resize.py

from PIL import Image


def resize_and_crop(img, size=(255, 255)):
    img = Image.open(img)
    img_ratio = img.size[0] / img.size[1]
    ratio = size[0] / size[1]

    if ratio > img_ratio:
        img = img.resize((size[0], int(size[0] * img.size[1] / img.size[0])),
                         Image.ANTIALIAS)

        box = (0, (img.size[1] - size[1]) / 2, img.size[0],
               (img.size[1] + size[1]) / 2)
        img = img.crop(box)
    elif ratio < img_ratio:
        img = img.resize((int(size[1] * img.size[0] / img.size[1]), size[1]),
                         Image.ANTIALIAS)

        box = ((img.size[0] - size[0]) / 2, 0, (img.size[0] + size[0]) / 2,
               img.size[1])
        img = img.crop(box)
    else:
        # no cropping necessary
        img = img.resize((size[0], size[1]), Image.ANTIALIAS)

    # save thumbnail
    img.save('./thumb.jpg')