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how can I extract color from texture

Message 1 of 13
613 Views, 12 Replies

how can I extract color from texture

Is there a simple way to extract color from a texture in orderr to use it as mask in a layer shader? I've serched the forum and web but I coudn't find a solution. Thanks

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Message 2 of 13

Don't the blending_mode or alpha operations of the layer_RGBA get the effect that you want to achieve? What is the effect that you are trying to achieve?

Lee Griggs
Arnold rendering specialist
Message 3 of 13

I’m using some jsplacement maps in order to simulate a motheboard. I’d like to isolate color from the texture in order to use as mask and apply different shader via layer shader.
Now I’m using photoshop to select color and create texture to use as mask. I was wondering if there is a simple way without using photoshop.
thanks again

Message 4 of 13

In Arnold I’ve tried with the ramp but I cannot achieve a perfect result.

I’ll post some images if needed.

Message 5 of 13

Yes, LayerRGBA should work for that.

Lee Griggs
Arnold rendering specialist
Message 6 of 13

I know that layer shader is the correct way. I was asking about the possibility to create masks directly in Arnold without using photoshop.
thanks in advance

Message 7 of 13

The attached file explain what I'm trying o achieve in arnold. perhaps usin a ramp node in association with some others nodes.


Message 8 of 13
in reply to: guglielmo_natuzzi

This is easily done if you can code a bit of OSL.
Filters can be extracted at any level, with any combination of levels of grey as a base.
You can use something like if statements to capture data.


else if
else if 
Message 9 of 13

Thanks a lot for your reply. But I have any knowledge of the osl languages.
I thought there was an easiest way.

Message 10 of 13

Here is what I get using layer_RGBA.operations.


Lee Griggs
Arnold rendering specialist
Message 11 of 13

A step further.
thx a lot.
i’ll try this solution

Thanks again


Message 12 of 13

I've tried the suggested workflow but I was not able to isolate and mask part of the texture based on the color.the blending mode you suggested is omogeneusly applied to the whole texture.

Where is mi mistake?


Message 13 of 13
in reply to: guglielmo_natuzzi

This would be extremely useful. There are lots of ways to generate color data, and few ways to PICK a color from the data and manipulate it specifically. This is pretty much how post works, but theres no reason not to have this functionality at the material level. Being able to procedurally or dynamically generate masks is more efficient use of time and optimizes hardware resources come render.

I'm also trying to crack this egg. I want to use cryptomatte or AIUtilities > Object/ObjectID outputs as masks to limit projections to spcific areas of a subject. Making multiple materials for various parts, or creating numerous RGB masks is a complete time sync when the data is right there!

We want to be able to hand it any image, color pick any RBG value, and the output results in a black and white mask. Color picking is important as its unrealistic to manually determine and enter every value when we want to use this functionality.

Absolute perfect implementation would be using a cryptomatte enumerator that just listed the objects and you can add or remove them from a mask set. This is how nuke interprets the data, I just want to use it way before comp.

Any help would be greatly appreciated!

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