[HELP] How to properly identify colorspaces without the risk of failure in other versions of OpenImageIO

[milasudril]

The ColorSpace information provided by OpenImageIO appears to have changed in newer version. I would like to bump it to a newer version, but I do not want to replace the version provided by the system. The question:

If I look at the documentation v 2.4 for color space I find, among others sRGB and Linear. When I try to read a regular PNG, and a regular BMP, and a regular OpenEXR, it tells me that the two first are sRGB, and the third is Linear (as expected). However, in version 3.1, Linear is now called lin_rec709_scene. Does this mean that my app will silently break (no compile-time error or warning), when building against 3.1, or can I still test for color space linear?

It is possible that I should really run the image through OpenColorIO, but for my use-case, handling of linear and non-linear rec709 is sufficient, at least for now.

[zachlewis]

Hey there,

OIIO is moving toward (internally) using color space names consistent with the Color Interop Forum guidelines.

In the near term, we may continue internally mapping "Linear", "sRGB", and "Rec709" to "lin_rec709_scene", "srgb_rec709_scene", and "g24_rec709_display", respectively; but, for the future, the safest thing to do would be to update your app's naming as well.

(That being said, these new aliases may not be consistent with earlier versions of OIIO; depending on your app's needs and minimum-supported-OIIO, maybe you could test for both?)

[lgritz]

I know it seems like we've inconveniently changed things from OIIO 2.x to 3.0 and 3.1, but really the problem was that pre-3.0, it was incredibly inconsistent even within a single version -- whether you built OIIO with OCIO support or not, which specific version of OCIO it found at build time, and what OCIO configs were found at runtime, would all conspire to mean quite different sets of which color space names were recognized and what they meant. It was kind of a mess.

In the 3.0 era, OCIO is required (and at a level high enough to support the built-in configs), and with 3.1 we are realigning to the standard nomenclature being established by the CIF. It's pretty liberal at accepting aliases, though.