function imgreducer_swapsize (element, newsize)
{
    var oldsize = element.width;
    element.width = newsize;
    element.setAttribute ("onclick", "imgreducer_swapsize (this, " + oldsize + ")");
}

function imgreducer_inspectimgnode (node)
{
    if (node.width > 800)
    {
        node.setAttribute ("onclick", "imgreducer_swapsize (this, " + node.width + ")");
        node.setAttribute ("width", "800");
    }
}

function imgreducer_inspectnode (node)
{
    if (node.nodeName && (node.nodeName.toLowerCase () == "img"))
        imgreducer_inspectimgnode (node)
    else if (!node.style || !node.style.display || (node.style.display != "none"))
    {
        var cn;
        for (cn in node.childNodes)
            imgreducer_inspectnode (node.childNodes [cn]);
    }
}

imgreducer_inspectnode (document.body);