import typing as t import torch import torch.nn as nn from einops.einops import rearrange from mmengine.model import BaseModule __all__ = ['SCSA'] """SCSA：探索空间注意力和通道注意力之间的协同作用 通道和空间注意力分别在为各种下游视觉任务提取特征依赖性和空间结构关系方面带来了显着的改进。 虽然它们的结合更有利于发挥各自的优势，但通道和空间注意力之间的协同作用尚未得到充分探索，缺乏充分利用多语义信息的协同潜力来进行特征引导和缓解语义差异。 我们的研究试图在多个语义层面揭示空间和通道注意力之间的协同关系，提出了一种新颖的空间和通道协同注意力模块（SCSA）。我们的SCSA由两部分组成：可共享的多语义空间注意力（SMSA）和渐进式通道自注意力（PCSA）。 SMSA 集成多语义信息并利用渐进式压缩策略将判别性空间先验注入 PCSA 的通道自注意力中，有效地指导通道重新校准。此外，PCSA 中基于自注意力机制的稳健特征交互进一步缓解了 SMSA 中不同子特征之间多语义信息的差异。 我们在七个基准数据集上进行了广泛的实验，包括 ImageNet-1K 上的分类、MSCOCO 2017 上的对象检测、ADE20K 上的分割以及其他四个复杂场景检测数据集。我们的结果表明，我们提出的 SCSA 不仅超越了当前最先进的注意力机制， 而且在各种任务场景中表现出增强的泛化能力。 """ class SCSA(BaseModule): def __init__( self, dim: int, head_num: int, window_size: int = 7, group_kernel_sizes: t.List[int] = [3, 5, 7, 9], qkv_bias: bool = False, fuse_bn: bool = False, norm_cfg: t.Dict = dict(type='BN'), act_cfg: t.Dict = dict(type='ReLU'), down_sample_mode: str = 'avg_pool', attn_drop_ratio: float = 0., gate_layer: str = 'sigmoid', ): super(SCSA, self).__init__() self.dim = dim self.head_num = head_num self.head_dim = dim // head_num self.scaler = self.head_dim ** -0.5 self.group_kernel_sizes = group_kernel_sizes self.window_size = window_size self.qkv_bias = qkv_bias self.fuse_bn = fuse_bn self.down_sample_mode = down_sample_mode assert self.dim // 4, 'The dimension of input feature should be divisible by 4.' self.group_chans = group_chans = self.dim // 4 self.local_dwc = nn.Conv1d(group_chans, group_chans, kernel_size=group_kernel_sizes[0], padding=group_kernel_sizes[0] // 2, groups=group_chans) self.global_dwc_s = nn.Conv1d(group_chans, group_chans, kernel_size=group_kernel_sizes[1], padding=group_kernel_sizes[1] // 2, groups=group_chans) self.global_dwc_m = nn.Conv1d(group_chans, group_chans, kernel_size=group_kernel_sizes[2], padding=group_kernel_sizes[2] // 2, groups=group_chans) self.global_dwc_l = nn.Conv1d(group_chans, group_chans, kernel_size=group_kernel_sizes[3], padding=group_kernel_sizes[3] // 2, groups=group_chans) self.sa_gate = nn.Softmax(dim=2) if gate_layer == 'softmax' else nn.Sigmoid() self.norm_h = nn.GroupNorm(4, dim) self.norm_w = nn.GroupNorm(4, dim) self.conv_d = nn.Identity() self.norm = nn.GroupNorm(1, dim) self.q = nn.Conv2d(in_channels=dim, out_channels=dim, kernel_size=1, bias=qkv_bias, groups=dim) self.k = nn.Conv2d(in_channels=dim, out_channels=dim, kernel_size=1, bias=qkv_bias, groups=dim) self.v = nn.Conv2d(in_channels=dim, out_channels=dim, kernel_size=1, bias=qkv_bias, groups=dim) self.attn_drop = nn.Dropout(attn_drop_ratio) self.ca_gate = nn.Softmax(dim=1) if gate_layer == 'softmax' else nn.Sigmoid() if window_size == -1: self.down_func = nn.AdaptiveAvgPool2d((1, 1)) else: if down_sample_mode == 'recombination': self.down_func = self.space_to_chans # dimensionality reduction self.conv_d = nn.Conv2d(in_channels=dim * window_size ** 2, out_channels=dim, kernel_size=1, bias=False) elif down_sample_mode == 'avg_pool': self.down_func = nn.AvgPool2d(kernel_size=(window_size, window_size), stride=window_size) elif down_sample_mode == 'max_pool': self.down_func = nn.MaxPool2d(kernel_size=(window_size, window_size), stride=window_size) def forward(self, x: torch.Tensor) -> torch.Tensor: """ The dim of x is (B, C, H, W) """ # Spatial attention priority calculation b, c, h_, w_ = x.size() # (B, C, H) x_h = x.mean(dim=3) l_x_h, g_x_h_s, g_x_h_m, g_x_h_l = torch.split(x_h, self.group_chans, dim=1) # (B, C, W) x_w = x.mean(dim=2) l_x_w, g_x_w_s, g_x_w_m, g_x_w_l = torch.split(x_w, self.group_chans, dim=1) x_h_attn = self.sa_gate(self.norm_h(torch.cat(( self.local_dwc(l_x_h), self.global_dwc_s(g_x_h_s), self.global_dwc_m(g_x_h_m), self.global_dwc_l(g_x_h_l), ), dim=1))) x_h_attn = x_h_attn.view(b, c, h_, 1) x_w_attn = self.sa_gate(self.norm_w(torch.cat(( self.local_dwc(l_x_w), self.global_dwc_s(g_x_w_s), self.global_dwc_m(g_x_w_m), self.global_dwc_l(g_x_w_l) ), dim=1))) x_w_attn = x_w_attn.view(b, c, 1, w_) x = x * x_h_attn * x_w_attn # Channel attention based on self attention # reduce calculations y = self.down_func(x) y = self.conv_d(y) _, _, h_, w_ = y.size() # normalization first, then reshape -> (B, H, W, C) -> (B, C, H * W) and generate q, k and v y = self.norm(y) q = self.q(y) k = self.k(y) v = self.v(y) # (B, C, H, W) -> (B, head_num, head_dim, N) q = rearrange(q, 'b (head_num head_dim) h w -> b head_num head_dim (h w)', head_num=int(self.head_num), head_dim=int(self.head_dim)) k = rearrange(k, 'b (head_num head_dim) h w -> b head_num head_dim (h w)', head_num=int(self.head_num), head_dim=int(self.head_dim)) v = rearrange(v, 'b (head_num head_dim) h w -> b head_num head_dim (h w)', head_num=int(self.head_num), head_dim=int(self.head_dim)) # (B, head_num, head_dim, head_dim) attn = q @ k.transpose(-2, -1) * self.scaler attn = self.attn_drop(attn.softmax(dim=-1)) # (B, head_num, head_dim, N) attn = attn @ v # (B, C, H_, W_) attn = rearrange(attn, 'b head_num head_dim (h w) -> b (head_num head_dim) h w', h=int(h_), w=int(w_)) # (B, C, 1, 1) attn = attn.mean((2, 3), keepdim=True) attn = self.ca_gate(attn) return attn * x if __name__ == '__main__': block = SCSA( dim=256, head_num=8, ) input_tensor = torch.rand(1, 256, 32, 32) # 调用模块进行前向传播 output_tensor = block(input_tensor) # 打印输入和输出张量的大小 print("Input size:", input_tensor.size()) print("Output size:", output_tensor.size())