Crop a PNG image to its minimum size

Question

How to cut off the blank border area of a PNG image and shrink it to its minimum size using Python?

Answer 1

I think it's necessary to supplement @Frank Krueger's answer. He makes a good point, but it doesn't include how to properly crop extra border color out of an image. I found that here. Specifically, I found this useful:

from PIL import Image, ImageChops

def trim(im):
    bg = Image.new(im.mode, im.size, im.getpixel((0,0)))
    diff = ImageChops.difference(im, bg)
    diff = ImageChops.add(diff, diff, 2.0, -100)
    bbox = diff.getbbox()
    if bbox:
        return im.crop(bbox)

im = Image.open("bord3.jpg")
im = trim(im)
im.show()