I have been able to fix the external display issues via HDMI and DisplayPort I was having with my 2018 MBP running MacOS High Sierra 10.13.6. If your external display is showing color fringing around the text, especially within the Operating System menus or seems to be showing a drastically reduced quality signal than what it should, forcing your computer to use RGB mode for the external display might be the fix.
Using the script Andrew Daugherity created I’ve updated the instructions to try and be as thorough and user-friendly as possible so you can easily follow along and perform this fix with a single computer.
1. Download the script by Andrew Daugherity:
https://gist.github.com/adaugherity/7435890
2. Create a folder on your desktop titled “Display Fix”
3. Drag the script file “patch-edid.rb” from the folder in your downloads titled with a ton of numbers and letters into this folder on your desktop.
4. Connect your laptop up to the display you are going to be using. Preferably with the laptop closed running only the external display.
5. Open the app “Terminal”
6. Drag the file “patch-edid.rb” into the Terminal window. A file path will appear. Hit Enter. This should complete in a few seconds.
7. Go to your Finder App Menu (the navigation bar on the top of the desktop) Select Go>Home. There will be a folder titled “DisplayVendorID-XXX”. Mine is titled DisplayVendorID-469, Yours will be different and is specific to your display.
8. Drag “DisplayVendorID-XXX” into the Display Fix folder on your desktop.
9. Create a new folder in the Display Fix folder titled “Old Display Pref”
10. Disconnect your laptop from your external display and shut it down.
11. The file you need to alter is a system file that is protected by Apple to reduce malware or also you accidentally messing up something critical to the operating system. You need to temporarily disable this protection. Press the power button to start your laptop up and immediately hold Command + R. As soon as you see the loading bar you can release the keys. This will start your laptop in recovery mode.
12. Select your language.
13. Go to the Application Menu > select Utilities > click on and open Terminal
14. Type, no quotation marks, in the command “csrutil disable” and hit enter. It will tell you the computer must be restarted for the changes to take place.
15. Go to the Apple Menu (top bar, Apple logo) and select restart.
16. Once your computer has restarted go to the Finder App Menu, Select Go > Computer > Macintosh HD > System > Library > Displays > Contents > Resources > Overrides.
17. In Overrides look for the folder name that matches the folder name that the script created and you placed into the Desktop Fix folder. For example, if the folder that was created is “DisplayVendorID-ABC” then look for that corresponding file in the Overrides folder.
18. Open your Display Fix folder on your desktop and drag the folder (example: DisplayVendorID-ABC) from Overrides into the Old Display Prefs folder. This is to save your original in case you want to go revert back for any reason. I zipped this Old Display Prefs folder (right click > compress) and stored it on my iCloud in a folder of things I keep for “just in case” backup reasons.
19. Now that you’ve backed it up, delete this folder from the Overrides folder.
20. Next drag the new folder that was created by the script from your Display Fix folder into the Overrides folder.
21. Shut down your computer.
22. Press the power button and immediately hold Command+R, you can let go of the keys when a loading bar appears.
23. Go to the Application Menu > select Utilities > Click and open Terminal
24. Type, no quotation marks, the command “csrutil enable” then hit enter. It will say the computer needs to restart for the changes to take effect.
25. Go to the Apple Menu (top bar, Apple logo) and select restart.
26. Once your computer has restarted open the terminal app and type, no quotes, “csrutil status”. If it says it is still disabled please repeat steps 21-24 to enable this properly to protect the integrity of your operating system. If it says enabled continue.
27. Connect your External Display. The issue should be fixed. If not see #29.
28. Since you have backed up your Old Display Prefs folder somewhere you can now trash the Display Fix folder from your desktop.
29. Go to the Apple Menu (top bar) > System Preferences > Displays > Color. Under Display Profile you should see “EDID override”. If you do not see this you might not have placed the correct newly created folder from the script into the Overrides folder. Return to step 11. Or the script might not have correctly created the new folder, see step #4.
Hope this helps someone else out there!
