image1 = new Image();
image1.src = "images/icon_ind.gif";
image2 = new Image();
image2.src = "images/icon_indh.gif";
image3 = new Image();
image3.src = "images/icon_cor.gif";
image4 = new Image();
image4.src = "images/icon_corh.gif";

function move_in(img_name,img_src) {
document[img_name].src=img_src;
}

function move_out(img_name,img_src) {
document[img_name].src=img_src;
}