Crop white borders from images - numpy, pillow

autocrop.py

import numpy
from PIL import Image
from matplotlib.colors import rgb_to_hsv

minions = Image.open('minons_test_autocrop_lossy.jpg')

def autocrop(image,thresh_v=255,thresh_s=.01,pad=0):

    a = numpy.asarray(image)
    hsv = rgb_to_hsv(a.take([0,1,2],axis=2))

    white = (hsv.take(1,axis=2) <= thresh_s) * (hsv.take(2,axis=2) >= thresh_v)

    nonempty_cols = numpy.where(white.min(axis=0) == False)[0]
    nonempty_rows = numpy.where(white.min(axis=1) == False)[0]
    bbox = (min(nonempty_rows)-pad, max(nonempty_rows)+pad, min(nonempty_cols)-pad, max(nonempty_cols)+pad)
    cropped = a[bbox[0]:bbox[1] + 2, bbox[2]:bbox[3] + 0, :]

    return Image.fromarray(cropped)

out = autocrop(minions,thresh_v=240)

from matplotlib import pyplot as plt
plt.imshow(out)
plt.show()