I am the same! I don't have kids yet (TTC), but I think about things like that already. I think when they are really wee like newborn/baby, its a bit different because they change so fast and are always in your arms/stroller/etc. but once they have really strongly unique features and are possibly recognizable and could be out of my watch (school or daycare or something), I worry more.
Maybe a cartoon type picture that reminds you of your kids or something instead? And just some of their favourite colours and things? There are always anime style pictures too, or those cartoon dolls I've seen people use. ^^