def list_images(path=['.']):
    """ Return list of image files """
    for image_dir in set(path):
        if not os.path.isdir(image_dir):
            continue
        for filename in os.listdir(image_dir):
            bname, ext = os.path.splitext(filename)
            if ext.lower() not in VALID_IMAGE_EXTS:
                continue

            filepath = os.path.join(image_dir, filename)
            yield strutils.decode(filepath)
Return list of image files