sclass G22ColorWalker > G22Walker<IRGBImage> {

  // the ideal image it is looking for (set/get)

  int[] rememberedImage; // size visionW*visionH

  // only works when we already have a rememberedImage

  double scorePosition(Pt pos, IRGBImage image) {

    int vx = pos.x-visionW, vy = pos.y-visionH, i = 0;

    int diff = 0;

    for y to visionH:

      for x to visionW:

        diff += colorDistance(rememberedImage[i++], image.getIntPixel(vx+x, vy+y));

    ret -diff;

  }

  bool hasRememberedImage() { ret rememberedImage != null; }

  void rememberImage(IRGBImage image) {

    if (rememberedImage == null)

      rememberedImage = new int[visionW*visionH];

    int vx = visionX1(), vy = visionY1(), i = 0;

    for y to visionH:

      for x to visionW:

        rememberedImage[i++] = image.getIntPixel(vx+x, vy+y);

  }

}