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.

thanks for reply! i just bought that cable and it works. my monitor doesn't not a have an over/underscan control, and it seems that the control has also been removed from Monterey. https://discussions.apple.com/thread/253364474
so, your suggestion is the best, and you helped me understand the situation rapidly as someone who has been away from display tech for over a decade.
i guess there MAY be a way to manually change the underscan value in a plist file, but you would have suggested it.

@bombjoke thanks for the reply! Awesome, glad to hear that you got it working properly.

The underscan slider in System Preferences only seemed to show on older versions if you have very specific resolutions selected (like 1080p) and the monitor is being detected as a TV. Getting it to show and work wasn't always reliable.

Either way, don't regret getting the USB-C cable, as it solved the issue and it might have solved other issues as well, now that it detects the monitor properly

@GetVladimir
Okay, now I upgraded to macOS Monterey. As I feared, my old monitor again shows the greenish and purple color. Unfortunately nothing helped. I copied the plist file and used the Python script again. But the one display doesn't show the correct colors anymore. I hope I can go somehow back to Big Sur.

@MarkusMangold thank you for the update.

You usually don't need to make any changes after the update. Just copy over your backup plist file and make sure there is no duplicate plist file in the ByHost folder

@GetVladimir Yes, that is what I've done (in the first place). I think I know what the problem is, it seems when booting the resolution is different than before. Anyway I could solve it, but this only works for me. Since my monitor has a DVI input I am now using a HDMI-to-DVI cable. I learned that DVI is RGB only. And what shall I say: it now works flawlessly without changing anything. 🙂
It was a bit of fiddling since there are three computers sharing the monitors but it works and I coudn't be happier. Let's hope Ventura does not change anything here.

@MarkusMangold You're right, DVI is RGB only, so that's a good solution.

Funny thing how an older technology saves the day and works better with the M1. Glad to hear that you got it working

I'm using an external HDMI DELL display on MacOS 12.6 Macbook Pro 16" M1 and editing the plist hasn't worked. From what I understand my plist is registering multiple formats of my display. I was able to identify which display is which by maintaining orintation to 90º. Even so, I was unable to get it working. Here's how my Plist is currently:

`

DisplayAnyUserSets Configs CurrentInfo Depth 8 High 1117 Hz 120 IsLink OriginX 0.0 OriginY 0.0 Rotation 0 Scale 2 Wide 1728 Rotation 0.0 UUID 37D8832A-2D66-02CA-B9F7-8F30A301B230 UnmirrorInfo Depth 4 High 1 Hz 60 IsLink OriginX 0.0 OriginY 0.0 Rotation 0 Scale 1 Wide 1 CurrentInfo Depth 8 High 1920 Hz 60 IsLink OriginX -1080 OriginY -1080 Rotation 0 Scale 1 Wide 1080 LinkDescription BitDepth 8 EOTF 0 PixelEncoding 0 Range 1 PixelEncoding 0.0 Range 1 Rotation 0.0 UUID 8BCACC85-9FA3-4E52-89E2-DB9743795D49 UnmirrorInfo Depth 4 High 1 Hz 60 IsLink OriginX 0.0 OriginY 0.0 Rotation 0 Scale 1 Wide 1 CurrentInfo Depth 8 High 1117 Hz 120 IsLink OriginX 0.0 OriginY 0.0 Rotation 0 Scale 2 Wide 1728 LinkDescription BitDepth 8 EOTF 0 PixelEncoding 0 Range 1 Rotation 0.0 UUID 37D8832A-2D66-02CA-B9F7-8F30A301B230 UnmirrorInfo Depth 4 High 1 Hz 60 IsLink OriginX 0.0 OriginY 0.0 Rotation 0 Scale 1 Wide 1 CurrentInfo Depth 8 High 720 Hz 60 IsLink OriginX 1728 OriginY 0.0 Rotation 0 Scale 1 Wide 1280 Rotation 0.0 UUID 7B3CCC39-7B95-4000-B05C-BD1BAF887A8B UnmirrorInfo Depth 4 High 1 Hz 60 IsLink OriginX 0.0 OriginY 0.0 Rotation 0 Scale 1 Wide 1 CurrentInfo Depth 8 High 1117 Hz 120 IsLink OriginX 0.0 OriginY 0.0 Rotation 0 Scale 2 Wide 1728 Rotation 0.0 UUID 37D8832A-2D66-02CA-B9F7-8F30A301B230 UnmirrorInfo Depth 8 High 1117 Hz 120 IsLink OriginX 0.0 OriginY 0.0 Rotation 0 Scale 2 Wide 1728 CurrentInfo Depth 4 High 921 Hz 60 IsLink OriginX 1728 OriginY 0.0 Rotation 0 Scale 1 Wide 1228 Rotation 0.0 UUID 377CA1AA-88C6-4855-ACFD-C2B9D4A43BBB UnmirrorInfo Depth 4 High 921 Hz 60 IsLink OriginX 0.0 OriginY 0.0 Rotation 0 Scale 1 Wide 1228 Orientations 377CA1AA-88C6-4855-ACFD-C2B9D4A43BBB 0 37D8832A-2D66-02CA-B9F7-8F30A301B230 0 7B3CCC39-7B95-4000-B05C-BD1BAF887A8B 0 8BCACC85-9FA3-4E52-89E2-DB9743795D49 90 Underscan 377CA1AA-88C6-4855-ACFD-C2B9D4A43BBB 1 37D8832A-2D66-02CA-B9F7-8F30A301B230 1 7B3CCC39-7B95-4000-B05C-BD1BAF887A8B 1 8BCACC85-9FA3-4E52-89E2-DB9743795D49 1 Version 1 DisplayUUIDMappings 25DD932C-22DE-4153-0F93-5A69417CA049 377CA1AA-88C6-4855-ACFD-C2B9D4A43BBB 9B603E2E-98E1-E840-0F93-5A69417CA049 E5C091A1-93C3-45B5-9AC4-B3826E516DF9 B42D5FF6-E50E-D8A2-0F93-5A69417CA049 7B3CCC39-7B95-4000-B05C-BD1BAF887A8B FA8FEBE2-00C2-6D27-0F93-5A69417CA049 8BCACC85-9FA3-4E52-89E2-DB9743795D49 `

@danielgbr thank you for the comment and the details.

Can you tell me more how is the connection to the Dell monitor? Is it using a direct USB-C to HDMI cable or goes through an adapter/dock?

If it's using a direct connection, please check if there is a duplicate plist file in /Users/yourname/Library/Preferences/ByHost/com.apple.windowserver.displays.[UDID].plist that needs to be edited or deleted (after making a backup)

@danielgbr thank you for the comment and the details.

Can you tell me more how is the connection to the Dell monitor? Is it using a direct USB-C to HDMI cable or goes through an adapter/dock?

If it's using a direct connection, please check if there is a duplicate plist file in /Users/yourname/Library/Preferences/ByHost/com.apple.windowserver.displays.[UDID].plist that needs to be edited or deleted (after making a backup)

Im using HDMI - HDMI and the /ByHost/ doesn't exist

@danielgbr that's very interesting, thank you for the reply. I would have expected the HDMI to HDMI connection not to cause such issues.

Please make a backup and delete the display plist file. Then reboot the Mac and it should recreate a new file. Apply the procedure on it again and RGB color output should work.

Let me know if it starts to show multiple UUIDs again on the newly created plist file.

I just deleted the plist file. When I restart it is showing multiple UUIDs again (a total of 5 UUIDs) after I rotate the extended external monitor. What should I do?

@danielgbr you can try to repeat the steps as you did before and change/add the PixelEncoding to the UUID of the external monitor.

Be careful and please know that you're doing any changes at your own risk.

I receive the following error after converting the file back to binary1. I'm using a MacBook Air M2. Copied and pasted the whole LinkDescription section

Using mac OS Ventura

@rodogd Thank you for your comment.

Please try to edit the plist file with another plain text editor and make sure there are no missing characters.

You can use the free and open source CotEditor that is available on the Mac App Store.

@GetVladimir Thanks for the quick response. It worked using CotEditor. However, when I changed the resolution to 4k, the issue came up again and I'm still not able to fix it. Will try switching back to 1080p and will let you know

Since macOS Ventura (final version) this doesn't work any more, unfortunately. Even when LinkDescription etc. is present for all displays in all relevant com.apple.windowserver.displays.plist files, it switches back to YPbPr as soon as the MacBook comes back from standby. Only after rebooting it goes back to RGB, but on first standby and wake it's back to YPbPr. This didn't happen in Monterey. Any ideas?

@rodogd Great, glad to hear that you got it working.

If you change the resolution, it overwrites the plist file. Set the resolution that you want to use and modify the plist file afterwards.

Once you get it working, make a backup of the working plist file so that you can easily restore it

@m1norgb thank you for your comment. Awesome username BTW :)

I've tested it on the public release on Ventura yesterday and the procedure still works. When the Mac goes to sleep and wakes, it seems to keep the RGB color output.

Can you check if there is a duplicate plist file in the ByHosts folder? Or are there more UUID entries that need to have the LinkDescription after waking from sleep?

@GetVladimir : There's no duplicate plist file in the ByHosts folder (I created one there manually, but that didn't help either, so I removed it again). The problem is the main /Library/Preferences/com.apple.windowserver.displays.plist file. Whenever the Macbook comes back from sleep, the LinkDescription section gets removed there and the monitor is back to YPbPr. That wasn't the case in Monterey.

I've now ordered a CalDigit Thunderbolt Dock and plan to connect the Macbook to the dock and the dock to the monitor via Displayport. Maybe this will finally solve the problem.

@m1norgb thank you for the update and for the details.

I'm not sure whether or not the dock will solve the issue. Let us know how it goes

@GetVladimir I'll report back on the dock. If it doesn't solve the problem I'm going to send it back.

I just hope that Apple will soon fix this bug. Apparently it's been reported to Apple already more than a year ago.

I also wonder whether the Apple Studio Display does have this issue as well?

I'm on Ventura. I've tried everything recommended here, deleting all possible duplicate plist files. I've also done a search that includes system files and found no other duplicates.

My Dell S3221QS monitor correctly displays in RGB mode at the MacOS login screen, but as soon as I log in it switches back to YPbPr. The /Library/Preferences/com.apple.windowserver.displays.plist file gets overwritten at login time.

EDIT: I got it working! The key was not to delete the ByHosts version of the file, but to modify it in the same way as the Library/Preferences file.

@gavingt Thank you so much for your comment and for the updated solution! I'm glad to hear that you got RGB color output working

@gavingt : Is it still in RGB mode when you put your Mac to sleep and wake it again? That's where it switches back to YPbPr for me.

@gavingt Yes, for me on M1 Mac mini it keeps it RGB after going to sleep and wake up.

However, other users have reported that on MacBook and on Ventura 13.0 it might revert back to YPbPr after waking up.

A real fix need to be added in future Ventura updates.

A suggested workaround was either to prevent the Mac from going to sleep when the display goes to sleep, or to lock only the displays plist file in ByHost from editing, but I haven't tested this myself and I can't recommend it.

Locking it might cause issues, so please note that you'll be doing any changes fully at your own risk.

@m1norgb Unfortunately, it did revert to YPbPr upon waking from sleep.

Hey @GetVladimir, I'm thinking about purchasing this monitor. Could you tell me if I would have any problem getting it to work on macOS Ventura?

@xilopaint thank you for your question.

From what I could find from the LC49RG90SSLXZD model number, it seems to be an Ultrawide 1440p resolution 144Hz monitor.

While this resolution might be great for gaming, it's very likely for macOS to have scaling, font clarity and refresh issues with it.

However, this is just based on the technical specifications I could find. I haven't used or tested this monitor myself, so I can't really tell how well it will work

@GetVladimir thanks for your fast reply! As you understand I would need this "Force RGB" hack to make it working on macOS Ventura and the new MacBook Pro M2?

@xilopaint you're very welcome, glad if it helps.

Yes, you will need that if you use HDMI-to-HDMI connection or a dock/adapter.

If you use an USB-C to DisplayPort cable, you might not need to make any modifications