Zoomify is for online use, to allow you to publish a picture that's, say, 2000 pixels wide, in a website template that's only 400 pixels wide. You're not really zooming in on the picture, you're dragging it around within those 400 pixels while viewing it at its original resolution. So unless you're publishing the picture on a website, where space is at a premium, there's no need to use it at all. And whether you're using a PC or a Mac is irrelevant, because the Zoomify software sits on the web server of the site in question.

Maybe you're right, Fraser (and thanks so much for your prompt reply; and on a Sunday evening too!). Basically it's a sort of family tree type document which can't be effectively read from a simple photograph. I was hoping that some programme could work its hi-res magic or something, and my uncle could go online and study it to his heart's content. If Zoomify isn't what I'm after, do you have any tips? And then I'll leave you alone, I promise.

I'll look into it. Thanks again.