class Channel_Att(nn.Module): def __init__(self, channels, t=16): super(Channel_Att, self).__init__() self.channels = channels self.bn2 = nn.BatchNorm2d(self.channels, affine=True) def forward(self, x): residual = x x = self.bn2(x) weight_bn = self.bn2.weight.data.abs() / torch.sum(self.bn2.weight.data.abs()) x = x.permute(0, 2, 3, 1).contiguous() x = torch.mul(weight_bn, x) x = x.permute(0, 3, 1, 2).contiguous() x = torch.sigmoid(x) * residual # return x
时间: 2023-12-16 17:04:25 浏览: 27
这段代码是一个 PyTorch 模型的定义,它实现了通道注意力机制(Channel Attention)。该模块的输入是一个四维张量 x,其形状为 [batch_size, channels, height, width],其中 channels 是输入特征图的通道数。在该模块中,首先对输入 x 进行了一个批归一化(Batch Normalization)操作,然后计算每个通道的权重,即 weight_bn,通过将权重与输入张量 x 点乘来加强或减弱每个通道的表示能力,最后再将得到的结果与原始输入张量相加并经过 sigmoid 激活函数得到输出。
该模块使用了一个 t 参数,其默认值为 16。该参数的作用是在计算权重时引入一个缩放因子,以控制注意力机制的强度。
相关问题
class ACmix(nn.Module): def __init__(self, in_planes, out_planes, kernel_att=7, head=4, kernel_conv=3, stride=1, dilation=1): super(ACmix, self).__init__() self.in_planes = in_planes self.out_planes = out_planes self.head = head self.kernel_att = kernel_att self.kernel_conv = kernel_conv self.stride = stride self.dilation = dilation self.rate1 = torch.nn.Parameter(torch.Tensor(1)) self.rate2 = torch.nn.Parameter(torch.Tensor(1)) self.head_dim = self.out_planes // self.head self.conv1 = nn.Conv2d(in_planes, out_planes, kernel_size=1) self.conv2 = nn.Conv2d(in_planes, out_planes, kernel_size=1) self.conv3 = nn.Conv2d(in_planes, out_planes, kernel_size=1) self.conv_p = nn.Conv2d(2, self.head_dim, kernel_size=1) self.padding_att = (self.dilation * (self.kernel_att - 1) + 1) // 2 self.pad_att = torch.nn.ReflectionPad2d(self.padding_att) self.unfold = nn.Unfold(kernel_size=self.kernel_att, padding=0, stride=self.stride) self.softmax = torch.nn.Softmax(dim=1) self.fc = nn.Conv2d(3 * self.head, self.kernel_conv * self.kernel_conv, kernel_size=1, bias=False) self.dep_conv = nn.Conv2d(self.kernel_conv * self.kernel_conv * self.head_dim, out_planes, kernel_size=self.kernel_conv, bias=True, groups=self.head_dim, padding=1, stride=stride) self.reset_parameters()逐行解释代码
这段代码是定义了一个名为ACmix的类,继承自PyTorch中的nn.Module。它包含了一些卷积、全连接、非线性激活函数等层,用于实现图像处理任务中的注意力机制和特征融合。
具体来说,逐行解释代码如下:
```
class ACmix(nn.Module):
def __init__(self, in_planes, out_planes, kernel_att=7, head=4, kernel_conv=3, stride=1, dilation=1):
super(ACmix, self).__init__()
```
定义ACmix类,其中包含了初始化函数__init__()。其中in_planes表示输入特征图的通道数,out_planes表示输出特征图的通道数,kernel_att表示注意力机制的卷积核大小,head表示注意力机制的头数,kernel_conv表示特征融合的卷积核大小,stride表示卷积的步长,dilation表示卷积的膨胀率。
```
self.in_planes = in_planes
self.out_planes = out_planes
self.head = head
self.kernel_att = kernel_att
self.kernel_conv = kernel_conv
self.stride = stride
self.dilation = dilation
self.rate1 = torch.nn.Parameter(torch.Tensor(1))
self.rate2 = torch.nn.Parameter(torch.Tensor(1))
self.head_dim = self.out_planes // self.head
```
将输入的参数保存到类的成员变量中,其中rate1和rate2是需要学习的参数,用于调整注意力机制中的权重。
```
self.conv1 = nn.Conv2d(in_planes, out_planes, kernel_size=1)
self.conv2 = nn.Conv2d(in_planes, out_planes, kernel_size=1)
self.conv3 = nn.Conv2d(in_planes, out_planes, kernel_size=1)
```
定义三个卷积层,其中conv1和conv2用于计算注意力机制,conv3用于特征融合。
```
self.conv_p = nn.Conv2d(2, self.head_dim, kernel_size=1)
```
定义一个卷积层,用于将注意力机制中的特征图转换为头数的通道数。
```
self.padding_att = (self.dilation * (self.kernel_att - 1) + 1) // 2
self.pad_att = torch.nn.ReflectionPad2d(self.padding_att)
self.unfold = nn.Unfold(kernel_size=self.kernel_att, padding=0, stride=self.stride)
self.softmax = torch.nn.Softmax(dim=1)
```
定义一些辅助层,其中padding_att表示注意力机制的填充大小,pad_att表示进行反射填充的层,unfold表示对特征图进行展开的层,softmax表示对展开后的特征图进行softmax操作的层。
```
self.fc = nn.Conv2d(3 * self.head, self.kernel_conv * self.kernel_conv, kernel_size=1, bias=False)
self.dep_conv = nn.Conv2d(self.kernel_conv * self.kernel_conv * self.head_dim, out_planes,
kernel_size=self.kernel_conv, bias=True, groups=self.head_dim, padding=1,
stride=stride)
```
定义特征融合的卷积层和深度可分离卷积层,其中fc层用于将展开后的特征图进行特征融合,dep_conv层用于将融合后的特征图进行输出。
```
self.reset_parameters()
```
初始化模型参数。
class SelfAttention(nn.Module): def __init__(self,in_c,out_c,fm_sz,pos_bias = False): super(SelfAttention,self).__init__() self.w_q = nn.Conv2d(in_channels = in_c,out_channels = out_c,kernel_size = 1) self.w_k = nn.Conv2d(in_channels = in_c,out_channels = out_c,kernel_size = 1) self.w_v = nn.Conv2d(in_channels = in_c,out_channels = out_c,kernel_size = 1) self.pos_code = self.__getPosCode(fm_sz,out_c) self.softmax = nn.Softmax(dim = 2) self.pos_bias = pos_bias 改写为twensorflow形式
可以将这段PyTorch代码改写为如下的TensorFlow代码:
```python
import tensorflow as tf
from tensorflow import keras
class SelfAttention(keras.layers.Layer):
def __init__(self, in_c, out_c, fm_sz, pos_bias=False):
super(SelfAttention, self).__init__()
self.w_q = keras.layers.Conv2D(filters=out_c, kernel_size=1, input_shape=(None, None, in_c))
self.w_k = keras.layers.Conv2D(filters=out_c, kernel_size=1, input_shape=(None, None, in_c))
self.w_v = keras.layers.Conv2D(filters=out_c, kernel_size=1, input_shape=(None, None, in_c))
self.pos_code = self.__getPosCode(fm_sz, out_c)
self.softmax = keras.layers.Softmax(axis=2)
self.pos_bias = pos_bias
def __getPosCode(self, fm_sz, out_c):
x = []
for i in range(fm_sz):
x.append([np.sin, np.cos][i % 2](1 / (10000 ** (i // 2 / fm_sz))))
x = tf.convert_to_tensor([x], dtype=tf.float32)
return tf.concat([(x + tf.transpose(x)).unsqueeze(0) for i in range(out_c)], axis=0)
def call(self, x):
q, k, v = self.w_q(x), self.w_k(x), self.w_v(x)
pos_code = tf.concat([self.pos_code.unsqueeze(0) for i in range(x.shape[0])], axis=0)
if self.pos_bias:
att_map = tf.matmul(q, tf.transpose(k, perm=[0, 1, 3, 2])) + pos_code
else:
att_map = tf.matmul(q, tf.transpose(k, perm=[0, 1, 3, 2])) + tf.matmul(q, tf.transpose(pos_code, perm=[0, 1, 3, 2]))
am_shape = att_map.shape
att_map = self.softmax(tf.reshape(att_map, [am_shape[0], am_shape[1], am_shape[2] * am_shape[3]]))
att_map = tf.reshape(att_map, am_shape)
return att_map * v
```
需要注意的是,这里的代码只是一种可能的TensorFlow实现方式,具体还需要根据实际情况进行微调。