[nmstoker]

I'd second using selenium / webdriver for this. You wouldn't need a great deal of code to get the raw pixel data.

The area I suspect will need thought is how one gives "value" to distinct colours. It's tempting the go by the amount of screen space taken up, but that ignores the way the eye and mind works - a red dash in a sea of another colour needs to respect the presence of the red as it could be critical. But then there are sections where the colours might be low in importance (eg colour of text in legal text from a footer)

[paulhebert]

Yeah, that seems like a great option. I'm not sure how to get around the dithering bug that dynode ran into though. I'll have to do some research before I get started on V2