If you take a look on how glue works, you'll notice two things:
- Glue pulls together smooth surfaces by an effect, similar to the capillary effect.
- Glue increases the surface between two objects by filling the unevenness of the objects.
generates a high friction and thus sticks. When you try to move an object above an surface, friction depends on what percentage of surface are facing each other. Usually, while sliding one above another, you tilt one of the objects and lower friction by that. A water film prevents the objects from tilt and even if water itself is a (weak) lubricant and lowers friction, atmospheric pressure will push the objects together (while water will pull it together) which are hard to remove without breaking the film.
Both are effects which water is capable in a limited factor, too.
So before you try anything, paying money for stuff that doesn't work, ill suggest trying water at first.
Don't make the surfaces dripping wet, but you should moisten them a little.
If you have a spray, from glass cleaner for example, spray a little, not too much, water from a longer range (like 1 meter or more).
You don't want it to be wet, but moist.
Then simply attach the picture to the moist surface, it will stick very well if not too heavy.