Trim image whitespace

trim.py

import numpy as np
from PIL import Image, ImageChops
import sys
import numpy as np

def trim(im):
    bg = Image.new(im.mode, im.size, im.getpixel((0,0)))
    size = im.size
    
    top_left_pixel = im.getpixel((0,0))
    bottom_right_pixel = im.getpixel((size[0] - 1, size[1] - 1))
    
    is_top_left_white = top_left_pixel[0] >= 240 and top_left_pixel[1] >= 240 and top_left_pixel[2]
    is_bottom_right_white = bottom_right_pixel[0] >= 240 and bottom_right_pixel[1] >= 240 and bottom_right_pixel[2] >= 240
    
    is_top_left_transparent = top_left_pixel[3] < 20 if len(top_left_pixel) > 3 else False
    is_bottom_right_transparent = bottom_right_pixel[3] < 20 if len(bottom_right_pixel) > 3 else False
    
    if (is_top_left_white and is_bottom_right_white) or (is_top_left_transparent and is_bottom_right_transparent):
        diff = ImageChops.difference(im, bg)
        offset = round(size[1] / 100 * 4);
        diff = ImageChops.add(diff, diff, 2.0, -100)
        bbox = diff.getbbox()
        if bbox:
            return im.crop((max(bbox[0] - offset, 0), max(bbox[1] - offset, 0), min(bbox[2] + offset, size[0]), min(bbox[3] + offset, size[1])))
        else:
            return im
    else:
        print('No change because no transparency or no white background')
        return im

im = Image.open(sys.argv[1])
im = trim(im)
im.save(sys.argv[2])

Usage:

python trim.py input.jpg output.jpg