MacOS respects true color displays preventing dither + save monitor

simplex

I can make same with my 2nd 2420z which is also 6+FRC ( I mean, dissasambly )

Imagine if firmware edit is key ?

WhisperingWind

The firmware will be in binary format, so we'll need a decompiler to convert it into assembly. I'm afraid analyzing this code will be a very time‑consuming process and will require deep expertise in the subject area. If you have the necessary knowledge and time, you can give it a shot. From my side, though, I can't really say whether that would work.

jordan

I only have IPS and TN monitors.

AshX

That same trick works on my second monitor, the BenQ GL2450 (TN, 6bit+FRC). The Mac mini 2018 actually feels better when running in 10-bit mode with Reduce Motion turned on.

Still, to my eyes, the MacBook Pro M1 is slightly more comfortable to look at when connected to this monitor compared to the Mac mini 2018 — both are running Sonoma. What’s interesting is that the MacBook Pro M1 only outputs an 8‑bit signal — BetterDisplay doesn’t even give me a 10‑bit option to select.

As for whether Reduce Motion actually helps on the MacBook Pro M1 + BenQ GL2450 (TN, 6bit+FRC), I still can't say for sure. At first, I thought it did — but when I ran a blind test (on/off), it didn’t give clear results. I definitely need to do more testing.

I'll test this on a 6-bit + HighFRC IPS monitor later this week. And in a couple of weeks, I plan to try it out on my TV with its 8-bit+FRC IPS panel.

jordan

WhisperingWind If you had a eink monitor you can see how the dithering looks as the eink pixels are visible clearly when temporal dithering is active.

AshX

@aiaf and others saw the Apple dithering conflicting with a monitor’s FRC, especially on 6 bit+FRC displays. So that could be what you’re seeing.

It’s confirmed Stillcolor and BetterDisplay outputting 8-bit results in a clean output on Apple Silicon. What is occurring on your 2018 Mini running Sonoma is a whole other question. Unfortunately you can’t DFU downgrade Intel Macs firmware like you can with Apple Silicon using an IPSW, so even if you did a test downgrading to say, Mojave or Catalina, which pre-existed Apple Silicon, I don’t know how the newer firmware would interact.

It would be great to expand your testing to a true 8-bit or even an 8-bit+FRC to see what changes.

macsforme

AshX Unfortunately you can’t DFU downgrade Intel Macs firmware like you can with Apple Silicon using an IPSW, so even if you did a test downgrading to say, Mojave or Catalina, which pre-existed Apple Silicon, I don’t know how the newer firmware would interact.

To add some nuance, this is true for T1/T2 Macs, where BridgeOS can only be flashed with the version currently signed by Apple (usually only the latest version; similar to an iPhone or iPad). With older Intel Macs, it is technically possible to reconstruct an old firmware version and flash it with an EEPROM programmer and the right adapters. I have done this a few times for 2015 retina MacBook Pros, but at least for this model I believe I saw no difference in reported VBIOS versions for either the Intel iGPU or the AMD DGPU between the oldest available Apple firmware and the newest, neither did I find any subjective improvement in eye strain.

simplex

WhisperingWind

the scaler of bl2420z is rtd2486ard

Here is cuted datasheet, but some features are: 10-bit color processing, advanced dithering for 6-bit panels

DP1.2 support 6…12-bit color depth transport

https://285624.selcdn.ru/syms1/iblock/fa2/fa212868c97e86c5feb70d2820d6458d/RTD2486AD_confidential_spec.pdf

You can check your scaler holding Menu when power-on, then enter menu again

And double dithering inside Chip data path wow. Perhabs, thats why I dont feel less pixel motion when put 6-bit on this monitor, only colors truncated

AshX

WhisperingWind That same trick works on my second monitor, the BenQ GL2450 (TN, 6bit+FRC). The Mac mini 2018 actually feels better when running in 10-bit mode with Reduce Motion turned on.

Still, to my eyes, the MacBook Pro M1 is slightly more comfortable to look at when connected to this monitor compared to the Mac mini 2018 — both are running Sonoma. What’s interesting is that the MacBook Pro M1 only outputs an 8‑bit signal — BetterDisplay doesn’t even give me a 10‑bit option to select.

As for whether Reduce Motion actually helps on the MacBook Pro M1 + BenQ GL2450 (TN, 6bit+FRC), I still can't say for sure. At first, I thought it did — but when I ran a blind test (on/off), it didn’t give clear results. I definitely need to do more testing.

I'll test this on a 6-bit + HighFRC IPS monitor later this week. And in a couple of weeks, I plan to try it out on my TV with its 8-bit+FRC IPS panel.

What model M1 MBP are you using? The 13”, 14”, or 16”? Can you share the specifics of the build and what exact version of Sonoma you’re running? I know Big Sur and Monterey would switch between 8-bit and 10-bit framebuffers, but it seems to be purely 10-bit since Ventura. I ask about the particular device build and model because the M1 13” MBP and M1 13” MBA both use the older Retina panels supporting “millions of colors” and during the Intel era, had more limitations at least in their color output for external displays.

Please keep us posted on your testing! I feel like you may be able to uncover some interesting facts about the Apple Silicon display engine:

jordan

simplex Also EDID reveals the scalar on some monitors. So I wonder how we can edit the scalar settings?

WhisperingWind

simplex

The scaler of BenQ GL2450 is MST TSUMU58PWHL.

AshX

What model M1 MBP are you using?

MacBook Pro M1 13", macOS Sonoma 14.1.2 (23B92).

What’s interesting is that the MacBook Pro M1 only outputs an 8‑bit signal — BetterDisplay doesn’t even give me a 10‑bit option to select.

I know Big Sur and Monterey would switch between 8-bit and 10-bit framebuffers, but it seems to be purely 10-bit since Ventura.

My monitor is connected via DVI to both Macs (since the monitor is old and only has two inputs: DVI and VGA). However, the Mac mini is capable of outputting 10-bit (though there is a question: is it true 10-bit or 8-bit + spatial dithering), while the MacBook can only output 8-bit.

But if I use HDMI-HDMI cable to my TV instead of an HDMI/Type-C - DVI, then the MacBook will provide a choice between 8 and 10 bits.

I ask about the particular device build and model because the M1 13” MBP and M1 13” MBA both use the older Retina panels supporting “millions of colors” and during the Intel era, had more limitations at least in their color output for external displays.

For the built-in display, only 8-bit is available for selection. I believe my MacBook's display uses 8-bit+FRC.

simplex

and dithering settings via registers:

JTL

jordan Also EDID reveals the scalar on some monitors

Any examples?

jordan So I wonder how we can edit the scalar settings?

I think it's "hardcoded" in the firmware, but some monitors may allow reprogramming over an external interface (i.e, without disassembling the unit)

simplex

jordan we can edit the scalar

EDID is only 128 or 256 bytes data which transfer from scaler to user. Sometimes you can re-write it with service-menu option in some monitors. As JTL wrote, some scalers do accept re-flash via VGA cable (or similar) without opening

jordan

JTL well when i checked my boox mira pro it said RTK2155 or something which is accurate as I completely tore down my mira pro already and saw the chip on the board. I also checked another monitor in the past and it also had it in the edid, a similar rtk (realtek) chip.

I think a ch341a could maybe work to reprogram a monitor as long as theres the chip exposed that has the data on it. I have controlled a monitor with DDC commands in the past so maybe some monitor expose dithering parameters with DDC?

AshX

WhisperingWind

This is really interesting. I have a 13” M2 MBP that I downgraded to Monterey 12.4. This seems to prove that there in fact is a difference in the display engine of the older Retina Macs, and the Mini and newer Macs. I’m curious if my M2 would behave the same or if this is an inherent bottleneck on the M1 chips when used in a Retina Mac compared to Mac Minis and MiniLED MBPs of that era.

I forget who posted saying their 13” MBA M1 was comfortable on their external display and then they bought an M1 Mac Mini and it was uncomfortable even when running the identical OS and firmware as the MBA.

WhisperingWind

For the Mac mini 2018 paired with the BenQ BL2420PT monitor (IPS, 6-bit+FRC), I find the 10-bit output setting (versus 8-bit) produces the most visually comfortable image.

The separate Windows 10 22H2 PC (Intel UHD 730) only outputs 8-bit to this monitor, yet the image looks as comfortable as 10-bit on the Mac.

A Mystery: To the naked eye, it's puzzling why the Mac mini's video subsystem behaves this way compared to the Windows PC and my M1 MacBook Pro. When I have time, I plan to analyze the HDMI output with a recorder to get concrete data on what's happening.

AshX

I bought a MacBook Pro 16" M1 Max with a MiniLED display a year ago. It was extremely uncomfortable to use with my external BenQ GL2450 monitor. Although the MacBook Pro M1 was very comfortable with the same monitor. I sold the MacBook Pro 16" M1 Max.

The only thing that made it OK was the option to stream the content of the virtual display in BetterDisplay to the physical BenQ GL2450 display. But the performance in this case wasn't great.

I tried it on several operating systems, including Sonoma. When comparing it with the MacBook Pro M1, I always brought both MacBooks to the same OS and firmware version via DFU.

P.S. Additional Note on the BenQ BL2420PT: although this monitor is advertised as PWM-free, it has a different kind of signal spike that can also cause eye strain during long sessions.

WhisperingWind

I installed Sonoma, Sequoia, and Tahoe on my MacBook Pro M1. However, I returned to Sonoma without using DFU. I also don't see any noticeable difference in terms of eye strain when running Sonoma with the firmware from Sonoma, Sequoia, or Tahoe.

On my Mac mini 2018, I also use Sonoma after installing and removing Sequoia. I don't notice any difference related to the firmware in terms of eye strain either.

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