How to convert RGB channel to Alpha?

[wensk]

Hi, I have a RGB texture, How to convert every individual RGB color to individual alpha color? Thanks.

[caypiranha]

hi, the amount of solutions for your answer is equal to the programmes which are capable of doing so =)

[wensk]

Hi, I konw use Photoshop to split every channel, But in 3dsmax material editor, how to use Vray turn the RGB to Alpha?

[caypiranha]

Hi, ah haven´t used it from this aspect. I used channel splitting only for output/compositing reasons created by multichannel renderelement.
Mainly I collect all any channel-relevant objects as a quickselection set. In the Multichannel settings you can add those selection sets then to any RGB channel.
In Photoshop of course you get them all as "alphas" in the Channel list as well, where you can collect as many masks as needed. (regarding to the number of multichannel layers used by the render output.)

[Joelaff]

You can use Max's Color Correction node for this. Or VRayPluginNodeTex has a Color Correct and Color Correction that can do it too.

[wensk]

Hi, Joelaff

Thank you for help, but the diffuse color seems don't correct, it too white. I used Alpha= red , and Alpha = red(inverse).

[wensk]

Oh, my mistake, aftewr adjust the map value to white, the problem solved, Thank you Joelaff !

[Joelaff]

Oh, you got it? Good. I see why you needed alpha now.

And I never did understand why those blend colors in the VRayBlend default to grey, rather than to white? It confuses me much of the time.

[wensk]

Haha, I'm also think so.

[Joelaff]

I am curious if anyone has done any render time tests to find the fastest way to do this channel shifting, though. Color Correction always seemed like a heavy node to do something so simple. Would prefer a fast, simple VRay version. Maybe those PluginNodeTex versions are faster since they let you enable and disable different sections, but with modern processors it is weird how sometimes branches slow things down so much, that it is faster not to use the conditionals (like if branch prediction thinks it goes one way, but it really ends up needed to go the other way).