private BufferedImage getDiceImage(int size) {
        if (diceImages == null)
            return null;
        
        switch(size) {
            case 4: return diceImages[0];
            case 6: return diceImages[1];
            case 8: return diceImages[2];
            case 10: return diceImages[3];
            case 12: return diceImages[4];
            case 20: return diceImages[5];
        }
        return null; // no image for that size
    }