var imgWidthMax = 400;
var imgWidthSizeTo = 400;
window.onload = fiImageResize;

function fiImageResize() {
if (document.images.length) {
var docImg = document.images;
   for ( var i = 0 ; i < docImg.length ; i++)
      if (docImg[i].width > imgWidthMax && docImg[i].id != 'forumlogo') {
         docImg[i].width = imgWidthSizeTo;
      }
   }
}