
Originally Posted by
Soup
Both. The structure is ambiguous that way, but context will draw the meaning out:
A: Do you have any of John's pictures? <not of him>
B: Here's one. It's of the Alps. He took it when he was on holiday last year.
A: Do you have any of John's (school) pictures? <of him>
B: Here's one. This is a picture of him in grade 9.