HDR mode looks horrible on Odyssey Neo G8 at full resolution

[spmp]

When in HDR mode my Odyssey Neo G8 (mini-LED as recommended) looks terrible at full resolution (3480x2160). Colours bleed badly, text looks washed out and thin, and basically the display looks like it has been upscaled from a much lower resolution source. These odd artefacts are not present when in non-HDR mode.
I am interested in HDR mode primarily to access the extended brightness afforded by BetterDisplay.
Annoyingly it all looks fine (including the screenshots) when in non-HDR mode - I will need to attach images taken with my phone if side-by-side is required.

I have tried quitting BetterDisplay and changing modes in case it was a BetterDisplay issue - no change.

I cannot use HDR mode and HiDPI when at max resolution if that makes any difference.

Are any of you, the experts, able to assist me in having a full brightness display that doesn't look terrible 8)

Also no DDC on HDMI, hoping that this will change when on DP from Alt Mode when the dock arrives...

Thank you.

[spmp]

I get better results when I use the sRGB colour profile on the monitor with one of the Odyssey G8 colour profiles from BD, essentially much lower contrast. Still not great, but better than Custom profile on the monitor. Blue is particularly bad.

[waydabber]

Does HDR content look bad on the Neo G8 on HDR mode or only the SDR content? Some displays indeed tend to produce very bad image with HDR while others are perfectly all right - I have no first hand experience with the G8.

[waydabber]

If it looks low res, then it might be using Chroma subsampling. See the Color Mode menu. If you see 4:2:2, the color resolution is halved, if 4:2:0, then quartered.

[spmp]

OH, so that makes a big difference!
Your helpful menu suggested there was another refresh rate that would allow more modes:
I dropped to 30Hz which enabled 10-bit full range in SDR mode
and 10-bit HDR10 full range in HDR more - it's better, but good to be making progress - on DP.
Is there a way to get 4:4:4 in HDR mode? And is HDR100 or more a thing? I would have thought TB4 alt-mode passthrough would have been the perfect hardware, but maybe not 8)
Also I think the display is just rubbish. Such a constant fiddle with it's colour modes which have a huge impact on text rendering and apparent pixilation + scanlines!

[waydabber]

Yes, RGB 4:4:4 is perfectly possible with HDR - if it is not available, then it might be a cable or bandwidth issue. HDR generally requires 10-bit or 12-bit (depending) connection which increases the bandwidth requirement - this is why the system must either limit the pixel resolution, refresh rate or decrease color resolution with subsampling if the bandwidth is not available for any reason.

[spmp]

Do you know what is required spec wise to support this on DP please? Where would I find why macOS has determined that the mode is not available - it looks like the dock supports all the things - but maybe not at 30Hz?

DISPLAYPORT 1.4 WITH DSC: Triple monitor USB-C docking station (MST) supports dual 4K 60Hz or triple 4K 30Hz on DP 1.4 Alt-Mode HBR3 w/ DSC enabled laptop - works with DP 1.2 supporting dual monitor 1080p @ 60Hz
...
Single Display:
4096 x 2160 60Hz (DisplayPort 1.4 HBR3 with DSC)
3840 x 2160 60Hz (DisplayPort 1.4 HBR3 without DSC)
3840 x 2160 30Hz (DisplayPort 1.2 HBR2)

https://www.startech.com/en-nz/universal-laptop-docking-stations/dk31c2dhspd

[spmp]

I hate to admit it, but mostly user error. I tried a PD-100 USB-C cable for 4K (which at the time I thought was crazy overkill), and perfect! HDR is about as good as SDR!
Serves me right for trusting the cable that came with the dock that supports... everything 8)

[spmp]

Only in HDR mode, but in strange ways. I have tried to make a text sheet to show comparison, but seems to be more pronounced on rendering in webpages etc, appears to be very contrast related. Text edges are jagged even at full resolution!

[spmp]

Should I start a separate thread for DDC?
TL;DR is detected and works in Linux using ddcutil on HDMI, not detected by BetterDisplay. Known not to be available for DisplayPort

[waydabber]

DDC over HDMI should work fine for most Samsung displays (provided you are using the built-in HDMI port or a dongle that translates I2C communication for DDC, not just for EDID - a great many of them don't).

[spmp]

Can you please advise as to how I can test this?
When connected via HDMI or usb (TB4 alt mode) ->HDMI it does not detect anything - all systems red. I tried clicking on all the input sources, but not sure what it supposed to happen, as nothing stuck...
In Linux I see three i2c devices identifying as the monitor one of which accepts DDC commands.
Still to test is whether I can use DP as the interface and still send DDC commands to the HDMI port if they are both connected to the dock.

[spmp]

OK, so DDC over HDMI works when the screen is taking input from DP 8)
Looking at 0x60, Input Source, the HDMI channel is 0x01, I tried this as the DDC input source, still no dice.

[waydabber]

It is possible then that input control simply does not work properly with the display. Not all displays support these features.

[spmp]

Sorry, should clarify: DDC is working perfectly in Linux... .oh... I think I see my confusion, I am assuming that the DDC Input Source is channel to send/test the DDC signals.
So how do I force BetterDisplay to try a particular source or whatever it is called? It's all working perfectly over in Linux land, but y'know, no gui and it's not my MBP so...

[spmp]

So now I have a good comparison between the SDR mode and HDR mode, I am not sure that I am seeing in HDR mode an increase in brightness.
In HDR mode and >100% brightness everything is pushed towards the whites, but peak brightness doesn't really change much. The screen apparently supports peak brightness of 2000cd/m2 so expecting some pretty eye watering brightness. I have turned off all dynamic things...
What is the next trick?

[waydabber]

I am pretty sure the display won't be able to produce sustained full screen 2000 nits brightness (realistically it should be about 700-800 nits). With these newer mini-LEDs usually the max SDR brightness equals the sustained full-screen white peak HDR brightness anyway. For brief moments (like flashes of light) and for smaller screen area extra brightness should be there in HDR mode, but this is mainly intended for explosion effects in games, or some smaller super-bright light sources in a game or movie scenes.

[spmp]

Aaaah, I see. I was assuming that we could play the same trick as with the internal display where HDR mode gives the opportunity to access sustained (almost) peak brightness.
In your experience which displays will support sustained >1000nit brightness? The Neo G8 has crazy scan lines and all sorts of weird, so it's likely heading back to whence it came.... Excited to restart this optimisation project 😅

[waydabber]

Hmm. Not sure. The Pro Display XDR can sustain 1000 nits. ;)

I have a a CoolerMaster GP27U here that can also seem to be able to do something near that for the fraction of the price.

Other than that I am not sure. Try reading the reviews of good candidates from https://www.displayninja.com/mini-led-monitor-list/