It occured to me recently the reason why the Compensate_For_Alpha_AA
function behaved strangely with colors > 1: emission media. Rendering the
following scene in 3.7 produces different results now than in 3.5 or 3.6
(render with +UA):

sphere {
 0,1

 pigment {rgbt 1}
 interior {
  media {
   emission .5
  }
 }
 hollow

 translate z*3
}

In 3.7 you get a fully transparent image.

The annoying thing is that mathematically it makes *sense* that you'd get a
fully transparent image, because technically the entire background is
supposed to show through. Unfortunately it's supposed to also be added to
the color of the image, but there's no way to encode that in most image
formats.

In any case, it would be good to have emission media not disappear when it's
against the background, and 3.5's behavior was good for this. Maybe its
behavior can be copied without reintroducing the color saturation bugs that
3.6 had.

 - Slime
 [ http://www.slimeland.com/ ]

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