PIL Best Way To Replace Color?

Question

I am trying to remove a certain color from my image however it\'s not working as well as I\'d hoped. I tried to do the same thing as seen here Using PIL to make all white pi

Answer 1

Using numpy and PIL:

This loads the image into a numpy array of shape (W,H,3), where W is the width and H is the height. The third axis of the array represents the 3 color channels, R,G,B.

import Image
import numpy as np

orig_color = (255,255,255)
replacement_color = (0,0,0)
img = Image.open(filename).convert('RGB')
data = np.array(img)
data[(data == orig_color).all(axis = -1)] = replacement_color
img2 = Image.fromarray(data, mode='RGB')
img2.show()

---

Since orig_color is a tuple of length 3, and data has shape (W,H,3), NumPy broadcasts orig_color to an array of shape (W,H,3) to perform the comparison data == orig_color. The result in a boolean array of shape (W,H,3).

(data == orig_color).all(axis = -1) is a boolean array of shape (W,H) which is True wherever the RGB color in data is original_color.