ECA-Net: Efficient Channel Attention for Deep Convolutional Neural Networks (1910.03151v4)

Abstract: Recently, channel attention mechanism has demonstrated to offer great potential in improving the performance of deep convolutional neural networks (CNNs). However, most existing methods dedicate to developing more sophisticated attention modules for achieving better performance, which inevitably increase model complexity. To overcome the paradox of performance and complexity trade-off, this paper proposes an Efficient Channel Attention (ECA) module, which only involves a handful of parameters while bringing clear performance gain. By dissecting the channel attention module in SENet, we empirically show avoiding dimensionality reduction is important for learning channel attention, and appropriate cross-channel interaction can preserve performance while significantly decreasing model complexity. Therefore, we propose a local cross-channel interaction strategy without dimensionality reduction, which can be efficiently implemented via $1D$ convolution. Furthermore, we develop a method to adaptively select kernel size of $1D$ convolution, determining coverage of local cross-channel interaction. The proposed ECA module is efficient yet effective, e.g., the parameters and computations of our modules against backbone of ResNet50 are 80 vs. 24.37M and 4.7e-4 GFLOPs vs. 3.86 GFLOPs, respectively, and the performance boost is more than 2% in terms of Top-1 accuracy. We extensively evaluate our ECA module on image classification, object detection and instance segmentation with backbones of ResNets and MobileNetV2. The experimental results show our module is more efficient while performing favorably against its counterparts.

• The paper introduces the ECA module, a novel design that avoids dimensionality reduction to preserve full channel information.
• It employs a 1D convolution to efficiently capture local cross-channel interactions and adaptively adjust kernel size based on channel dimensions.
• Experimental results across CNN architectures demonstrate that ECA-Net boosts accuracy with minimal computational and parameter overhead.

ECA-Net: Efficient Channel Attention for Deep Convolutional Neural Networks

The paper "ECA-Net: Efficient Channel Attention for Deep Convolutional Neural Networks" addresses a critical aspect of convolutional neural network (CNN) design: enhancing performance through the integration of attention mechanisms while maintaining low model complexity. Traditional channel attention mechanisms, exemplified by the Squeeze-and-Excitation Networks (SENet), have demonstrated significant performance gains but often at the cost of increased model complexity. This paper introduces the Efficient Channel Attention (ECA) module, which strives to balance the trade-offs between performance and complexity effectively.

Key Contributions and Methodology

The paper is structured around dissecting the conventional SENet module and proposing a streamlined yet effective alternative—the ECA module. The primary contributions are:

1. Avoiding Dimensionality Reduction: SENet involves dimensionality reduction to control model complexity, which, while reducing parameters, disrupts the direct correspondence between channels and their learned attention weights. ECA-Net circumvents this by avoiding dimensionality reduction and instead uses $1D$ convolution that maintains full channel dimensionality, preserving critical information.
2. Local Cross-Channel Interaction: The ECA module captures local cross-channel interactions efficiently through a $1D$ convolutional layer. This method leverages adjacent channel information, improving the channel attention mechanism without significant computational overhead.
3. Adaptive Kernel Size: The paper introduces a method to adaptively select the kernel size for the $1D$ convolution based on the channel dimensionality. This adaptive mechanism ensures that the network dynamically adjusts its attention coverage, optimizing performance further.

Experimental Results

The experimental evaluation demonstrates that ECA-Net achieves substantial performance improvements over baseline models and existing attention mechanisms across several tasks, using various CNN architectures like ResNet-50, ResNet-101, ResNet-152, and MobileNetV2.

Image Classification

The paper provides extensive results on ImageNet classification:

• ResNet-50: ECA-Net achieves a Top-1 accuracy improvement of 2.28% over the baseline ResNet-50, with no significant increase in parameters or computational cost.
• ResNet-101 and ResNet-152: Similar trends are observed, with ECA-Net yielding performance gains with marginal increase in complexity.
• MobileNetV2: ECA-Net enhances the performance of lightweight architectures, achieving superior results to SENet with fewer parameters and faster training and inference times.

Object Detection and Instance Segmentation

The efficacy of ECA-Net extends beyond image classification to tasks such as object detection and instance segmentation, evaluated on the COCO dataset using frameworks like Faster R-CNN, Mask R-CNN, and RetinaNet. Key findings include:

• Faster R-CNN: With ResNet-50 and ResNet-101 backbones, ECA-Net outperforms SENet in terms of Average Precision (AP) while maintaining similar model complexities.
• Mask R-CNN and RetinaNet: ECA-Net consistently results in better detection and segmentation performance, demonstrating its generalizability and robustness across different applications.

Implications and Future Directions

The introduction of ECA-Net presents several theoretical and practical implications:

• Theoretical: The avoidance of dimensionality reduction and efficient local cross-channel interaction suggests a paradigm shift towards more straightforward yet effective attention mechanisms. It highlights the potential redundancy of overly complex networks in achieving state-of-the-art performance.
• Practical: ECA-Net’s low computational cost and parameter efficiency are particularly advantageous for deployment on resource-constrained devices, expanding the applicability of advanced CNNs in real-world scenarios.

Looking forward, the development of the ECA module sets the stage for future research in attention mechanisms. Adapting ECA to other CNN architectures, such as ResNeXt and Inception, and exploring combinations with spatial attention modules could lead to further advancements in the field.

Conclusion

The paper "ECA-Net: Efficient Channel Attention for Deep Convolutional Neural Networks" presents a compelling case for revisiting and refining channel attention mechanisms. By emphasizing efficiency and avoiding unnecessary complexity, ECA-Net enhances the performance of various CNN architectures significantly. The findings and methodologies proposed offer fertile ground for future research in optimizing neural network architectures for both performance and resource efficiency.