Between-class Learning for Image Classification

TL;DR

This paper introduces Between-Class learning (BC learning), a novel image classification method that mixes images from different classes to improve model generalization, inspired by sound mixing techniques.

Contribution

The paper presents a new image mixing approach based on sound mixing principles, significantly enhancing classification accuracy on benchmark datasets.

Findings

Achieved 19.4% top-1 error on ImageNet-1K

Achieved 2.26% top-1 error on CIFAR-10

Proved effectiveness of waveform-based image mixing

Abstract

In this paper, we propose a novel learning method for image classification called Between-Class learning (BC learning). We generate between-class images by mixing two images belonging to different classes with a random ratio. We then input the mixed image to the model and train the model to output the mixing ratio. BC learning has the ability to impose constraints on the shape of the feature distributions, and thus the generalization ability is improved. BC learning is originally a method developed for sounds, which can be digitally mixed. Mixing two image data does not appear to make sense; however, we argue that because convolutional neural networks have an aspect of treating input data as waveforms, what works on sounds must also work on images. First, we propose a simple mixing method using internal divisions, which surprisingly proves to significantly improve performance. Second, we propose a mixing method that treats the images as waveforms, which leads to a further improvement in performance. As a result, we achieved 19.4% and 2.26% top-1 errors on ImageNet-1K and CIFAR-10, respectively.