import numpy as np
import matplotlib.pyplot as plt


def read_mnist_images(filename):
    with open(filename, 'rb') as f:
        # 读取魔术数字、图像数量、行数、列数
        magic_number = int.from_bytes(f.read(4), 'big')
        number_of_images = int.from_bytes(f.read(4), 'big')
        rows = int.from_bytes(f.read(4), 'big')
        cols = int.from_bytes(f.read(4), 'big')

        # 读取图像数据
        images = np.frombuffer(f.read(), dtype=np.uint8)
        images = images.reshape((number_of_images, rows, cols))
    return images


# 修改为您的路径
filename = './data/MNIST/raw/train-images-idx3-ubyte'

images = read_mnist_images(filename)

# 显示第一张图像
plt.imshow(images[0], cmap='gray')
plt.title("First Image in MNIST Dataset")
plt.show()

把最后第三行的0，修改成别的数字，就会显示某张数字。 

运行之后，结果如下