OpenCV: img[:], img[:, :], img[:, 0], img[:, 1], img[:, 2], img[:, :, 0], img[:, :, 1], img[:, :, 2] equivalent understanding

一、print(img)、print(img[:])、print(img[:, :])

print（img)print(img[:])print(img[:, :])

same result, print image array

Two, img[:, 0] and img[:, :, 0], img[:, 1] and img[:, :, 1], img[:, 2] and img[:, :, 2]

img[:, 0]img[:, :, 0]

img[:, 1]img[:, :, 1]

img[:, 2]img[:, :, 2]

img[:, 0] / img[:, 1] / img[:, 2]: Three-channel pixels representing image columns.

img[:, :, 0] / img[:, :, 1] / img[:, :, 2]: Pixels representing a single channel of the image.