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This time ill show you a couple ways to get rid of the color bleeding in Vray.
First of all what is color bleeding? well color bleeding is an effect of the GI bounches in vray so that the bounched light also bounches color. so for examples if you have a white room with an red floor. the whole scene would look redish.

somethimes this is a effect we want, but not always.
So there are a couple of ways to deal with these.

Before we begin, lets show our start image :

As you can see we have a simple scene you can download it here:StartScene 
This contains a Floor, a Wall and a Ceiling and a direct light
And rendered using Very low settings for IR and Lightcashe

So lets change the floor color to a red one (RGB 255,0,0). and render it.
As you see directly for the lightcashe calculations the whole images look redish.

so here is the result:

As you can see Whowwww red
So that is a perfect example to show you a couple of ways to correct this:

Methode 1 : Adjusting the GI saturation

first is changing the renderer. in Vray goto the “Indirect Illumination (GI)” tab.
There you set the first and second bounce and such parameters. Take a look are the Saturation value (default 1.0)
Try lowering it to say about .25 and 0 and render the scenes again. the calculations for the IR and lightcash still look very red.
But take a look at the end result:

So you can see as we lower the saturation value we can controle the color bleeding. but also see what it does to the overall images (compared to the start the wall and ceilding ar much darker).

Methode 2 : Per material GI adjustments

So We are gonna try something else. set the saturation back to 1.0 
Vray has implemented a special GI material, so lets have a look at it.
Click the red material (this is an Vraymaterial). now press the material type (a button that says VrayMtl)
Choose VrayOverideMtl. and choose keep old map as submaterial.

Now if you have a look at this our Base material hase our red floor. and all the other options are blank.
Click on the button next to GI material and create here a standard vray material (color white)

Now render this one….

Well yeah, we have an red color on the floor an our walls and ceiling are nice white

So are their more methodes, well you can adjust the GI paramters per object.
Rightclick a object and choose VrayProperties. you can set here a couple of settings.
For example you can set the Generate GI to ,25 and you will see less color bleeding. but also the image will look darker.

so the methode i prefer is working with the OverrideMTL material, you have very nice controle over the bounching material.

hope this helps you guys!

Cheers

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