Replacing normal convolutions with group convolutions can significantly increase the computational efficiency of modern deep convolution networks, which has been widely adopted in compact network architecture designs. However, existing group convolutions undermine the original network structures by cutting off some connections permanently resulting in significant accuracy degradation. In this paper, we propose dynamic group convolution (DGC) that adaptively selects which part of input channels to be connected within each group for individual samples on the fly. Specifically, we equip each group with a small feature selector to automatically select the most important input channels conditioned on the input images. Multiple groups can adaptively capture abundant and complementary visual/semantic features for each input image. The DGC preserves the original network structure and has similar computational efficiency as the conventional group convolutions simultaneously. Extensive experiments on multiple image classification benchmarks including CIFAR-10, CIFAR-100 and ImageNet demonstrate its superiority over the existing group convolution techniques and dynamic execution methods. The code is available at https://github.com/zhuogege1943/dgc.

本文提出一种动态组卷积 (Dynamic Group Convolution, DGC) 方法，它不仅保留了原有网络结构，还能够根据输入图像动态选择连接哪些输入通道，以实现对图像语义特征的自适应提取，有效提高了卷积神经网络的计算效率和图像分类性能。

动态组卷积用于加速卷积神经网络