[Bf-committers] Color space and alpha issues

Brecht Van Lommel brechtvanlommel at pandora.be
Sun Dec 18 22:41:35 CET 2011


You also linked to this post here, which makes a point that I didn't
fully get yet:

There is actually no right way to do color space conversion on images
with alpha, it depends on the background that they were or will be
composited over. For color correction operations it's similar, to make
it behave like painting applications it should work on key alpha, but
this isn't necessarily "right".

So perhaps there's still toggles needed to control if these operations
should happen on premul/key alpha (for image load/save, and for color
correction nodes).


On Sun, Dec 18, 2011 at 8:28 PM, Troy Sobotka <troy.sobotka at gmail.com> wrote:
> I thought I'd add the "infamous" thread over at Adobe here regarding
> associated versus unassociated alpha in the context of a system that
> needs to support various formats.
> In this case, for those unfamiliar, this was the thread in which Adobe
> responded to their (mis) handling of the EXR format.
> The players here are:
> Zap Andersson - seasoned image professional now with Autodesk.
> Florian Kainz - architect of the EXR specification.
> Chris Cox - veteran architect at Adobe.
> http://forums.adobe.com/thread/369637
> TL;DR version:
> Unassociated alpha systems cannot adequately deal with the inherent
> specifics of associated alpha systems.
> I've also added a "Further Reading" section to Brecht's page.
> Hope someone finds it insightful,
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