I. Introduction
Image classification is an image processing method that distinguishes image information according to its different features. Neural networks are often used for image classification. Artificial Neural Network (ANN) is a mathematical model that simulates the processing of complex information by human brain [1]. It can be applied to many fields, such as financial economics [2], healthcare [3], power systems [4], satellite [5], fault detection [6], voice recognition [7], pattern recognition [8], etc. However, at present, many ANN structures, such as Multi-Layer Perceptron (MLP) networks [9] and Hopfield network [10], will produce a relatively serious catastrophic forgetting problem [11] with the continuous entry of new pattern, resulting in the loss of original information. The problem of catastrophic forgetting is also known as the stability plasticity dilemma, which means that after learning new knowledge, the previously learned knowledge is almost completely forgotten. Convolutional Neural Network (CNN) is one of the commonly used image classification methods. Offline learning is based on CNN scratch training to learn new knowledge. Whenever we need to learn new data, we need to learn the learned data and new data together again, which greatly increases the training time. In order to solve this problem, we need online learning to reduce training time.