function ch(imgsrc) {
    e = (window.event) ? window.event : e;
    var target = (window.event) ? e.srcElement : e.target;

    if(imgsrc != "undefied") {
       target.src = imgsrc;
    }
}

var pic_over = new Image(513, 179);
pic_over.src = "images/pic_color.jpg";

var pic_out = new Image(513, 179);
pic_out.src = "images/pic_grays.jpg";

d = window.document;