oh!  and your explanation is about what i expected _before_ double checking at CastlePoser.  without thinking about the math, i imagined a transform pretty much like you described.  and it completely threw me that it didn't seem to do that.  i'd be much happier to be wrong, in all honesty.  in this preview, the brightest color is 255, 255, 255, which is what i'd expect.  and yet confusingly asymmetrical.