I would dry-mount the photo to a piece of mat board or foam core board and then hot melt glue it to the wood slats.
Hi Debbie. I'm Cindy. You could use Mod Podge for this project. The wood slice should be dried out and then sanded. Use a foam brush and apply the Mod Podge on to the wood. Then put your photo on top of that. Then smear the entire surface with Mod Podge again. Debbie, perhaps you should use a color copy of the picture you intend to use. That way you will not harm the original. Best wishes coming your way.