search for item in 《The Binding of Isaac 》

search.py

import os
from PIL import Image
import glob

# icons downloaded from http://bindingofisaacrebirth.gamepedia.com/
IMGS_PATH = "./img/*"

# clipboard to image file
if os.system('pngpaste isaac_clip.png'):
    exit()
clip = Image.open('isaac_clip.png')
clip = clip.convert('RGB')
clip.thumbnail([i / 2 for i in clip.size])
pxl_clip = clip.load()

min_err = float('inf')
the_item = None

bad_list = ('20 20 Icon', 'The Bean Icon.png',
            'The Black Bean Icon.png', 'Wire Coat Hanger Icon.png',
            'A Lump Of Coal Icon.png')

for name in glob.glob(IMGS_PATH):
    # skip
    if any(name.endswith(bad) for bad in bad_list):
        continue

    item = Image.open(name).convert('RGBA')

    # search
    pxl_item = item.load()
    min_diff = float('inf')
    min_diff_pos = None
    for si in xrange(clip.size[0]):
        if si + item.size[0] >= clip.size[0]:
            break
        for sj in xrange(clip.size[1]):
            if sj + item.size[1] >= clip.size[1]:
                break
            diff = 0
            for i in xrange(item.size[0]):
                for j in xrange(item.size[1]):
                    if pxl_item[i, j][3]:
                        diff += sum(abs(ca - cb) for (ca, cb)
                                    in zip(pxl_clip[si + i, sj + j], pxl_item[i, j]))
            if diff < min_diff:
                min_diff = diff
                min_diff_pos = (si, sj)

    pxl_cnt = 0
    for i in xrange(item.size[0]):
        for j in xrange(item.size[1]):
            if pxl_item[i, j][3]:
                pxl_cnt += 1

    err = 1.0 * min_diff / pxl_cnt
    if err < min_err:
        min_err = err
        the_item = name

print min_err, the_item