What’s an image album?

What I initially thought was that an image album contained music made by the composer prior to the film’s (or series’) completion, which may or may not have made it into the film in some form or the other. So sort of a look into the composer’s sketch book.

But reading this (http://en.wikipedia.org/wiki/Image_album), it would appear that I’m completely wrong, and that an image album is simply a tie-in album; music somehow related to the film but which wasn’t in the film.

Could anyone shed any light on what an image album is or isn’t?

What I initially thought was that an image album contained music made by the composer prior to the film’s (or series’) completion, which may or may not have made it into the film in some form or the other. So sort of a look into the composer’s sketch book.

That sounds more like a sort of "concept" album or something. You know, like they have the concept art for games, of the original ideas of characters and places and stuff like that. http://en.wikipedia.org/wiki/Concept_art