My son and I having fun or My son and me having fun [duplicate]
How about: forget all the qualifiers, what if you just take a self-portrait and title it "I"? What about "Me"? (What about I, Robot? I, Claudius?) I think, the latter usage aside, the point is that a work of visual art in particular is understood to be quite literally an object (an "art object"), and the pronoun should be accusative (me). I would suggest that the implied sentence is "This is a picture of ___." (In a bit of a syntactical nightmare, we call the thing objectified "the subject," but ignore that. :-) )