"A picture of you and me [who are] engaged in a kiss" Of is a preposition and thus the object form of the personal pronoun is required. The me/I is not a subject and so there is no grammatical reason for I. The grammatical subject (who) has been left out.
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KooyeenIf you want good grammar, I suggest classical music.OMG! LOL! That one really tickled me. What would you recommend? Vivaldi's The Seasons?