function pre() {
        pre1 = new Image();
        pre1.src='images/wedding-photography.jpg';
        pre2 = new Image();
        pre2.src='images/property-photography.jpg';
        pre3 = new Image();
        pre3.src='images/portfolio-photography.jpg';
        pre4 = new Image();
        pre4.src='images/corporate-event-photography.jpg';
        pre5 = new Image();
        pre5.src='images/free-photography-quote.png';
}