内容概要

1.数据集的介绍

MNIST(THE MNIST DATABASE of handwritten digits)
  主要是由手写数字的像素点数据组成的，每一个像素点的取值为[0,255]之间。以一个例子来具体说明：

example.png

![image.png](http://upload-images.jianshu.io/upload_images/4154180-4a777188334aef3a.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

![image.png](http://upload-images.jianshu.io/upload_images/4154180-cca7b2d00d31bbb8.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)

![image.png](http://upload-images.jianshu.io/upload_images/4154180-fdece51b9e8cbbe5.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)