How to implement spatial attention mechanism in Deep Network Designer

How to implement spatial attention mechanism in Deep Network Designer

spatial attention:

input = [256,256,64]

max_pool = max(input,[],3);

men_pool = mean(input,3);

[Chuan Yan]

average-poolingand max-poolingoperations along the channel axis respectively in Deep Network Designeri

Answer 1

[Aditya]

To implement a spatial attention mechanism within a deep learning model using MATLAB's Deep Network Designer, you would typically follow a series of steps to first create the attention module separately, and then integrate it into your network. The spatial attention mechanism you're describing seems to follow a common pattern where both max pooling and mean pooling across the channels are used to highlight important spatial features.

Step 1: Define the Spatial Attention Layer

Since custom operations like spatial attention are not directly available in Deep Network Designer's layer catalog, you would typically define this as a custom layer in MATLAB code. However, for simplicity and to provide a conceptual understanding, I'll describe the process focusing on the operations involved.

For custom implementation, you would define a class inheriting from nnet.layer.Layer and implement the spatial attention mechanism inside its forward function.

Step 2: Implementing Pooling Operations

Max and mean pooling across the channels can be done using operations like:

% Assuming 'input' is the input tensor of size [256, 256, 64]
max_pool = max(input, [], 3);  % Max pooling across channels
mean_pool = mean(input, 3);    % Mean pooling across channels

Step 3: Combining Features and Applying Convolution

After pooling, you would concatenate these maps and apply a convolution. In code, this step might require a custom layer or function to handle the concatenation and convolution:

% Concatenating along the third dimension
combined_features = cat(3, max_pool, mean_pool);

% Applying a convolution to get a single channel output
% Note: You need to define 'convLayer' based on your network architecture
attention_map = convolution2dLayer([7, 7], 1, 'Padding', 'same').forward(combined_features);

Step 4: Applying the Attention Map

Finally, you apply the spatial attention map to the original input:

% Assuming 'attention_map' is resized or processed to match input dimensions if needed
modulated_input = input .* repmat(attention_map, [1, 1, 64]);

[shen hedong]

May I ask how to use MATLAB code to build an ECA module? The ECA module can refer to this paper: ECA Net: Efficient Channel Attention for Deep Convolutional Neural Networks.

Paper address: https://arxiv.org/abs/1910.03151

I found the following Python code about ECA: but I don't know how to implement "squeeze" and "transpose" in MATLAB.Please help me!

class ECA(nn.Module):
    """Constructs a ECA module.
    Args:
        channel: Number of channels of the input feature map
        k_size: Adaptive selection of kernel size
    """
    def __init__(self, c1,c2, k_size=3):
        super(ECA, self).__init__()
        self.avg_pool = nn.AdaptiveAvgPool2d(1)
        self.conv = nn.Conv1d(1, 1, kernel_size=k_size, padding=(k_size - 1) // 2, bias=False)
        self.sigmoid = nn.Sigmoid()
    def forward(self, x):
        # feature descriptor on the global spatial information
        y = self.avg_pool(x)
        y = self.conv(y.squeeze(-1).transpose(-1, -2)).transpose(-1, -2).unsqueeze(-1)
        # Multi-scale information fusion
        y = self.sigmoid(y)
        return x * y.expand_as(x)