Ultrawide brightness and resolution

[roguefury]

Hi,

I'm in the market for an ultrawide monitor and just received the LG 34WP88C-B. After plugging it into my MacBook Pro, I was disappointed with the monitor's brightness and resolution. This is a curved monitor (which wasn't a requirement for me, I could have gone with flat). I tinkered with using USB-C and HDMI, but that didn't make much difference. I'm planning on returning it.

So...what have others experienced with brightness and resolution with ultrawides? Am I just spoiled with Macbook Pro and iMac (5k) brightness and resolution?

Any other monitor recommendations worth considering?

 

[Amethyst1]

The LG 34WP88C-B only has about 110 ppi, which causes fuzzy font rendering in macOS.

An ultrawide that has a sufficiently high pixel density (≈163 ppi) to make macOS enable the HiDPI modes with their vastly better font rendering out of the box is the LG 34WK95U with a 5120×2160 resolution.

 

[roguefury]

The LG 34WP88C-B only has about 110 ppi, which causes fuzzy font rendering in macOS.

Thanks, makes sense. Oof, that other LG is super expensive.

 

[joevt]

disappointed with the monitor's brightness and resolution

The 1440p height should have been a give away. I still use a 2560x1600 display from 2005 but for anything new I wouldn't go with less than 4K 16:9 (I do have a few 4k displays and a 5K)
If you're a gamer then 1440p is fine but in that case you would be using a PC.

Sadly, if you want 10Kx2880 (a double wide 5K display instead of a double wide 1440p display) you'll probably be waiting a long time. Such a display would probably require HBR3+DSC - more than what can be done using Thunderbolt without DSC and more than two separate HBR3 connections (if you also want HDR).

Or maybe DisplayPort 2.0 will exist?

 

[Amethyst1]

8022×3384, i.e. 6K ultrawide, on 40" (for ≈218 ppi) sounds like it might be fun too.

 

[joevt]

8022x3384 (ie. 6K ultrawide) on 40“ (218 ppi) sounds like it might be fun.

That 8K3K is the same ratio as the 5K2K (21.3:9). It's less pixels than the 10K3K (same ratio as the 5K1440p 32:9) that I was suggesting.

Now, a 12K ultra wide would be even more interesting (12032x3384 32:9 12K3K). That could only work if DSC can do 9bpp or less. Right now, according to AGDCDiagnose output, I believe Apple usually uses DSC to compress 12bpc to 12bpp. 12bpp is the max that can allow 6K60 at HBR2 link rate. Only 10bpc is required for HDR. Can DSC do 10bpc->9bpp? Should look at the DSC source code on the VESA web site to find out:
https://app.box.com/s/vcocw3z73ta09txiskj7cnk6289j356b/folder/17917732557
The page at https://vesa.org/vesa-display-compression-codecs/ says DSC can do 10bpc->8bpp so 12K3K should be fine.

 

[Amethyst1]

Now, a 12K ultra wide would be even more interesting (12032x3384 32:9 12K3K).

What about a 16K ultrawide, ie. 15360×4320?

 

[joevt]

What about a 16K ultrawide, ie. 15360×4320?

Probably doable since DSC is supposed to allow 8K120? Checking numbers...
16K4K requires 4116 MHz using CVT-RB2 at 60Hz. That would require DSC to do 6bpp at HBR3 link rate. I think DSC is limited to 8pp? Maybe 4:2:2 can be added on top of DSC?

The DisplayPort wikipedia page says DSC + 4:2:2 can allow 8K120 8bpc at HBR3 link rate. 10bpc requires DSC + 4:2:0.

 

[Amethyst1]

Oof, that other LG is super expensive.

The MSI PS341WU is also a 34" 5120×2160 ultrawide. Perhaps you can get that for less than the LG? It's not exactly cheap either though.

One thing you could try if your MacBook Pro is an Intel one and of the "Late 2013" or newer generation, as a workaround of sorts, is to use e.g. SwitchResX to create a custom scaled HiDPI mode, such as 2752×1152, for your 3440×1440 monitor so that you sacrifice some real estate but do get the vastly better font rendering that the HiDPI modes provide in return. I have a 27" 2560×1440 monitor kicking around (≈110 ppi, like a 3440×1440 ultrawide) and when I use it with a modern version of macOS, I use a 2048×1152 HiDPI mode. That makes fonts bearable. It's no match for a proper high-PPI display but still better than the "OOTB experience".

 

[roguefury]

My temp solution is to use Luna Display with Thunderbolt into my 5k iMac. Comparing to the ultra-wide, the screen display on the iMac is remarkably crisp, albeit not exactly speedy (some latency on moving windows around). This will do until I figure out what to do next.

 

[Amethyst1]

My temp solution is to use Luna Display with Thunderbolt into my 5k iMac.

So the iMac serves as a secondary display to the MBP? Do you get 2560×1440 HiDPI on it via Luna Display? (I ask because this didn’t work/wasn’t supported when I still had mine.)

 

[roguefury]

So the iMac serves as a secondary display to the MBP? Do you get 2560x1440 HiDPI on it via Luna Display? (I ask because this didn’t work/wasn’t supported when I still had mine.)

Yes, the iMac is serving as the secondary display (I'm using it right now). I'm getting 3200*1800 on the iMac.

My long term plan is to migrate the iMac (intel) over to a mac mini and then get a monitor that can do dual duty for me. But, in the meantime, Luna is serviceable.

 

[Amethyst1]

I'm getting 3200*1800 on the iMac.

HiDPI I presume?

 

[roguefury]

HiDPI I presume?

Yes, and no. I am getting full resolution on the iMac via Luna, but it's not as clear as from the native iMac. There's some granularity. That's made up, however, by the full brightness. And, like I mentioned before, it's surprisingly serviceable for using productivity apps like O365 and MS Teams (while running video calls).

 

[Amethyst1]

I am getting full resolution on the iMac via Luna, but it's not as clear as from the native iMac.

That doesn't sound like HiDPI. Can you take a screenshot of the System Profiler's Graphics/Displays section on the MBP with a Luna session to the iMac going on?

 

[roguefury]

Here's a screen grab

 

[Amethyst1]

Here's a screen grab

Thanks a lot. No HiDPI (if it were HiDPI it would say 6400×3600 for resolution). So they still haven't enabled HiDPI for iMacs as secondary displays yet, just for iPads (and maybe MacBooks?).

 

[roguefury]

Thanks a lot. No HiDPI (if it were HiDPI it would say 6400×3600 for resolution). So they still haven't enabled HiDPI for iMacs as secondary displays yet, just for iPads (and maybe MacBooks?).

I guess not. Maybe that's a limitation of the processing power or dongle? If they went all the way to HiDPI, that would be cool

 

[Amethyst1]

Maybe that's a limitation of the processing power or dongle?

Processing power and network speed maybe. I have an unconfirmed feeling the dongle is just a glorified dummy monitor simulator of some sort.

 

[roguefury]

I remember reading that the dongle was to emulate HDMI out, or something like that.

 

[Amethyst1]

I remember reading that the dongle was to emulate HDMI out, or something like that.

Yes, that’s what I mean.

 

[joevt]

Thanks a lot. No HiDPI (if it were HiDPI it would say 6400×3600 for resolution). So they still haven't enabled HiDPI for iMacs as secondary displays yet, just for iPads (and maybe MacBooks?).

Luna Display documentation is not informative.

Doesn't Luna display behaves like a real HDMI display? Isn't it macOS that's responsible for enabling HiDPI? macOS shouldn't know the Luna display is connected to an iMac. So I don't understand why HiDPI wouldn't work.
https://help.astropad.com/article/189-mac-to-mac

Does Luna display support larger frame buffers are lower refresh rates? Can it do 5K at 39Hz (should fit in HDMI bandwidth limit)?

I don't see why it couldn't output a "Looks like 3200x1800" HiDPI mode @ 4K (6400x3600 framebuffer). The GPU does the scaling work for Luna Display like it would for any display. This is true only if the Luna display dongle was receiving the HDMI data and transmitting that. But if they have software doing the work on the Mac then the large frame buffer would slow things down. It seems that the latter is true - because they require Screen Recording to be enabled. In that case, the Luna Display dongle is just a useless dummy HDMI dongle and uses up your Mac's CPU performance?

I would use SwitchResX to create some custom timings that could work via HDMI and test them through Luna display:

timings:
4K 60Hz
5K 39Hz

scaled modes:
6400x3600
6016x3384
etc.

 

[Amethyst1]

Isn't it macOS that's responsible for enabling HiDPI?

Yes, but doesn't it only do that automatically if the display's resolution is high enough? If Luna reports e.g. 3200×1800 as maximum macOS might not enable HiDPI automatically. When I had an actual 9.7" 2048×1536 (264 ppi) display connected via DisplayPort I also had to manually enable HiDPI.

But if they have software doing the work on the Mac then the large frame buffer would slow things down. It seems that the latter is true - because they require Screen Recording to be enabled. In that case, the Luna Display dongle is just a useless dummy HDMI dongle and uses up your Mac's CPU performance?

Luna requires software on both the main and secondary machine. It definitely has an impact on the main machine's CPU. Their forums seem to have disappeared but someone had posted a picture of the dongle‘s internals - there was basically nothing in it, just a single tiny chip IIRC.

 

[joevt]

there was basically nothing in it, just a single tiny chip IIRC.

Probably a chip for the Luna Display EDID. Basically, macOS sees the Luna Display EDID through the GPU and creates a normal GPU accelerated display and the Luna software is just their version of screen sharing, like Apple's, or Microsoft's, or Zoom's, or whatever. That's my guess.

A real solution would have put more stuff in the dongle - the dongle would be responsible for compressing the signal and transmitting it too so the CPU wouldn't have to do any of the work. It would probably be much more expensive though.

 

[Amethyst1]

Probably a chip for the Luna Display EDID.

I noticed that when there's no session going on, it identifies as Luna Zero with a 1024×768 rez - when a session is running it's Luna Display with the respective rez of the session.