import numpy as np
import matplotlib.pyplot as plt

img = plt.imread('photo2.jpg')
R = img[:, :, 0]
G = img[:, :, 1]
B = img[:, :, 2]
fig = plt.figure(figsize=(10, 10))
columns = 4
rows = 4

fig.add_subplot(rows, columns, 1)
plt.title("O")
plt.imshow(img)
fig.add_subplot(rows, columns, 2)
plt.title("R")
plt.imshow(R)
fig.add_subplot(rows, columns, 3)
plt.title("G")
plt.imshow(G)
fig.add_subplot(rows, columns, 4)
plt.title("B")
plt.imshow(B)

fig.add_subplot(rows, columns, 6)
plt.imshow(R, cmap=plt.cm.gray, vmin=0, vmax=255)
fig.add_subplot(rows, columns, 7)
Y = 0.2126 * R + 0.7152 * G + 0.0722 * B
plt.imshow(Y, cmap=plt.cm.gray, vmin=0, vmax=255)

plt.show()