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Hi,
I'm using Cinema4D R17.055 and Octane 3.03.4-R3 and I have an issue using an Xpresso tag to control the diffuse color of a Octane material.

I got 2 materials: the first diffuse color is a RGB value that I can choose, the second diffuse color is controlled by an Xpresso that take the color from an user data. When I choosed the same color from the first diffuse color material (using the color picker) from the user color data, the second material appears brighter than the first. Is this a bug? Is it my fault? I don't understand. You can find the scene at this link: https://1drv.ms/u/s!AjYjAZhvVLBEgblVc85VNuEgY_btog

I don't understand what you do but check image. It explains how works the color system. There is a Linear<->SRGB conversion and it depends to your scene color profile.
So simply you can't give picked values to color values for SRGB color profiles.

Hi Aoktar,

I'll try to explane this in a different way, for example if we need to choose some colors from a styleguide, they are in rgb format, or hex code, usually we pick the value from photoshop, with the picker of c4d, and it works well in both c4d or octane materials, in this case we need to pilot some materials colors from an user data node, linking in Expresso the outpout rgb values of the user data, to the input rgb values of various octane materials, so we can control those all in once from one single node, this works flawless in c4d, but as you can see from the example here: in octane the output values differ, 0 is 0, and 255 is 255, but the conversion of the value inbetween is wrong (or, maybe it work by default in different way, but the result is wrong) there is a workaround to resolve this issue?
thanks for your reply
A.

Did you checked my explanation?
Simply you need divide colors to 255 and apply a SRGBtoLINEAR conversion.

Hi!

thanks Aoktar, we'll try this solution, let you know if it work