from PIL import Image

def filter(image):
    image_l = image.load()
    new_image = Image.new('L', image.size)
    new_image_l = new_image.load()
    for x in range(2, image.size[0] - 2):
        for y in range(2, image.size[1] - 2):
            pix = sum([sum([image_l[a, b] for b in range(y - 2, y + 3)]) for a in range(x - 2, x + 3)]) - (25 * image_l[x, y])
            if pix > 255:
                pix = 255
            if pix < 0:
                pix = 0 
            new_image_l[x, y] = pix
    return new_image