MNIST数据集提取数据

import numpy as np
import struct
import cv2

def readfile():
    #
    with open('../dataset/t10k-images.idx3-ubyte','rb') as f1:
        buf1 = f1.read()
    return buf1
def get_image(buf1):
    image_index = 0
    image_index +=struct.calcsize('>IIII')
    magic,numImages,imgRows,imgCols = struct.unpack_from(">IIII",buf1,0)
    im = []
    for i in range(numImages):
        temp = struct.unpack_from('>784B',buf1,image_index)
        im=np.array(temp)
        im2=im.reshape(28,28)
        cv2.imwrite(str(i)+".jpg",im2)
        image_index += struct.calcsize('>784B')
        if i % 20 ==0:
            print i
        else:
            print i,
if __name__ == "__main__":
    image_data = readfile()
    get_image(image_data)
    cv2.waitKey(0)
    cv2.destroyAllWindows()