for i in range(0, num_images):
    t = time.time()
im = Image.open('%03i.png' % i)
w, h = im.size
imc = im.crop((w - 50, h - 50, w + 50, h + 50))
print('Time to open: %.4f seconds' % (time.time() - t))
data = np.array(imc)
Load just part of an image in python