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.Yolov5加入CBAM、GAM
2.1 CBAM加入**
common.py
**中
class ChannelAttentionModule(nn.Module):
def __init__(self, c1, reduction=16,light=False):
super(ChannelAttentionModule, self).__init__()
mid_channel = c1 // reduction
self.light=light
self.avg_pool = nn.AdaptiveAvgPool2d(1)
if self.light:
self.max_pool = nn.AdaptiveMaxPool2d(1)
self.shared_MLP = nn.Sequential(
nn.Linear(in_features=c1, out_features=mid_channel),
nn.LeakyReLU(0.1, inplace=True),
nn.Linear(in_features=mid_channel, out_features=c1)
)
else:
self.shared_MLP = nn.Conv2d(c1, c1, 1, 1, 0, bias=True)
self.act = nn.Sigmoid()
def forward(self, x):
if self.light:
avgout = self.shared_MLP(self.avg_pool(x).view(x.size(0),-1)).unsqueeze(2).unsqueeze(3)
maxout = self.shared_MLP(self.max_pool(x).view(x.size(0),-1)).unsqueeze(2).unsqueeze(3)
fc_out=(avgout + maxout)
else:
fc_out=(self.shared_MLP(self.avg_pool(x)))
return x * self.act(fc_out)
class SpatialAttentionModule(nn.Module): ##update:coding-style FOR LIGHTING
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):
def __init__(self, c1,c2,k=7):
super().__init__()
self.channel_attention = ChannelAttentionModule(c1)
self.spatial_attention = SpatialAttentionModule(k)
def forward(self, x):
return self.spatial_attention(self.channel_attention(x))
2.2 GAM加入**
common.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
2.4 GAM加入**
common.py
中加入
common.py
**中
class ResBlock_CBAM(nn.Module):
def __init__(self, in_places, places, stride=1, downsampling=False, expansion=4):
super(ResBlock_CBAM, self).__init__()
self.expansion = expansion
self.downsampling = downsampling
self.bottleneck = nn.Sequential(
nn.Conv2d(in_channels=in_places, out_channels=places, kernel_size=1, stride=1, bias=False),
nn.BatchNorm2d(places),
nn.LeakyReLU(0.1, inplace=True),
nn.Conv2d(in_channels=places, out_channels=places, kernel_size=3, stride=stride, padding=1, bias=False),
nn.BatchNorm2d(places),
nn.LeakyReLU(0.1, inplace=True),
nn.Conv2d(in_channels=places, out_channels=places * self.expansion, kernel_size=1, stride=1,
bias=False),
nn.BatchNorm2d(places * self.expansion),
)
self.cbam = CBAM(c1=places * self.expansion, c2=places * self.expansion, )
if self.downsampling:
self.downsample = nn.Sequential(
nn.Conv2d(in_channels=in_places, out_channels=places * self.expansion, kernel_size=1, stride=stride,
bias=False),
nn.BatchNorm2d(places * self.expansion)
)
self.relu = nn.ReLU(inplace=True)
def forward(self, x):
residual = x
out = self.bottleneck(x)
out = self.cbam(out)
if self.downsampling:
residual = self.downsample(x)
out += residual
out = self.relu(out)
return out
2.3 CBAM、GAM加入yolo**
.py
**中
if m in {
Conv, GhostConv, Bottleneck, GhostBottleneck, SPP, SPPF, DWConv, MixConv2d, Focus, CrossConv,
BottleneckCSP, C3, C3TR, C3SPP, C3Ghost, nn.ConvTranspose2d, DWConvTranspose2d, C3x, C2f,CBAM,ResBlock_CBAM,GAM_Attention}:
2.4 CBAM、GAM修改对应yaml
2.4.1 修改 yolov5s_cbam.yaml
# parameters
nc: 10 # number of classes
depth_multiple: 0.33 # model depth multiple
width_multiple: 0.50 # layer channel multiple
# anchors
anchors:
#- [5,6, 7,9, 12,10] # P2/4
- [10,13, 16,30, 33,23] # P3/8
- [30,61, 62,45, 59,119] # P4/16
- [116,90, 156,198, 373,326] # P5/32
# YOLOv5 backbone
backbone:
# [from, number, module, args] # [c=channels,module,kernlsize,strides]
[[-1, 1, Conv, [64, 6, 2, 2]], # 0-P1/2 [c=3,64*0.5=32,3]
[-1, 1, Conv, [128, 3, 2]], # 1-P2/4
[-1, 3, C3, [128]],
[-1, 1, Conv, [256, 3, 2]], # 3-P3/8
[-1, 6, C3, [256]],
[-1, 1, Conv, [512, 3, 2]], # 5-P4/16
[-1, 9, C3, [512]],
[-1, 1, Conv, [1024, 3, 2]], # 7-P5/32
[-1, 3, C3, [1024]],
[-1, 1, CBAM, [1024,7]], #9
[-1, 1, SPPF, [1024,5]], #10
]
# YOLOv5 head
head:
[[-1, 1, Conv, [512, 1, 1]],
[-1, 1, nn.Upsample, [None, 2, 'nearest']],
[[-1, 6], 1, Concat, [1]], # cat backbone P4
[-1, 3, C3, [512, False]], # 14
[-1, 1, Conv, [256, 1, 1]],
[-1, 1, nn.Upsample, [None, 2, 'nearest']],
[[-1, 4], 1, Concat, [1]], # cat backbone P3
[-1, 3, C3, [256, False]], # 18 (P3/8-small)
[-1, 1, CBAM, [256,7]], #19
[-1, 1, Conv, [256, 3, 2]],
[[-1, 15], 1, Concat, [1]], # cat head P4
[-1, 3, C3, [512, False]], # 22 (P4/16-medium) [256, 256, 1, False]
[-1, 1, CBAM, [512,7]],
[-1, 1, Conv, [512, 3, 2]], #[256, 256, 3, 2]
[[-1, 11], 1, Concat, [1]], # cat head P5
[-1, 3, C3, [1024, False]], # 25 (P5/32-large) [512, 512, 1, False]
[-1, 1, CBAM, [1024,7]],
[[19, 23, 27], 1, Detect, [nc, anchors]], # Detect(P3, P4, P5)
]
2.4.2 修改 yolov5s_gam.yaml
# parameters
nc: 1 # number of classes
depth_multiple: 0.33 # model depth multiple
width_multiple: 0.50 # layer channel multiple
# anchors
anchors:
#- [5,6, 7,9, 12,10] # P2/4
- [10,13, 16,30, 33,23] # P3/8
- [30,61, 62,45, 59,119] # P4/16
- [116,90, 156,198, 373,326] # P5/32
# YOLOv5 backbone
backbone:
# [from, number, module, args] # [c=channels,module,kernlsize,strides]
[[-1, 1, Conv, [64, 6, 2, 2]], # 0-P1/2 [c=3,64*0.5=32,3]
[-1, 1, Conv, [128, 3, 2]], # 1-P2/4
[-1, 3, C3, [128]],
[-1, 1, Conv, [256, 3, 2]], # 3-P3/8
[-1, 6, C3, [256]],
[-1, 1, Conv, [512, 3, 2]], # 5-P4/16
[-1, 9, C3, [512]],
[-1, 1, Conv, [1024, 3, 2]], # 7-P5/32
[-1, 3, C3, [1024]],
[-1, 1, GAM_Attention, [1024,1024]], #9
[-1, 1, SPPF, [1024,5]], #10
]
# YOLOv5 head
head:
[[-1, 1, Conv, [512, 1, 1]],
[-1, 1, nn.Upsample, [None, 2, 'nearest']],
[[-1, 6], 1, Concat, [1]], # cat backbone P4
[-1, 3, C3, [512, False]], # 14
[-1, 1, Conv, [256, 1, 1]],
[-1, 1, nn.Upsample, [None, 2, 'nearest']],
[[-1, 4], 1, Concat, [1]], # cat backbone P3
[-1, 3, C3, [256, False]], # 18 (P3/8-small)
[-1, 1, GAM_Attention, [256,256]], #19
[-1, 1, Conv, [256, 3, 2]],
[[-1, 15], 1, Concat, [1]], # cat head P4
[-1, 3, C3, [512, False]], # 22 (P4/16-medium) [256, 256, 1, False]
[-1, 1, GAM_Attention, [512,512]],
[-1, 1, Conv, [512, 3, 2]], #[256, 256, 3, 2]
[[-1, 11], 1, Concat, [1]], # cat head P5
[-1, 3, C3, [1024, False]], # 25 (P5/32-large) [512, 512, 1, False]
[-1, 1, GAM_Attention, [1024,1024]], #
[[19, 23, 27], 1, Detect, [nc, anchors]], # Detect(P3, P4, P5)
]
版权归原作者 AI&CV 所有, 如有侵权,请联系我们删除。