Saturation value from greyscale

[busseynova]

I'm using tyflow and Vray 3.6 to create a crowd simulation.

I have a lot of randomization going on using the Vray instances ID and the Vertex colour node in Tyflow. This give an RGB output (3 channels), or a greyscale output (1 channel), but I'm looking to randomize saturation too. 3DSMax composite texture uses the saturation value in its saturation mode, what I want is to be able to convert this greyscale value (from the Vertex colour) to the saturation value, for instance 0-255 Value = 0-255 Saturation.

This sounds like it might be possible with OSL maps? Or can anyone tell me another way?

[hermit.crab]

Just to be sure I understood correctly. You would like to use the greyscale vertex color information as saturation or you would like to extract the Saturation from the RGB vertex color information or both?

[busseynova]

Yes,the former. not necessarily from vertex colour, it would be great to be able to turn any 'value' figure in to a saturation or hue figure somehow.

[hermit.crab]

Sorry to say, V-Ray does not support this functionality at this point. However, we may consider including such an operator in the future builds. Otherwise, it should be possible with an OSL map.