Glance and Focus: a Dynamic Approach to Reducing Spatial Redundancy in Image Classification
This addresses efficiency problems for mobile and edge device users by reducing spatial redundancy, though it is incremental as it builds on existing lightweight CNNs.
The paper tackles the high computational cost of using high-resolution images in deep CNNs for image classification by proposing a dynamic framework that processes small, strategically selected inputs via reinforcement learning, achieving a 20% reduction in latency on MobileNet-V3 on an iPhone XS Max without accuracy loss.
The accuracy of deep convolutional neural networks (CNNs) generally improves when fueled with high resolution images. However, this often comes at a high computational cost and high memory footprint. Inspired by the fact that not all regions in an image are task-relevant, we propose a novel framework that performs efficient image classification by processing a sequence of relatively small inputs, which are strategically selected from the original image with reinforcement learning. Such a dynamic decision process naturally facilitates adaptive inference at test time, i.e., it can be terminated once the model is sufficiently confident about its prediction and thus avoids further redundant computation. Notably, our framework is general and flexible as it is compatible with most of the state-of-the-art light-weighted CNNs (such as MobileNets, EfficientNets and RegNets), which can be conveniently deployed as the backbone feature extractor. Experiments on ImageNet show that our method consistently improves the computational efficiency of a wide variety of deep models. For example, it further reduces the average latency of the highly efficient MobileNet-V3 on an iPhone XS Max by 20% without sacrificing accuracy. Code and pre-trained models are available at https://github.com/blackfeather-wang/GFNet-Pytorch.