[hardwired]

lines of different colour at different angles
An esay way to do this is to draw them in the paintComponent method of a JPanel. You can add it to your top–level container, viz, JFrame or JApplet. You may need to set a preferredSize on the panel; depends on its parent layout manager among other things.

Code:

class Pseudo extends JPanel implements Runnable {
    BufferedImage image;
    // animation variables as needed

    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawImage(image, x, y, this);
        g.setColor(Color.red);
        g.drawLine(x1, y1, x2, y2);
    }

    public void run() {
        while(boolean) {
            try
                Thread.sleep(millis)
            reassign image or change
                animation variables
            repaint
        }
    }
}

a image that may alter every 20 seconds
You can draw an image inside paintComponent and change the image inside a background Thread. Or you can wrap the image in an ImageIcon and mount it in a JLabel; a simpler way.

Code:

BufferedImage image = ImageIO.read(file_url_stream_options);
ImageIcon icon = new ImageIcon(image);
JLabel label = new JLabel(icon);
label.setHorizontalAlignment(JLabel.CENTER);
// add to top–level container