HiDPI Resolutions Disable HDR Mode Entirely

[asm-kha0z]

Hello there.
I'm using the latest BetterDisplay 1.4.10 on a Mac Mini M2 Pro (latest MacOS Ventura). One of my Screens is an Alienware AW3423DW, connected to my Mac Mini via DisplayPort 1.4 to Type-C Adapter from CableMatters. It's a QD-OLED Display with HDR support.

When using the native resolution, I can toggle the Switch for HDR within System Settings > Displays. BetterDisplay shows a ✓ for Enable HDR Mode as well. The Display is in HDR mode when the toggle is enabled (I can tell the difference visually, but the Screen's OSD confirms it as well).

ISSUE:
The problem I have is that as soon as I use any of the HiDPI Resolutions from BetterDisplay (either directly from within BetterDisplay or from within System Settings > Displays), HDR mode gets turned OFF and the HDR toggle disappears from both System Settings and BetterDisplay. Without HDR mode turned on, the Display is way too bright and the colors are oversaturated, so leaving it off is not an option.

Screenshots below.

P.S. I saw there was a bug in .8 and .9 that sounds a bit similar to my problem, but was supposedly fixed in .10

[waydabber]

It's a limitation imposed in later Ventura versions for M2 Pro systems by Apple afaik. There were some "green screen" issues before (there are some youtube videos about it). But I thought it affects only the HDMI 2.1 port - apparently this is not the case. Try lowering the refresh rate or the resolution, at some point the HDR toggle should appear.

[imkebe]

I can confirm with my M2 Pro with 3840x1600 screen using DP at 120Hz. I need to switch to lower resolution to obtain HDR. However I can use VRR and HDR 48-144Hz at LoDPI however it switches me to 4:4:2 chroma subsampling while 120Hz is maximum (DP limitation) to obtain 10bit with 4:4:4.
Also I was planning to register an issue with wrong color bit depth. Maybe this is related to our issue ? My screen is technicaly 8it + FCR however it shows in service menu that is 10bit display (needs 10bit input in HDR mode). BetterDisplay app is showing only resolutions with 8bit bpc. Anyhow related? Is your @asm-kha0z the same ?
In my case only with 60Hz I am able to use HDR and HiDPI.

[asm-kha0z]

@imkebe my Panel is a true 10-bit Panel, but I only see 8-Bit Resolutions in BetterDisplay. How did you verify what Color Depth and Chroma Subsampling is used to drive your Display? This information isn't available in the System Report of Apple Silicon Macs and I haven't found a way to verify what color depth is being used.

Could it be that Apple is not supporting 10-bit above 100Hz and therefore hiding the HDR Toggle for Refresh Rates above that? BetterDisplay is still showing me 8 bpc, but I don't know how to verify whether that's the actual color depth of the signal.

On Windows 11, I can set my AW3423DW to 3440x1440xHDR@144Hz@4:4:4 (10-Bit)

[imkebe]

Be aware that panel bit depth is related mostly to hardware of your screen. There are doubts that some LG OLED panels are in fact 8bit + FRC. It's an ability to control levels of saturation of the sub-pixels 256 vs 1024. Input signal might be 10bit however it can be 8bit + FRC. FRC just adds 2bit in time by fast changing of that sub-pixel level so in appears something in the middle for human eye.

However could you tell us if in your resolutions menu there is 8bpc or 10bpc?

Also chroma subsampling I was able to read in service menu of my screen. You cannot tell on the MacOS side since they stopped to show that for Apple Silicon devices. First I used https://www.rtings.com/tv/learn/chroma-subsampling and https://www.rtings.com/images/test-materials/2017/chroma-444.png image. If it's somehow fuzzy it's lower than 4:4:4.

Also i recomend you to try https://github.com/jursonovicst/gradient but download images and open in Finder. Browsers tends to flatten the files.

[asm-kha0z]

In my resolutions menu there is ONLY 8 bpc. However, the 4:4:4 test image looks fine at all Refresh Rates that are usable and don't produce the green screen effect on my Mac Mini (i.e. 100-144 Hz): no fuzzy text or lines on native resolution (I opened the PNG file with Apple Preview)

[waydabber]

The BetterDisplay menu shows the reported framebuffer bit depth (there are some questions about how valid this data is on Apple Silicon as it sometimes switches to 10 bits for no obvious reason by itself and there seems to be no discernable difference in quality). Framebuffer bit depth is and can be independent of connection bit depth which can differ from what the panel can actually show.

The green screen issue with M2 Pro is strange. My M1 Pro can show 3840x2160 HiDPI (so that's a 8K framebuffer) on a 4K display with HDR at 144 just fine without any artifacts, so it would be strange if M2 Pro was more limited. But there is no explanation so far for the green screen of death and Apple did seem to limit available options intenionally after initial versions probably to combat this issue.

[yarub123]

@imkebe Can you please explain to a moron like me who completely has no clue what you're talking about what I should put my resolution at, if you can. Sorry for bothering you guys, it just seems like you guys know way more.

You're right, my LG is 8 bpc but it's an HDR 4K....

Here's the thing I need help with (short post) sorry. #609 (reply in thread)

[sirkirby]

Same challenge for me on my Mini M2 Pro with an LG Ultrawide. If I stick to native resolution and bump the refresh down to 144, then HDR shows up, but to get HiDPI using BetterDisplay (text is unreadable without it), I still have to drop the refresh rate and HDR disappears. Does anyone know if this is still a limitation on the new M4 Pro?

[Rush]

I think I have the same issue. After tweaking things with BetterDisplay I lost all HDR options. Even on the Mac display on my M4 Max.