人工神经网络是深度学习的基础，并在图像识别上应用非常多。本代码内容是一个经典的BP网络，S1和S2分别表示中间层和输出层的神经元个数，学习3幅不同类型的图像并输出。-Artificial neural networks are the basis of deep learning and are used in image recognition. The contents of this code is a classic BP network, S1 and S2, respectively