import cv2
import numpy as np
from matplotlib import pyplot as plt
BLUE = [255, 0, 0]
img1 = cv2.imread('pic1.png', 1)
# change the value of bgr
b, g, r = cv2.split(img1)
img2 = cv2.merge([r, g, b])
img3 = cv2.merge([r, g, b])
img4 = cv2.merge([r, g, b])
img5 = cv2.merge([r, g, b])
# make one of bgr become 0
img3[:, :, 0] = 0
img4[:, :, 1] = 0
img5[:, :, 2] = 0
# make all kind of border
replicate = cv2.copyMakeBorder(img1, 10, 10, 10, 10, cv2.BORDER_REPLICATE)
reflect = cv2.copyMakeBorder(img1, 10, 10, 10, 10, cv2.BORDER_REFLECT)
reflect101 = cv2.copyMakeBorder(img1, 10, 10, 10, 10, cv2.BORDER_REFLECT_101)
wrap = cv2.copyMakeBorder(img1, 10, 10, 10, 10, cv2.BORDER_WRAP)
constant = cv2.copyMakeBorder(img1, 10, 10, 10, 10, cv2.BORDER_CONSTANT, value=BLUE)
# plot figure
plt.subplot(331), plt.imshow(img2), plt.title('origin')
plt.subplot(332), plt.imshow(replicate, 'gray'), plt.title('replicate')
plt.subplot(333), plt.imshow(reflect, 'gray'), plt.title('reflect')
plt.subplot(334), plt.imshow(reflect101, 'gray'), plt.title('reflect101')
plt.subplot(335), plt.imshow(wrap, 'gray'), plt.title('wrap')
plt.subplot(336), plt.imshow(constant, 'gray'), plt.title('constant')
plt.subplot(337), plt.imshow(img3), plt.title('img3')
plt.subplot(338), plt.imshow(img4), plt.title('img4')
plt.subplot(339), plt.imshow(img5), plt.title('img5')
plt.show()