feature request: Gamma option on RGB_Spectrum_Texture

[Wenneker]

I often use colors in the diffuse slot instead of textures. It would be really nice to either have a separate gamma node or a gamma option in the RGB_Spectrum node. That way it would be a lot easier to pick the right color.

[prodviz]

How are you picking accurate colours at the moment?

Are you picking the colour you want, and then (edit) dividing by 2.2 to get the colour?

[Wenneker]

Most of the time I just pick something that I think is close to what is needed and tweak untill it looks good in the interactive renderview.

For those occasions where I really need a specific color I type them in from another app, ie Fusion or photoshop.

[prodviz]

Cool, cheers.

The old skool way of dividing every RGB value by 2.2 seems to work.

A little laborious for each and every swatch - a Gamma setting in the colour would be cool.

[roeland]

The old skool way of dividing every RGB value by 2.2 seems to work.

OK, that is weird—dividing by 2.2 does not at all do a gamma correction. It just makes the colour darker.

Just for reference:

The color picker may give you the RGB values in the sRGB colour space. That's a widely used colour space, and closely approximates a 2.2 gamma value for intensity.
For instance suppose you pick (255, 128, 0) or #ff8000:
If you interpret these values as linear values it will look like this:



Note how the colour not only becomes lighter, but it also looks more yellow.

I don't know how colour management in Maya works, but if the colour picker displays the more orange colour when picking (255, 128, 0), and the rendered image from Octane then shows the more yellow colour, then this is likely a problem we need to fix in the Maya plug-in.

--
Roeland

[prodviz]

Thanks for the info, Roeland.

Here is the setup in Maya:


The swatch and the render look the same, but the colour in the picker has the darker orange.

[prodviz]

Yep, like you say, the colour looks to be in Linear space, as this is the Linear output:



So would it be the right thing to have a Gamma switch on the colour/RGBSpectrum node?
Or should the swatch colour change and update depending on which space you have set?

[Wenneker]

I would prefer a switch on the color node.

also while you're at it.. Is there a way to get the color to show up in the maya viewport? maya2015 only shows everything with a gray color when viewport 2.0 is enabled.

[prodviz]

I haven't upgraded to 2016 yet, but this conversion table looks handy:

http://davengrace.com/cgi-bin/cspace.pl

Looks like you enter the top row for the colour you're after and the 3rd row is the value for the swatch.

[prodviz]

Ah, just realized the Maya Gamma node plugs in to the Octane RGB node. Solves the lot