Force RGB Color on M1 Mac

Force-RGB-Color-on-M1-Mac.md

Force RGB Color on M1 Mac

How to Force RGB Color Output instead of YPbPr on your M1 Apple Silicon Mac for an External Monitor.

This step-by-step video tutorial will guide you through the procedure of forcing RGB color output on your M1 Mac.

Here is the direct link to the video tutorial: https://www.youtube.com/watch?v=Z1EqH3fd0V4

The video also has Closed Captions (Subtitles) that you can enable, to make it easier to follow if needed.

Please note that you're doing any changes on your own risk.

Terminal commands used in the video

Here are each of the Terminal commands mentioned in the tutorial, so that you can just copy and paste them:

open /Library/Preferences

plutil -convert xml1

plutil -convert binary1

plutil -lint

The step-by-step procedure on how to force RGB Color Output on M1 and M2 based Macs with Terminal commands

1. Open Terminal and use this command to make Finder select the displays plist file:
   open -R /Library/Preferences/com.apple.windowserver.displays.plist

2. Drag and drop the com.apple.windowserver.displays.plist file to Desktop manually. Don't use the cp command, as it won't add your current user with writing privileges.

3. Convert the file to XML:
   plutil -convert xml1 ~/Desktop/com.apple.windowserver.displays.plist

4. Open the converted file with the default plain text editor (avoid using the built-in TextEdit app if possible, since it might modify the file and make it unreadable by the system)
   open -t ~/Desktop/com.apple.windowserver.displays.plist
   or
   open -a CotEditor.app ~/Desktop/com.apple.windowserver.displays.plist

5. Copy and paste the missing LinkDesription Key under the current display (check the screenshot below for an example of how it should look like):
   

				<key>LinkDescription</key>
				<dict>
					<key>BitDepth</key>
					<integer>8</integer>
					<key>EOTF</key>
					<integer>0</integer>
					<key>PixelEncoding</key>
					<integer>0</integer>
					<key>Range</key>
					<integer>1</integer>
				</dict>

6. Save the file and then convert it to binary again:
   plutil -convert binary1 ~/Desktop/com.apple.windowserver.displays.plist

7. Check if the plist file is valid:
   plutil -lint ~/Desktop/com.apple.windowserver.displays.plist

8. Open the /Library/Preferences/ folder again:
   open /Library/Preferences/

9. Drag and drop the updated com.apple.windowserver.displays.plist file from Desktop to the Library folder manually. Don't use the cp command, as it won't add your current user with writing privileges.

10. Right Click on the com.apple.windowserver.displays.plist file in the Library folder and click on Get Info

11. Check the boxes for Stationery and Locked.

12. Reboot the Mac.

That's it!

(Alternative) Terminal commands to force RGB Color Output on M1 and M2 based Macs and workaround for losing RGB color after waking up from sleep

1. Open Terminal

2. Paste the following commands to edit the User's displays plist file com.apple.windowserver.displays.[UUID].plist using the built-in PlistBuddy function in macOS:

/usr/libexec/PlistBuddy -c "add DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:BitDepth integer" ~/Library/Preferences/ByHost/com.apple.windowserver.displays.*.plist
/usr/libexec/PlistBuddy -c "set DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:BitDepth 8" ~/Library/Preferences/ByHost/com.apple.windowserver.displays.*.plist
/usr/libexec/PlistBuddy -c "add DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:EOTF integer" ~/Library/Preferences/ByHost/com.apple.windowserver.displays.*.plist
/usr/libexec/PlistBuddy -c "add DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:PixelEncoding integer" ~/Library/Preferences/ByHost/com.apple.windowserver.displays.*.plist
/usr/libexec/PlistBuddy -c "add DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:Range integer" ~/Library/Preferences/ByHost/com.apple.windowserver.displays.*.plist

3. Reboot your Mac
   
   

(Workaround) If your Mac loses RGB color after waking up from sleep mode, either Reboot your Mac (recommended) or use this Terminal command to stop the WindowServer and login again (not recommended):

sudo killall -HUP WindowServer

End result

The end result is having your M1 mac output RGB color to your external monitor instead of YPbPr, potentially making the colors more accurate and the text a bit more crisp, even on older 1080p monitors.

Hopefully this tutorial would be useful to someone.

Please feel free to ask in the comment section if you have any questions regarding this procedure.

Background

While doing a lot of testing on how the Dual-Cable workaround makes RGB to work on M1, I've discovered what changes it makes to macOS, and managed to create a more streamlined workaround without the need to use a second cable.

To make things easier, I've created a step-by-step video tutorial of the whole procedure that should force RGB color output on your M1 Mac connected to an external monitor, and works on an HDMI-to-HDMI cable connection.

Credits

Big thanks goes to the amazing community and all their help over the years to solve issues like this:
https://gist.github.com/ejdyksen/8302862
https://gist.github.com/adaugherity/7435890

Useful Sources

Apple Open Source Project Files for Displays and Graphics
https://opensource.apple.com/source/IOKitUser/IOKitUser-1445.60.1/graphics.subproj/IODisplayLib.c
https://opensource.apple.com/source/IOGraphics/IOGraphics-517.17/IOGraphicsFamily/IOFramebuffer.cpp.auto.html

How to Edit and Convert binary plist files
http://hints.macworld.com/article.php?story=20050803111126899
https://apple.stackexchange.com/questions/155393/how-to-beautify-binary-dict-files
https://discussions.apple.com/thread/1768480

How to Edit plist files using defaults and PlistBuddy
https://ss64.com/osx/defaults.html
https://github.com/mathiasbynens/dotfiles/blob/master/.macos

Apps based on this method

@sudowork has created an awesome script written in Phyton that automates the steps and checks for duplicate files.
You can find more info about it here: https://github.com/sudowork/fix_m1_rgb

@dangh has created an alernative script for fishshell.
You can find more info about it here: https://github.com/dangh/force-rgb.fish

@GetVladimir I've also created a Shortcut to Force RGB Color Output using the built-in Shortcuts app.
You can find how to create the Shortcut here: https://gist.github.com/GetVladimir/c89a26df1806001543bef4c8d90cc2f8?permalink_comment_id=4531552#gistcomment-4531552

@entropyconquers has created a script based on this method written in Phyton that automates the steps, makes a backup and checks for duplicate files.
You can find more info about it here: https://github.com/entropyconquers/Force-RGB-Color-on-M1-M2-Mac-Script

Additional notes

Multiple PixelEncoding and Range keys in the same plist file
Note that there might be multiple instances of the PixelEncoding and Range keys in the same file, one for each output of your monitor and for different AirPlay devices. You might need to update the integer on each one to get RGB color output on all displays.

Getting RGB color only before login
There might be multiple duplicate plist files with the same name in different locations.

Make sure that you only have the main modified file in:
/Library/Preferences

Then make a backup and remove duplicate displays plist files from these locations (if any):
~/Library/Preferences
or
/Users/username/Library/Preferences
and
/Users/username/Library/Preferences/ByHost

Please note that you'll need to have administrator privileges in order to modify the file in /Library/Preferences. Thanks goes to @keegandent and @StrategicalIT for pointing this out.

Updates regarding macOS Monterey

USB-C to DisplayPort
From what I've seen, it seems that macOS Monterey 12.0.1 finally outputs RGB color by default on some monitors when using USB-C to DisplayPort cable on M1 Apple Silicone Macs.

You might need to make a backup and delete these 2 files:
/Library/Preferences/com.apple.windowserver.displays.plist
and
/Users/yourname/Library/Preferences/ByHost/com.apple.windowserver.displays.[UDID].plist

Restart your Mac and it should properly output RGB color on the monitor on the next boot.

HDMI to HDMI
The situation with HDMI seems to got a bit more complicated. Now the whole section for the LinkDescription might be missing from the com.apple.windowserver.displays.plist on a clean install and doesn't seem to be recreated when rotating the screen either.

Luckily, the solution still works, but you might need to manually add this whole section in the displays plist file:

					<key>LinkDescription</key>
					<dict>
						<key>BitDepth</key>
						<integer>8</integer>
						<key>EOTF</key>
						<integer>0</integer>
						<key>PixelEncoding</key>
						<integer>0</integer>
						<key>Range</key>
						<integer>1</integer>
					</dict>

The section usually goes right under the CurrentInfo key, and it should look something like this:

This should get your RGB color output working on M1 Mac mini, even when connected with HDMI to HDMI cable.

Multiple monitors when one them is using HDMI to HDMI
Additional thanks goes to @somogyi-ede who tested this with multiple monitors and confirmed that the LinkDescription key needs to be added under each monitor instance in order for all of them to receive RGB color output. Link to the comment

Updates regarding macOS 13 Ventura

USB-C to DisplayPort
The macOS 13 Ventura beta seems to outputs RGB color by default on some monitors when using USB-C to DisplayPort cable on M1 Apple Silicone Macs.

You might need to make a backup and delete these 2 files:
/Library/Preferences/com.apple.windowserver.displays.plist
and
/Users/yourname/Library/Preferences/ByHost/com.apple.windowserver.displays.[UDID].plist

Restart your Mac and it should properly output RGB color on the monitor on the next boot.

HDMI to HDMI
Similar as macOS Monterey, the situation with HDMI on macOS Venturs seems a bit more complicated. Usually the whole section for the LinkDescription might be missing from the com.apple.windowserver.displays.plist on a clean install and doesn't seem to be recreated when rotating the screen either.

Luckily, the solution still works, and you still need to manually add this whole section in the displays plist file:

					<key>LinkDescription</key>
					<dict>
						<key>BitDepth</key>
						<integer>8</integer>
						<key>EOTF</key>
						<integer>0</integer>
						<key>PixelEncoding</key>
						<integer>0</integer>
						<key>Range</key>
						<integer>1</integer>
					</dict>

The section usually goes right under the CurrentInfo key, and it should look something like this:

This should get your RGB color output working on M1 Mac mini, even when connected with HDMI to HDMI cable.

(Optional) Lock the plist file and set it as stationary
After the macOS Ventura 13.3 update, the plist file seems to get overwritten on reboot.

After you make the edits in the file, you can try setting the file /Library/Preferences/com.apple.windowserver.displays.plist as Stationery pad and Locked, so that it doesn't get overwritten on every reboot

To do this, right click on the plist file, click on Get Info and check the boxes next to Stationery pad and Locked

This requires further testing and might cause some issues, like not being able to remember new resolutions or display settings. Please note that you're making any changes at your own risk.

Updates regarding macOS 14 Sonoma Beta

USB-C to DisplayPort
The macOS 14 Sonoma seems to outputs RGB color by default when using USB-C to DisplayPort cable.

HDMI to HDMI
The macOS 14 Sonoma seems to outputs YCbCr color by default when using HDMI to HDMI cable.

• Forcing RGB Color Output still seems to work with the original procedure of modifying the plist files

• Modifying the display plist files still works with the alternative version

• After the plist files are modified, putting the Mac to sleep and waking it, it seem to keep the RGB Color output (this seems to be fixed at least on a M1 Mac mini)

If you have any additional questions, please feel free to contact me.

The menu on the LG UltraGear 27GL83A doesn't show the color format, but you can find it in the service menu by doing the following:

1. Turn off the monitor by pressing in the control stick on the bottom
2. Press the control stick left 3 times and right once
3. Turn the monitor back on by pressing in the control stick
4. Open the menu by pressing in the control stick and then pressing it right. This should open the service menu instead of the normal menu
5. Scroll to "DEBUG INFO." using the control stick (pressing it upwards 3 times should loop round to the debug info) and press it right to enter the debug info menu
6. Note the "COLOR FORMAT" displayed

You can exit the debug menu by pressing the control stick left, then exit the service menu by scrolling off the bottom of the menu using the control stick (pressing it downwards twice should do it) and pressing the stick in. Be sure not to accidentally change any values in the service menu!

These steps should hopefully work for other LG monitor models too.

@jackwilsdon that is awesome info! Thank you so much for sharing the detailed steps

@GetVladimir thank you for your work. I couldn't understand why apple put us through this! but thank you and the kind people out their providing this solution. BTW i struggle a bit, until i read about the byHost folder. I delete all the com.apple.windowserver.* files and now my mac m1 behaves.

@ioctlsg Thank you so much for your comment and I'm glad to hear that you got RGB color output working

Anyway, waiting for the fall release of the new OS where this nonsense has been fixed..

Wait, they fixed it? Do you have a source talking about this?

Anyway, waiting for the fall release of the new OS where this nonsense has been fixed..

Wait, they fixed it? Do you have a source talking about this?

@vittau under Sonoma you still have to do the configuration manually, but the wake from sleep and unplugging the external monitor and plugging back in works as expected now as the external monitor retains RGB signal

Here's the steps for Sonoma. Do exactly what it says here, or you will end up with a partially working setup. To my findings all the rebooting is necessary to also capture the login screen configuration.

1. Unplug external display, use only your laptop display for now
2. We want to start with a clean configuration, so delete the two com.apple.windowserver.* plists under /Library/Preferences and ~/Library/Preferences/ByHost
3. Reboot
4. Now we want macOS to set up all configurations that will naturally occur when using our setup. Open System Preferences and set your desired resolution scale
5. Reboot
6. Keep your laptop display open and plug in the external display. Open System Preferences and set your desired resolution scale and assign the desired main display where your dock and main windows will appear
7. Reboot
8. Close your laptop display so only the external display is being used. Open System Preferences and set your desired resolution scale
9. Reboot. Then, reboot again
10. Now we have all possible configuration variants set up in both plists. Copy the two com.apple.windowserver.* plists under /Library/Preferences and ~/Library/Preferences/ByHost to your Desktop manually (cp command will not transfer the needed user privileges)
11. Convert both plists on your Desktop to xml format with plutil -convert xml1 ~/Desktop/com.apple.windowserver.*
12. Open both plists in a text editor. We now want to find occurrences of only the external display and add some additional config lines to them. I'm not sure how to identify them properly, but my external display is 60Hz so that's what i used to differentiate from the 120Hz built-in display configs. Add the code at the bottom of this reply to each external display config in both plists. Consult the screenshot provided in the original gist at the top to where exactly it should be placed
13. Save both plists and convert them back to binary with plutil -convert binary1 ~/Desktop/com.apple.windowserver.*
14. Check if the plists are valid with plutil -lint ~/Desktop/com.apple.windowserver.*
15. Manually copy the updated plists back to their respective folders
16. Right click and Get Info on both, and set them to Stationary pad and Locked
17. Reboot and enjoy

<dict>
<key>BitDepth</key>
<integer>8</integer>
<key>EOTF</key>
<integer>0</integer>
<key>PixelEncoding</key>
<integer>0</integer>
<key>Range</key>
<integer>1</integer>
</dict>

@loucyan thank you so much for the detailed steps and explanation

So when Sonoma was released and theoretically Big Sur won't be getting any more updates I finally upgraded to Monterey 12.7 (I always stay a couple versions back for sanity on my main work machine). I had this RGB mode working under Big Sur but Monterey broke it and I can't seem to get it back.

My main monitor is a 27" Dell S2721QS 4K monitor, connected HDMI-to-HDMI directly to my M1 Mac Mini. My second screen is a 27" LG 27LQ635S-PU FHD TV, connected HDMI-to-HDMI through a USB-C Dock. I'm using a Display Override with "DisplayIsTV" set to false to prevent macOS seeing the HDTV as a TV, so I can set it to 1920x1080 instead of 1080p, which vastly improved text legibility on it, but I have no idea if that monitor is actually in RGB color mode or not, I'm assuming it is because it's not blurry anymore, but text quality did slightly degrade after moving to Monterey.

I had my /Library/Preferences/com.apple.windowserver.displays.plist locked when I upgraded and it was still there and locked after Monterey installed, but doesn't seem to actually be doing anything anymore. I've tried deleting the one "windowserver" file I had in ~/Library/Preferences/ByHost/com.apple.windowserver.displays.[UUID].plist and it respawned but still no RGB mode on my Dell monitor. I also tried adding another file to my Displays Overrides for the Dell also with "DisplayIsTV" set to false, but that didn't work either.

As a side note, Monterey also can't seem to remember my monitor arrangement. I have to reorder them every time I reboot.

At this point, the only reason I care about trying to get the Dell back into RGB mode is because it now randomly experiences the flickering and ghosting problem, which I never saw under Big Sur so long as it was in RGB mode.

In addition to two HDMI 2.0 ports the Dell monitor does have a DisplayPort 1.2 on it too, but I don't have any cables, adapters, or docks for it. I haven't seen anyone talking about using an HDMI-to-DisplayPort cable or adapter, or what color mode that defaults to, but I'm assuming it would have to be an active adapter. Unless a USB-C dock with DisplayPort would be a better option, and then plug my LG HDTV into the Mac's HDMI out? I'd really hate to have to buy new hardware to work around what is clearly a software problem.

@kmhcreative thank you for your comment and for the details.

You might want to try modifying the displays plist file in the ByHost too, as it will take precedence over the one in the Library.

Regarding the monitor arrangements, this was issue in Monterey and I'm not sure if it got resolved.

The workaround is to try a different HDMI port on the monitor and see if that helps

I tried using the "alternative" terminal commands shown above to modify the ByHost plist file and on reboot the Dell monitor is still in YPbPr color mode. I'll try the second HDMI port and see if that at least fixes the arrangement problem.

@kmhcreative thank you for the reply. You will have to modify two UUIDs in the plist file, since you have 2 monitors connected. Each one is only applied for one monitor.

Ok, if I’m understanding you correctly, you’re saying I should have TWO plist UUID files in my ByHost folder, one for each monitor? But I’ve only ever had one UUID plist file in my ByHost folder. If I delete it macOS only recreates one file. I have no idea if this matters, but in the “Mission Control” settings I have “Displays have separate spaces” checked — but I’d think if anything that would make it more likely to create two display files, since it’s not seeing both screens as one space.

And inside that plist file there are ELEVEN sub-arrays under key “Configs” each of which has two main sub-sections, seemingly referring to two separate monitors, one of which has an “OriginX” of “-1920.”

I have this old Ruby script that seems to still pull EDID UUIDs for each monitor. But NONE of the UUID strings in my plist files match the EDID UUIDs that Ruby script pulls. The UUID on the plist filename doesn’t match either of them either.

When I manually rearrange the monitors to their actual positions, instead of updating any of the existing configs, it simply inserts another new array with two sub-sections with UUIDs that don’t match anything else. So now there are an even DOZEN entries in that file.

I should note that only the last three of the Config arrays have “LinkDescription” sections until I run those “alternative” terminal commands. Which, by the way, shouldn’t there be another line on the end that reads:

/usr/libexec/PlistBuddy -c "set DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:Range 1" ~/Library/Preferences/ByHost/com.apple.windowserver.displays.*.plist

Otherwise it sets the Range to 0.

But the terminal commands only add the “LinkDescription” stuff to the first entry under “Config” and as soon as I manually re-arrange my monitors it overwrites it and the “LinkDescription” is gone. Not that it actually did anything in the first place.

Why does my Mac only create only one UUID display file in ByHost? And why does it have nearly a dozen entries, most of which don’t have a “LinkDescription” sub-section? Why does rearranging the monitors just add new entries to the file instead of changing configurations that are already there? Why do NONE of the UUID strings in that file seem to match the EDID UUIDs the Ruby script pulls?

On the other issue, switching HDMI ports on the monitor didn’t fix the arrangement problem. Switching which monitor is plugged into the Mac Mini HDMI and which is connected to the USB-C Dock, does fix the arrangement problem, but it always considers the HD screen the “Main” display, and even if I switch it in settings on the next boot it reverts back. It will ALWAYS set the Mac Mini’s HDMI port to “Main” and it will always position it to the left of the other display.

No changes in System Preferences will persist after a reboot.

I’m about ready to just give up on this. Thanks for your help though.

@kmhcreative you're welcome, glad if it helps.

There is only one displays plist file in ByHost folder.

Inside that file, there should be multiple UUID displays. You can add the LinkDescription to each one manually if you want to be sure.

Please note that you can't use the other scripts as they are only for x86 based Macs and they won't match the Apple Silicon UUIDs.

That being said, if you don't want to bother with this, the easiest workaround is to just connect both monitors with an USB-C to DisplayPort cable directly, without using a dock.

It will take up 2 USB-C ports on your Mac, but the displays should work properly and output RGB color

Fixed it!

Remember how I said that my locked /Library/Preferences/com.apple.windowserver.displays.plist file from Big Sur was untouched after my upgrade to Monterey? That was the problem. I had to trash that file and force macOS to generate a new one. But the XML <dict> literally just had UUID entries in it, nothing else. It wasn't until I went into System Preferences and rearranged my monitors correctly that it updated that plist file with actual configurations for both my monitors. Minus the "LinkDescription" sections, of course.

Then I went through the steps outlined above to add the "LinkDescription" section to each monitor's entry, rebooted, and my display arrangement is correct and my monitors are in RGB mode.

I stupidly assumed that the plist file from Big Sur would just work with Monterey, so the one thing I hadn't tried was getting rid of it and making Monterey generate a new one to edit, and I didn't think I needed to edit the Big Sur plist because it already had the "LinkDescription" sections in it. But Monterey clearly didn't like something in that file, and because it was locked it couldn't update it.

Lesson learned, now I know what I need to do when I eventually upgrade to Ventura so I won't lose my RGB mode again.

@kmhcreative awesome! Thank you for the update and the solution, and I'm glad to hear that you got RGB color output working

@GetVladimir many thanks for the great work that you have put in! I wanted to add a few things.

Alternate terminal way
This is a very nice and quick way to update plists, however, the values should be populated and Range is very important. This is the only way it works on my MacBook M2 Pro with LG C2. Also, if you have a true 10bit display, use BitDepth 10.
/usr/libexec/PlistBuddy -c "add DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:BitDepth integer" ~/Library/Preferences/ByHost/com.apple.windowserver.displays..plist
/usr/libexec/PlistBuddy -c "set DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:BitDepth 10” ~/Library/Preferences/ByHost/com.apple.windowserver.displays..plist
/usr/libexec/PlistBuddy -c "add DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:EOTF integer" ~/Library/Preferences/ByHost/com.apple.windowserver.displays..plist
/usr/libexec/PlistBuddy -c "set DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:EOTF 0” ~/Library/Preferences/ByHost/com.apple.windowserver.displays..plist
/usr/libexec/PlistBuddy -c "add DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:PixelEncoding integer" ~/Library/Preferences/ByHost/com.apple.windowserver.displays..plist
/usr/libexec/PlistBuddy -c "set DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:PixelEncoding 0” ~/Library/Preferences/ByHost/com.apple.windowserver.displays..plist
/usr/libexec/PlistBuddy -c "add DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:Range integer" ~/Library/Preferences/ByHost/com.apple.windowserver.displays..plist
/usr/libexec/PlistBuddy -c "set DisplaySets:Configs:DisplayConfig:DisplayConfig:DisplayConfig:LinkDescription:Range 1” ~/Library/Preferences/ByHost/com.apple.windowserver.displays..plist

Regarding YCbCr444 vs RGB
If you have a Mac with HDMI 2.1 (starting with M2 Pro) and are able to get 10bit YCbCr444 (check screen OSD information, if on LG C2, keep clicking green button on the remote) working by default, I do not recommend messing around. 4:4:4 means no chroma subsampling and you will get absolutely no visual benefits from trying to get RGB to work. In theory, RGB has a slightly wider range, but as long as both your screen and computer are working on the same range (i.e. limited or low black level), it will sort itself out so that no one ever will be able to see any difference (especially at 10bit). Rather focus on getting a good calibration and your creative work.

@Eclipt1c Thank you so much for your comment and for the additional info for 10 bit color.

Regarding the YCbCr444 vs RGB, it seems there is a difference in the default color profile that macOS chooses, which could affect colors and calibration

When connecting to HDMI on my m1 MacBook Air, RGB output was successful, but the gamma value was destroyed (presumed to be an HDMI bandwidth issue).
When connected via DP, ypbpr is still output (in this case, the gamma value is normal).

@mnsk0000 if you're using a Dell monitor, make sure to set the Gamma to PC instead of Mac in the Monitor built-in menu and see if it makes a difference

@GetVladimir I using a Dell monitor, But this model not support Gamma setting menu

@mnsk0000 In that case, you can try changing the gamma in the color profile. Here is how to calibrate it in macOS Sonoma: https://support.apple.com/en-ie/guide/mac-help/mchlp1109/mac

@GetVladimir I can't setting gamma to Display Calibrator Assistant. I was only able to change the color temperature through this.

When connecting to HDMI on my m1 MacBook Air, RGB output was successful, but the gamma value was destroyed (presumed to be an HDMI bandwidth issue). When connected via DP, ypbpr is still output (in this case, the gamma value is normal).

When I connected both hdmi and dp and output to dp, I succeeded in outputting RGB from dp.
However, the gamma value still appears to be destroyed, so it may not be an HDMI issue.

@mnsk0000 Make sure to hold the ALT/OPTION button on your keyboard while clicking on the + on the color profile.

It should appear a checkbox with Expert Mode and the Gamma should be available:

@GetVladimir Thanks you
Have you or anyone else had any gamma issues?
monitor.co.kr The third on this site list is the contrast ratio test.
I couldn't distinguish values ​​above 92 in this test (I could distinguish them in ycbcr state)

@mnsk0000 Thank you for the info. I personally haven't noticed issues with Gamma unless the setting on the Monitor itself is set to the wrong value.

The slider that you've posted might be affected by contrast and brightness also though, as well as high RGB and low RGB (limited RGB and full RGB) range values

@GetVladimir When I connected it with DP
I found that it works as RGB at 30hz and ypbpr at 60hz.

@mnsk0000 that doesn't sound right. Are you sure the USB-C to DisplayPort cable that you use is good for 4K60? (Many usually are)

@GetVladimir The cable is fine. I Connected to DP-DP via Hub.
This could be a case of my hub or monitor being unusual.

@mnsk0000 thank you for the reply and for the info.

You're right, in that case the issue is very likely the hub not supporting 4K60 output.

Connecting your M1 MacBook Air with a direct USB-C to DisplayPort cable to the Dell monitor should solve the issue