Remove any unnecessary whitespace from the edges of the source image

autocrop.py

# copy from easy_thumbnails
from PIL import Image, ImageChops

def is_transparent(image):
    """
    Check to see if an image is transparent.
    """
    if not isinstance(image, Image.Image):
        # Can only deal with PIL images, fall back to the assumption that that
        # it's not transparent.
        return False
    return (image.mode in ('RGBA', 'LA') or
            (image.mode == 'P' and 'transparency' in image.info))


def autocrop(im, **kwargs):
    """
    Remove any unnecessary whitespace from the edges of the source image.

    This processor should be listed before :func:`scale_and_crop` so the
    whitespace is removed from the source image before it is resized.

    autocrop
        Activates the autocrop method for this image.

    """
    # If transparent, flatten.
    if is_transparent(im) and False:
        no_alpha = Image.new('L', im.size, (255))
        no_alpha.paste(im, mask=im.split()[-1])
    else:
        no_alpha = im.convert('L')
    # Convert to black and white image.
    bw = no_alpha.convert('L')
    # bw = bw.filter(ImageFilter.MedianFilter)
    # White background.
    bg = Image.new('L', im.size, 255)
    bbox = ImageChops.difference(bw, bg).getbbox()
    if bbox:
        im = im.crop(bbox)
    return im

if __name__ == "__main__":
    import sys
    image_name_list = sys.argv[1:]
    name_dict = dict(map(lambda _: _.split('.'), image_name_list))
    for pre_name in name_dict:
        full_name  = pre_name + '.' + name_dict[pre_name]
        im = Image.open(full_name)
        croped_im = autocrop(im)
        croped_im.save(pre_name + "_croped." + name_dict[pre_name])