Request to restore full ICC profile support (LUT-based display profiles) in macOS ColorSync

Our engineering teams need to investigate this issue, as resolution may involve changes to Apple's software. Please file a bug report, include a small Xcode project and some directions that can be used to reproduce the problem, and post the Feedback number here once you do. If you post the Feedback number here I'll check the status next time I do a sweep of forums posts where I've suggested bug reports.

Bug Reporting: How and Why? has tips on creating your bug report.

Thanks for the guidance. I’ve submitted the report.

Feedback ID: FB21014376

The package includes:

• ColorSyncProfileTest project
• Dummy LUT ICC profile
• Working matrix ICC profile
• Steps to reproduce
• Terminal output showing fallback ICC behavior

Let me know if you need any additional diagnostics or system traces.

Hello. I talked to engineering about your question and LUT based display profiles have never been supported on Apple Platforms.

You may wish to file an enhancement request asking for support for these types of profiles. You can file an enhancement request as a feedback report.

Hi,

Thank you for the response.

Can you please clarify the following? 1. LUT-based display ICC profiles did load and function on macOS 10.7 through macOS 13, including profiles generated by DisplayCAL, X-Rite i1Profiler and ArgyllCMS. • They were selectable in Display Preferences • ColorSync showed the LUTs in A2B0/B2A0 • Measurement reports confirmed the LUT corrections were applied • This behavior regressed starting around macOS 14 2. If LUT profiles were “never supported”, can Apple confirm: • Why they worked for over a decade? • Why ColorSync accepted them? • Why the system UI allowed activating them? • Why professional color workflows relied on them successfully? 3. If LUT profiles are now intentionally unsupported, can Apple provide: • An official statement • Updated developer documentation • Recommended alternative APIs or workflows for users needing high accuracy calibration?

Given how many professionals rely on LUT-based profiling, this is critical information.

FB21014376 Thank you.

Hi, following up on this issue. The problem persists in macOS 26.1 and the system still loads fallback profiles instead of LUT ICC profiles. Is there any update on the engineering review? Feedback ID: FB21014376

Hi @ricciohu. Thanks for asking. I have inquired with engineering to see if there is anything further we can say about this question.

Hello @ricciohu. I talked to our engineers about this question. Here is the complete story.

LUT-based ICC profiles have never been supported on Apple platforms. Previously you may have been able to provide LUT-based ICC profiles to our routines but it was a bug that our routines were not properly checking parameters and raising errors for LUT-based ICC profiles. This has been fixed in recent updates and our routines now produce errors and don't allow LUT-based ICC profiles.

Previously, using LUT-based ICC profiles with our routines produced unpredictable and erroneous results as there was no officially supported and maintained code inside of any of our routines for handling them. Any functionality you may have observed in previous Apple products using our routines together with LUT-based ICC profiles is subject to error and change without notice at any time. I do not recommend using LUT-based ICC profiles in any production code including code targeting past system software versions.

If you require LUT-based ICC profiles I recommend filing an enhancement request asking for that functionality to be added to the operating system.

Please note that filing an enhancement request does not guarantee Apple will add any requested functionality to Apple products. However, with that said, filing an enhancement request is a good way to get your ideas in front of the folks who make decisions about that sort of thing.

If you're not familiar with how to file enhancement requests, take a look at Bug Reporting: How and Why?