A book can have a photo in it's pages, and a photo on the front cover. On = at the surface, In = under the surface.

Generally, you would say that the photo is IN the book. "On" can be correct in some special cases, as mentioned above.

Thank you very much!

If your photo is found inside the book, then it is in the book If however you placed your photo on top of the book, then it is ok to say that it is on the book