And my sincere opinion here is that if you want to determine the effective size of an image on the browser screen, there are many factors which influence this. (And yes, I hadn’t even considered CSS.) Sure, all these tools exist for getting to the HTML, etc., but that’s only the tip of the question being posed as I read it. There are so many potentially influencing variables here, apart from the HTML itself, that the objective is at best difficult to answer. I found the question as-stated to be vague, as in, difficult to ascertain what potential factors were intended to be in-bounds or not. Getting to the HTML and/or CSS elements in Perl, fortunately, is a technical matter that has been very-well solved by CPAN.