Difficulties picking colours - something is not right Tweet

[juanjgon]

Of course all Octane color settings are set to linear (gamma 1.0, response linear) ... if not of course the color that you pick in any LW color picker can't match the color you get in Octane, because plugin can't correct the color of the LW color picker. LW color picker doesn't know anything about film response or any other tone mapping functions that Octane has.

In resume ... LW color picker is working in linear color space, if you are rendering using Octane tone mapping functions (a film response, for example), color doesn't match because LW color picker doesn't know what is a film response.

Perhaps Standalone perform a tone mapping of it's color picker, I don't know ... but for example if you pick a 0.2 gray in LW, you only are going to get a 0.2 gray color in Octane if all Octane color settings are set to Linear.

-Juanjo

[gordonrobb]

I am totally confused then. I get what you are saying (I think). The colour that the picker is showing is as it should be (in linear), and if I set the Imager to liner with no camera profile, that is the colour I'll see. All great and physically accurate and all that. However, unless I'm missing something, totally useless for picking a colour as you'll see it. Don't people pretty much always view/render with a colour profile?

In the standalone, the default setting has the colour picker show pretty much the right colour for an image in gamma 1, but with a colour profile. If you set the imager to linear/off then the colour picker does not match what renders. I would imaging that people expect to be able to select a colour (unless they are working with a known RGB level) based on what it looks like.

If I set LW to sRBG (when not using Octane), the colour picker shows the colour that is rendering. I'd be interested in what other people think, but I would like to for the picker to match the profiled render (as it is in standalone) or at least have the choice.

[juanjgon]

Yes ... I understand your issue. You want a color picker that support the Octane tone mapping functions to match the picked color with the color you get in the render after the tone mapping, but I am not sure if this is even possible.

But Octane Stanalone also show this behavior ... see this example, I set the Imager to gamma 2.2, film response Gold 200. A diffuse material with 0.1 gray in the node settings render a 0.48, 0.44, 0.40 color object. Doesn't match at all.

-Juanjo

[juanjgon]

Of course, the same Standalone scene with the Imager settings set to linear (gamma 1.0, film response linear) render the object with the 0.1 gray of the surface node.

-Juanjo

[gordonrobb]

You're right that if you increase the gamma from 1 and add a response profile that affects the colour it is off. But with the default of Gamma 1 and Agfacolour 100 it is at least a similar brightness. My assumption is that the colour picker is in sRGB (changing it in the preferences doesn't seem to change it).

It's possible to do it in LW native as I said, if you have CS set to sRGB, the picker matches the render.

Maybe it's me. If you're telling me it's working the way it should and that nothing can be done to have it behave more like the stand alone setup, then I guess I'll work round it.

[gordonrobb]

Of course, the same Standalone scene with the Imager settings set to linear (gamma 1.0, film response linear) render the object with the 0.1 gray of the surface node.

-Juanjo

Try Gamma 1 and gold 200, brightness is similar, it just has changed the hue slightly. I wouldn't change gamme from 1 in the Imager normally.

[juanjgon]

I think that currently the plugin can't correct the color picker using the LW color profiles. But this could be possible ... I will try to add this feature, this perhaps could help with your workflow ... a sRGB color picker could help if you are working with Octane tone mapping.

This thread is really interesting ... the color management is something really complex, and more if you need to exchange data among applications.

Thanks for your reports

-Juanjo

[gordonrobb]

No worries. I'm not a professional so it may be entirely possible I'm doing it completely wrong and I shouldn't expect it to do this. I was only asking because it was the default behaviour of standalone.

[COBRASoft]

Thanks for all the research guys. I'm trying some stuff too now. And the specular is also important it appears to me.

[gordonrobb]

I was just wondering if there had been any movement forward with this.