Years ago my Grandfather had a picture of his tree farm above his fireplace. This picture seemed to be a transparency of sorts, yet from a distance appeared to be just an average picture. The picture was in a frame about an inch or two thick. When he turned on a switch on the frame, a light between the pic and the back of the frame backlit the entire picture making for a very bright illuminous picture. I would like to know what this procedure is called and where can a person begin looking to have something like this done and what it involves. Thanks.