It is definitely Joe and me. Just leave off the "Joe". You would never say, "This is a picture of I." Also, it isn't correct to say, "This is I." For example, if someone calls on the phone and asks for you, you say, "This is she." -- not, "This is I." nor "This is me."

__________________
If this is going to be a Christian nation that doesn't help the poor, either we have to pretend that Jesus was just as selfish as we are, or we've got to acknowledge that He commanded us to love the poor and serve the needy without condition, and then admit that we just don't want to do it.

- Stephen Colbert.