private void constructImage(){
		Graphics2D g = (Graphics2D)image.getGraphics();
		g.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
		g.setColor(Color.black);
		g.fillOval(0, 0, width, height);
		
		g.setColor(Color.white);
		g.setFont(new Font("Arial",Font.PLAIN,height-10));
		String str = ""+number;
		g.drawString(str, width/2-g.getFontMetrics().stringWidth(str)/2, height-10);
	}