HDR looks washed out on LG UltraGear 34GP63A-B with MacBook Air M4

[RandomNGuy87]

Hello, I have a MacBook Air M4 and an external LG UltraGear 34 monitor, model 34GP63A-B, and I’m having issues with HDR looking washed out and dull.
The monitor is connected from the Thunderbolt port to DisplayPort, using a good-quality UGREEN cable. The colors are set to 10-bit full range, the resolution is HiDPI, and the monitor’s color profile is selected, so the image looks very good in SDR. However, when I enable HDR, all colors become washed out and lose contrast. I’ve already tried changing several monitor settings and adjustments, but the colors still look bad.
Does anyone have any suggestions, or has anyone experienced something similar?

[waydabber]

Well, it's a typical problem.

You can compensate to some extent by choosing a narrower color profile for the display (for example sRGB instead of Display P3) as that will increase the apparent saturation.

An other option is to turn on "Enable compositor filter layer" under "Advanced control settings" (on Tahoe) and then use the saturation slider under Image Adjustments. This may however affect rendering performance in current macOS Tahoe versions.

A third, somewhat trickier solution is to override the display's EDID and adjust chromaticity and colorimetry settings. By overriding chromaticity, you can redefine the gamut triangle which will affect apparent saturation. The color can be further depend on Colorimetry settings and the supported EOTF configured in HDR Static Metadata. But adjusting the EDID is a complex pro level stuff and requires a lot of experimentation to make things right.

You can try playing with these in the display's EDID + make sure you force recreating the factory profile in macOS every time you change something.