function roll_in(imgsrc){
    document['top_image'].src = 'http://www.hydrosight.com/images/_index/' + imgsrc;
}

function roll_out(){
    document['top_image'].src = 'http://www.hydrosight.com/images/_index/orange_man.png';
}

if (document.images) {
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    img1.src = "http://www.hydrosight.com/images/_index/underwater_window_headliner.jpg";
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    img2.src = "http://www.hydrosight.com/images/_index/jana-04.jpg";
    img3 = new Image();
    img3.src = "http://www.hydrosight.com/images/_index/dicker_block.jpg";
    img4 = new Image();
    img4.src = "http://www.hydrosight.com/images/_index/dream_on_yacht.jpg";
    img5 = new Image();
    img5.src = "http://www.hydrosight.com/images/_index/tunnel_seal.jpg";
    img6 = new Image();
    img6.src = "http://www.hydrosight.com/images/_index/orange_man.png";
}