Expand sRGB color space

Discussions - Using ACES Video Games
1

Hello. Due to legacy reasons my code base working color space is sRGB. I’d like to make it possible for artists to pick colors outside of this color space, as you can imagine, changing working color space to another wider one means lots of changes and tons of work.

Let’s say in our color pickers I provide colors outside sRGB color space (the colors will clip when displayed in color picker), when is time to display the game rendered image, can ACES take these out-of-srgb colors and map them within the srgb range? Do I use the ODTs found here?: aces-dev/transforms/ctl/odt at dev · ampas/aces-dev · GitHub

Thanks!

2

Hello and welcome to ACEScentral !

As you will most likely find in the code, the ODTs also clip out-of-gamut values.

// Handle out-of-gamut values
// Clip values < 0 or > 1 (i.e. projecting outside the display primaries)
linearCV = clamp_f3( linearCV, 0., 1.);

May I ask you why you want to go to a wider working/rendering space and what are you trying to achieve ? Out of curiosity ?

I have given it many thoughts and many tests to finally set the working/rendering space of our movie to linear_rec709.

Regards,
Chris

3

Am trying to give our artists the ability to use rec2020 colors, as it stands today, rec709 is all they get with our tools, even when the game renders in an HDR monitor. I guess what am trying to solve is how can I provide our artists the ability to use HDR colors without having to make a ton of changes. I thought that by allowing them to step out of the working gamut, ACES could take those out of range srgb values and some how do gamut compression. At the same time, those out of working gamut values would map well within the rec2020 color range and therefore allow the aritsts to use rec2020 colors as well. Let me know if this makes sense.

4

Hello and sorry for the late reply,

I think what you describe is what the Output Transform Virtual Working Group is currently trying to achieve for ACES 2.0 with Gamut Compression and such.

What you could look into if you want to expand the color palette of your artists is the OCIO role “color_picking” as implemented in Autodesk Maya. Maybe ? Or just switch the OCIO role “scene_linear” to P3 or BT.2020 with the usual issues. Are your HDR monitors really Rec.2020 ? I am not sure if they can reach 100% of this gamut yet.

To be honest, I haven´t seen a single Display Transform that does not clip or skew at some point with wide gamut… Maybe AgX will do that someday. This is why I switched back to BT.709 until someone solves this riddle.

Chris