public static BufferedImage analyzeImage(BufferedImage img){
		
		int w = img.getWidth();
		int h = img.getHeight() / 2;
		
		BufferedImage res = new BufferedImage(w, h, img.getType());
		
		for(int x=0; x<w; x++){
			for(int y=0; y<h; y++){
				
				int rgb = img.getRGB(x, y) ^ img.getRGB(x, h - y);
				
				res.setRGB(x, y, rgb);
			}
		}
		
		return res;
	}