ndvi.py

import numpy as np
from PIL import Image

section_size = 20

im = Image.open("ndvi_test.jpg")
px = np.asarray(im)

x = 0
y = 0

imgheight, imgwidth, _ = px.shape
for i in range(0, imgheight - 1, section_size):
    for j in range(0, imgwidth - 1, section_size):
        section = px[i:i+section_size, j:j+section_size]
        avg_color = np.average(section, axis=(0, 1))
        for section_i in range(i, i+section_size):
            for section_j in range(j, j+section_size):
                px[min(section_i, imgheight - 1), min(
                    section_j, imgwidth - 1)] = avg_color

out = Image.fromarray(np.uint8(px))
out.show()
# im.show()
# im.save("ndvi_test_out.jpg")