I need a PDA specifically for looking at scanned postcards.?

Hi, my father is looking for a PDA. All it needs to do is view scanned pictures of postcards so he can compare ones he has at home with ones he sees at fairs. Therefore it needs lots of memory or a SD port I guess. It needs to be able to zoom in to specific areas nnd needs to have quite a good screen - not necesarily big but clear so he can judge the quality. The PDA really doesn't need to do anything else. Maybe a spreadsheet viewer but nothin else.