Are there any JavaScript or jQuery APIs or methods to get the dimensions of an image on the page?
it is important to remove the browser interpreted setting from the parent div. So if you want the real image width and height you can just use
$('.right-sidebar').find('img').each(function(){
$(this).removeAttr("width");
$(this).removeAttr("height");
$(this).imageResize();
});
This is one TYPO3 Project example from me where I need the real properties of the image to scale it with the right relation.