Originally scheduled for release in 1981, the double-album I'm a Rainbow was shelved at the last minute.

In the proocess, it became legendary among Donna Summer fanatics.

In 1996, I'm a Rainbow was finally released as a single compact disc.

Like most of Summer's recordings from the late '70s and early '80s, it was produced by Giorgio Moroder and Pete Bellotte, who give the stylish disco a sleek, sexy sheen.

The difference between I'm a Rainbow and its predecessors -- and, indeed, its sequels -- is the subject matter.

Throughout I'm a Rainbow, Summer turns in some of her most personal, introspective lyrics and singing, which gives the album an emotional force her albums sometimes lacked.

In fact, given the quality of the music, it's hard to see why this was shelved at the time because it is stronger than the majority of her official studio albums.