I think the idea of using the painting instead of a camera picture helps to clarify it a bit. While I have no expectation of privacy in a public space, I would expect to have my wishes to have my picture taken or not respected. I doubt I would be give that respect, yet I desire it. Again, in a private setting it is more about boundaries and respect. I would want to be asked, especially now that so much is posted on line with tags and such that I might be searchable. I would expect my family, friends, or guests to respect my desires, but I doubt it is legally enforceable.
Recently I was in Santa Fe. A large number of Native Americans were on the square selling arts and crafts. So many of them had beautiful faces with a lot of character, but they almost all asked their picture not be taken. I went out of my way to always ask and respect their wishes as I know that is a sensitive cultural issue. Does anyone ever deserve less respect then that?