// define image files and give the filenames
img1     = new Image(240,330);
img1.src = "img_2/o_pic1_ov.jpg";
img2     = new Image(240,330);
img2.src = "img_2/o_pic2_ov.jpg";
img3     = new Image(240,330);
img3.src = "img_2/o_pic3_ov.jpg";
img4     = new Image(234,330);
img4.src = "img_2/o_pic4_ov.jpg";
img5     = new Image(240,330);
img5.src = "img_2/o_pic1_norm.jpg";
img6     = new Image(240,330);
img6.src = "img_2/o_pic2_norm.jpg";
img7     = new Image(240,330);
img7.src = "img_2/o_pic3_norm.jpg";
img8     = new Image(234,330);
img8.src = "img_2/o_pic4_norm.jpg";

// change image
function changeimage(imgx,placex)  { 
    if (document.images) { 
        document.images[placex].src = eval(imgx + ".src");
    }
}