Display grid over background image using JLayeredPane.

gridImageLayer

JLayeredPane layers = new JLayeredPane();
layers.setPreferredSize( new Dimension( GRID_SIZE, GRID_SIZE ) );
layers.setLayout(new FlowLayout());

BufferedImage backgroundImage = null;
            try{ backgroundImage = ImageIO.read(new File("resources/Background.png"));}
            catch(IOException ex){
                System.out.println(ex);
            }

JLabel bImage = new JLabel(new ImageIcon(backgroundImage));
JPanel grid = createGrid(); //creates a grid the same size as the image (500,500)

grid.setBackground(new Color(0,0,0,125));

layers.add(bImage, new Integer(1));
layers.add(grid, new Integer(2));