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Hey guys I'm writing a Quizlet flashcard pack to help people learn and memorize how the various blending modes work within the mixRGB node.

My question is, does mixRGB always handle color inputs as RGB values and not as HSV? What I mean is, blue values in Color1 are only affected by blue values in Color2, correct? Then, when each color channel has been mixed with it's correspondent, the final resulting RGB is outputed. I know that is the way it works for most of the blending types, but are there any loopholes or exceptions that I need to be aware of?

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    $\begingroup$ A brilliant idea—make sure to share it with the world when you're done (if you so desire)! $\endgroup$ – Legoman Nov 24 '18 at 23:41
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My question is, does mixRGB always handle color inputs as RGB values and not as HSV?

Yes. HSV is somewhat of a crippled colour model.

I know that is the way it works for most of the blending types, but are there any loopholes or exceptions that I need to be aware of?

Beware because most of them are display referred legacy blend modes conjured up in the dark Adobe days. The math is available in the Adobe PDF specification. They are busted up garbage in a scene referred, physical light transport system.

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  • $\begingroup$ I think in the sense you mean all color models are crippled: they are all compromises between the color space of human perception and the reproduction capability of display media. Some are better suited to printed material because they approximate the limits of ink, some are better suited to displays, since they approximate the limits of leds, for example. $\endgroup$ – Marty Fouts Nov 23 '18 at 22:09
  • $\begingroup$ No. I mean exactly what I said. The display referred model is anachronistic rubbish. Trying to make a case for it in the face of scene referred models is a fool’s errand. With particular attention to mix modes, I stated exactly what I intended; they don’t work and are broken garbage. $\endgroup$ – troy_s Nov 24 '18 at 4:51
  • $\begingroup$ I understand your statement. With respect, I dispute it. The HSV color space was invented to optimize the representation of color on a specific class of display. It's not garbage, it worked very well for the devices it was invented for nearly 40 years ago. What it isn't now is relevant. That class of devices no longer exists. Every widely used color space was developed to optimize representation on specific media, and all perform poorly on inappropriate media. $\endgroup$ – Marty Fouts Nov 24 '18 at 22:34
  • $\begingroup$ You can dispute it all you wish, but HSV (not the subject of the actual question) has several reasons existing the way it does. It’s an approximated model that has a limited degree of usage when you start cutting through it. That’s coming from someone who actually defended the implementation to be colourspace agnostic. If you do your colour science homework, you’ll also discover it isn’t a space either, it’s an encoding model. With all of that said, it deviates from the original question, which is that the mix modes are undeniably garbage with respect to the design needs that exist in Blender. $\endgroup$ – troy_s Nov 24 '18 at 23:20
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    $\begingroup$ I stand corrected, HSV is a model, not a space. We'll just have to agree to disagree on your characterization of it as garbage.' $\endgroup$ – Marty Fouts Nov 24 '18 at 23:39
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To answer your question, mixRGB always uses RGB values. HSV and HSL are alternative representations of RGB so it is always possible to use HSV to RGB conversion to allow you to work in which ever model is suitable. HSV

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