img1src = new Image();
img1src.src = "https://www.stanford.edu/dept/its/images/seal_over.gif";

img2src = new Image();
img2src.src = "https://www.stanford.edu/dept/its/images/seal.gif";

function swapImage(){
theImg=document.getElementById("stanford_seal");
theImg.setAttribute("src","https://www.stanford.edu/dept/its/images/seal_over.gif");
}

function restoreImage(){
theImg=document.getElementById("stanford_seal");
theImg.setAttribute("src","https://www.stanford.edu/dept/its/images/seal.gif");
}