def dither(old):
    w, h = old.size
    raw = list(old.getdata())
    for y in range(h):
        for x in range(w):
            r, g, b = raw[x + y * w]
            diff = 255*3
            closest_color = (255,255,255)
            selected_object = ''
            for g_obj in palette.keys():
                rc, gc, bc = palette[g_obj]
                cdiff = abs(r - rc) + abs(g - gc) + abs(b - bc)
                if cdiff <= diff:
                    diff = cdiff
                    closest_color = (rc, gc, bc)
            rn, gn, bn = closest_color
            rq = r - rn
            gq = g - gn
            bq = b - bn
            raw[x + y * w] = (rn, gn, bn)
            for diffusion in matrix:
                offset_x, offset_y, err_diff = diffusion
                offset_x = x + offset_x
                offset_y = y + offset_y
                if offset_x + offset_y * w >= w*h or offset_x + offset_y * w < 0:
                    continue
                offset_r, offset_g, offset_b = raw[offset_x + offset_y * w]
                offset_r += int(rq * err_diff)
                offset_g += int(gq * err_diff)
                offset_b += int(bq * err_diff)
                raw[offset_x + offset_y * w] = (limit_byte(offset_r), limit_byte(offset_g), limit_byte(offset_b))
    new_img = Image.new('RGB', (w, h))
    new_img.putdata(raw)
    return new_img