Japanese composers for animation are usually asked to write preliminary music based on concept art and pre-production materials. This music is released in CDs called image albums. The existence of image albums influences the creation of film music, as the composer is required to restrain inspiration within the boundaries of the preliminary music, written without concern for audiovisual relationships. Because of that, music in Japanese animation usually works as generic commentary to the moving images, without detailed forms of interaction. Studio Ghibli composers, however, have found ways to define more complex audiovisual functions by using processes of new orchestration and variation.