image_ops.py

import numpy as np
from PIL import Image

image = Image.open("../manning-logo.png").convert("L")
width, height = image.size
image_arr = np.array(image)

brighter_arr = image_arr + 5
Image.fromarray(brighter_arr).save("brighter.png")
brighter2_arr = image_arr * 2
Image.fromarray(brighter2_arr).save("brighter2.png")

print(image_arr.max(), image_arr.dtype)
print(brighter_arr.max(), brighter_arr.dtype)
print(brighter2_arr.max(), brighter2_arr.dtype)


brighter3_arr = image_arr.astype(np.uint16)
brighter3_arr = brighter3_arr * 2
print(brighter3_arr.max(), brighter3_arr.dtype)
brighter3_arr = np.minimum(brighter3_arr, 255)  # do not confuse with min
print(brighter3_arr.max(), brighter3_arr.dtype)
brighter3_arr = brighter3_arr.astype(np.uint8)
print(brighter3_arr.max(), brighter3_arr.dtype)
Image.fromarray(brighter3_arr).save("brighter3.png")