img0_on = new Image(256,94);
img0_on.src="img/pt_on.jpg";
img0_off = new Image(256,94);
img0_off.src="img/pt_off.jpg";

img1_on = new Image(256,94);
img1_on.src="img/ot_on.jpg";
img1_off = new Image(256,94);
img1_off.src="img/ot_off.jpg";

img2_on = new Image(452,143);
img2_on.src="img/lbjj_on.jpg";
img2_off = new Image(452,143);
img2_off.src="img/lbjj_off.jpg";

img3_on = new Image(520,127);
img3_on.src="img/cajon.png";
img3_off = new Image(520,127);
img3_off.src="img/cajoff.png";

function over_image(parm_name)
     {
        document[parm_name].src = eval(parm_name + "_on.src");
     }
function off_image(parm_name)
     {
        document[parm_name].src = eval(parm_name + "_off.src");
     }