img0 = img[:, :, 0]
img1 = img[:, :, 1]
img2 = img[:, :, 2]

img20 = np.array([[0 if (c % 32) < 16 else d for c, d in zip(range(len(img0)), a)] for a in img0], np.uint8)
img21 = np.array([[0 if (c % 32) < 16 else d for c, d in zip(range(len(img1)), a)] for a in img1], np.uint8)
img22 = np.array([[0 if (c % 32) < 16 else d for c, d in zip(range(len(img2)), a)] for a in img2], np.uint8)

imgf = np.zeros_like(img)
imgf[:, :, 0] = img20
imgf[:, :, 1] = img21
imgf[:, :, 2] = img22

functions.show(imgf)