Do all photos need fore/middle & background?

It depends on what type of third separates the three notes.for example: if you have two mayor thirds is an "aumented chord"if you have two minor thirds is an "diminued chord"if you have one mayor first and then one minor is a "mayor chord"and inverted is a "minor chord"

The term collage was coined by both  georges braque  and  pablo picasso  in the beginning of the 20th century when collage became a distinctive part of modern art.hope this sorry if there wasn't more of an explanation!