, GAM_Attention, [256,256]]
- [-1, 1, Conv, [256, 3, 2]]
- [[-1, 13], 1, Concat, [1]] # cat head P4
- [-1, 3, C2f, [512]] # 20 (P4/16-medium)
- [-1, 1, GAM_Attention, [512,512]]
- [-1, 1, Conv, [512, 3, 2]]
- [[-1, 9], 1, Concat, [1]] # cat head P5
- [-1, 3, C2f, [1024]] # 24 (P5/32-large)
- [-1, 1, GAM_Attention, [1024,1024]]
- [[17, 21, 25], 1, Detect, [nc]] # Detect(P3, P4, P5)
2.4.3 ResBlock_CBAM加入yolov8文章来源:https://www.toymoban.com/news/detail-442294.html
https://cv2023.blog.csdn.net/article/details/130974331文章来源地址https://www.toymoban.com/news/detail-442294.html
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