Real image width with JavaScript
// width in pixels
function setImagesWidth(id, width)
{
var images = document.getElementById(id).getElementsByTagName("img");
var newWidth = width + "px";
for (var i = 0; i < images.length; ++i)
{
if (images[i].clientWidth > width)
{
images[i].style.width = newWidth;
}
}
}