from skimage import data
from skimage.color import rgb2gray
import matplotlib.pyplot as plt

plt.figure(figsize=(15,15))

coffee=data.coffee()

plt.subplot(1,2,1)
plt.imshow(coffee)

gray_coffee=rgb2gray(coffee)

plt.subplot(1,2,2)
plt.imshow(gray_coffee,cmap="gray")

plt.show()