private void pixelate(BufferedImage im, int x, int y, int w, int h, int block) {
      int width = im.getWidth();
      int height = im.getHeight();
      int hw = w >> 1;
      int hh = h >> 1;
      int[] pixels = im.getRGB(0, 0, width, height, null, 0, width);
      int[] temp = pixels.clone();
      
      for(int yy = -hh; yy < hh; yy++) {
         for(int xx = -hw; xx < hw; xx++) {
            int col = 0;
            for(int i = 0; i < block; i++) {
               int yd = yy / block + y + i;
               if(yd < 0 || yd >= height) continue;
               for(int j = 0; j < block; j++) {
                  int xd = xx / block + x + j;
                  if(xd < 0 || xd >= width) continue;
                  col += pixels[yd * width + xd];
               }
            }
            if(yy + y < 0 || yy + y >= height || xx + x < 0 || xx + x >= width) continue;
            temp[(yy + y) * width + (xx + x)] = col / (block * block);
         }
      }
      
      im.setRGB(0, 0, width, height, temp, 0, width);
   }