数字水印|Arnold变换的Python代码实现（灰度图版）

    import cv2
    import numpy as np
    from matplotlib import pyplot as plt
    
    
    def arnold(img, shuffle_times, a, b):
    r, c, d = img.shape
    img = img[:, :, 0]
    p = np.zeros((r, c), np.uint8)
    for s in range(shuffle_times):
        for i in range(r):
            for j in range(c):
                x = (i + b * j) % r
                y = (a * i + (a * b + 1) * j) % c
                p[x, y] = img[i, j]
        img =