matplotlib>pyplot map colors wont work

edit

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import cv2
from matplotlib import pyplot as plt
import numpy as np


img1= cv2.imread('hristos_karaiskos.jpg')
#img1= img[:,:,::-1]


replicate= cv2.copyMakeBorder(img1,10,10,10,10,cv2.BORDER_REPLICATE)

plt.subplot(231)
plt.imshow(img1, 'Pastel1')
plt.subplot(232)
plt.imshow(replicate,'gray')
plt.show()

My image wont change color, not or the "pastel1" not to the 'gray"