[Bf-compositor] Question regarding changes to blending modes

[Sean Kennedy]

Hmmm, some of those changes on the demo page are pretty drastic. I've always thought that blending modes were a defined calculations, so they'd be the same everywhere (Blender, photoshop, after effects, nuke, everything...). If that's true, and updating them causes a major changes in the resulting image, were they broken before? Are they fixed now? Which way is the "correct" way? That's the way I would vote for.
Hope that makes sense.
Sean

Date: Thu, 5 Jun 2014 17:05:27 +0200
From: kevin.dietrich at mailoo.org
To: bf-compositor at blender.org
Subject: [Bf-compositor] Question regarding changes to blending modes



Hi people,

 

I'm currently writing a patch to rework the state of blending operations inside of Blender. Right now the operations are defined in multiple places around the code base so I thought it could be good to ease out maintenance of that part of the code and to have them all defined in one place. So far, so good.

 

By running some speed-tests, out of curiosity, I noticed that (at least in the compositor) the Hue, Saturation, Color and Value modes were the slowest. And that is apparently due to multiple RGB <-> HSV conversions. So I did some searches and found some interesting simple formulas which do not rely on those conversions.

 

Now, these modes are a little faster (~10-12%), but they do look a little different than before, especially the Value blend mode(, and that is a little strange).

 

So the question is: would the users (especially module members) agree on that change ?

 

To have a look at the patch, or to test it, or just to see the difference between the before and after for those above mentioned operations, please head over to  http://developer.blender.org/D539 .  I have uploaded there a few images demonstrating the changes.

 
Sincerely,
 
Kévin Dietrich.


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