RGB to grayscale¶
This example converts an image with RGB channels into an image with a single grayscale channel.
The value of each grayscale pixel is calculated as the weighted sum of the corresponding red, green and blue pixels as:
Y = 0.2125 R + 0.7154 G + 0.0721 B
These weights are used by CRT phosphors as they better represent human perception of red, green and blue than equal weights. 1
import numpy as np import matplotlib.pyplot as plt from skimage import data from skimage.color import rgb2gray original = data.astronaut() grayscale = rgb2gray(original) fig, axes = plt.subplots(1, 2, figsize=(8, 4)) ax = axes.ravel() ax.imshow(original) ax.set_title("Original") ax.imshow(grayscale, cmap=plt.cm.gray) ax.set_title("Grayscale") fig.tight_layout() plt.show()
Total running time of the script: ( 0 minutes 0.275 seconds)