In an earlier thread, Boing Boing commenter "complicatedcrustation" wrote about a late-seventies documentary on the Belgian surrealist painter Rene Magritte, which features appropriately gloomy and trippy incidental music composed and performed by Pink Floyd's Roger Waters.
"Xeni, if you are hankering for your fix of 'early to mid-era Pink Floyd oddities' then I recommend the soundtrack to Adrian Maben's short documentary on Rene Magritte which features tons of odd sounds Roger Waters would later use in major works by Pink Floyd," BB reader complicatedcrustation says. "It sounds as if he is just mucking about, learning how to use his VC3 synth. It is wonderful!"
And that it is.
It's available on Amazon, too. From what I can tell through a quick Google, the film was originally released as "Portrait of an Artist, Volume 11: Rene Magritte."