Do you know a webpage appearance comparator?

Question

I need a tool to compare the design of a website, I do not want to compare the HTML code only, but the output design.

Is this even possible? also is there any openso

Answer 1

There are these online tools - that aren't brilliant:

http://www.w3.org/2007/10/htmldiff

http://www.aaronsw.com/2002/diff/

I like the look of daisydiff but have not used it in anger: http://code.google.com/p/daisydiff/