public void paint(Graphics g){
        setShowPicture();
      for(int i=0;i<getHeight();i++){
        for(int j=0;j<getWidth();j++){
            
            //for size -1 to 1
            double x = ((((double) j) / getWidth()) * 2.0) - 1.0;
            double y = ((((double) i) / getHeight()) * 2.0) - 1.0;
            
            double redExp =   red.randomFunction(x,y);
            double greenExp = green.randomFunction(x,y);
            double blueExp =  blue.randomFunction(x,y);
            
            // before plus 1, the result is 1. ..
            // after plus 1,make it <= 1
            g.setColor(new Color( (int)((redExp+1)*255/2), (int)((greenExp+1)*255/2), (int)((blueExp+1)*255/2)));
            g.fillRect(j, i, 1, 1);
            
        }
      }
       
    }