Displaying different categories of images on detail page

I’ve set up a listing page for an artist that displays a thumbnail and category title for a number of different categories of her artwork.

http://www.terrerybovich.com/drawinglist.php

All of the categories use the same size thumbnail for the listings page, but each category needs to use a different size thumbnail when displayed on the details page.

I’m using the first thumbnail size for the list page.

So far, I’m using thumbnail 2, 3 and 4 and a series of if statements to determine which category of images will be displayed on the details page.

Up to now this has worked fine, but when I get to group number 4, I’ll be out of thumbnails and the plan will fall apart.

There must be a better approach.

Any suggestions?

Thanks,

Jerry Kornbluth