Un-du is like magic! You can literally POUR it over your photo and it will be fine. New photos, old photos, photos from a home printer, professional photos, etc. I have never had it damage a picture. And it dries totally invisible on paper also! So if you need to remove something from a paper layout or poster, it will be fine.
FWIW..... I recently bought a little "tool" at Target called an adhesive remover. It looks like a small, round, grey eraser with a pointed end. It works great on paper.... not sure on photos............P