How to force RGB in Mac OS X

README.md

How to force RGB in Mac OS X

• Download the patch-edid.rb script from the forums thread above and put it in your home directory.
• Connect only the external monitor(s) in question (I closed my MacBook lid, for example). The script will make override files for any connected monitor.
• Type “ruby patch-edid.rb” in Terminal.
• A new folder will be created in your home directory. Move it into the “/System/Library/Displays/Contents/Resources/Overrides” folder. If Finder tells you that you are overwriting an existing folder, consider backing it up first.
• Restart your computer, enjoy your monitor.

DisplayVendorID-1e6d.DisplayProductID-59f2

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>DisplayProductName</key>
  <string>Display with forced RGB mode (EDID override)</string>
  <key>IODisplayEDID</key>
  <data>AP///////wAebfJZAQEBAQEXAQSlQxx4hsqVplVOoSYPUFSlS4BxT4GAgcCp
wLMAAQEBAQEBfkgA4KA4H0BAQDoApSIhAAAYAjqAGHE4LUBYLEUApSIhAAAa
AAAA/ABMRyBVTFRSQVdJREUKAAAA/QA4Sx5aGAAKICAgICAgAMc=
</data>
  <key>DisplayVendorID</key>
  <integer>7789</integer>
  <key>DisplayProductID</key>
  <integer>23026</integer>
</dict>
</plist>

How to modify System Integrity Protection in El Capitan.md

Follow these steps to disable SIP:

• Restart your Mac.
• Before OS X starts up, hold down Command-R and keep it held down until you see an Apple icon and a progress bar. Release. This boots you into Recovery.
• From the Utilities menu, select Terminal.
• At the prompt type exactly the following and then press Return: csrutil disable
• Terminal should display a message that SIP was disabled.
• From the  menu, select Restart.

You can re-enable SIP by following the above steps, but using csrutil enable instead.

patch-edid.rb

#!/usr/bin/ruby
# Create display override file to force Mac OS X to use RGB mode for Display
# see http://embdev.net/topic/284710
# 
# Update 2013-06-24: added -w0 option to prevent truncated lines

require 'base64'

data=`ioreg -l -w0 -d0 -r -c AppleDisplay`

edid_hex=data.match(/IODisplayEDID.*?<([a-z0-9]+)>/i)[1]
vendorid=data.match(/DisplayVendorID.*?([0-9]+)/i)[1].to_i
productid=data.match(/DisplayProductID.*?([0-9]+)/i)[1].to_i

puts "found display: vendorid #{vendorid}, productid #{productid}, EDID:\n#{edid_hex}"

bytes=edid_hex.scan(/../).map{|x|Integer("0x#{x}")}.flatten

puts "Setting color support to RGB 4:4:4 only"
bytes[24] &= ~(0b11000)

puts "Number of extension blocks: #{bytes[126]}"
puts "removing extension block"
bytes = bytes[0..127]
bytes[126] = 0

bytes[127] = (0x100-(bytes[0..126].reduce(:+) % 256)) % 256
puts 
puts "Recalculated checksum: 0x%x" % bytes[127]
puts "new EDID:\n#{bytes.map{|b|"%02X"%b}.join}"

Dir.mkdir("DisplayVendorID-%x" % vendorid) rescue nil
f = File.open("DisplayVendorID-%x/DisplayProductID-%x" % [vendorid, productid], 'w')
f.write '<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">'
f.write "
<dict>
  <key>DisplayProductName</key>
  <string>Display with forced RGB mode (EDID override)</string>
  <key>IODisplayEDID</key>
  <data>#{Base64.encode64(bytes.pack('C*'))}</data>
  <key>DisplayVendorID</key>
  <integer>#{vendorid}</integer>
  <key>DisplayProductID</key>
  <integer>#{productid}</integer>
</dict>
</plist>"
f.close

Excellent! It worked on Sequoia. I had to install the RX570 VBIOS on my RX580 video card for the Hackintosh to work with graphics acceleration. The HDMI output was fine. However, when I needed the Dual DVI output for the second monitor, the image had pink and green colors, horrible. I used your method and it solved my problem. Remember that currently the folder to put the generated file is in "/Library/Displays/Contents/Resources/Overrides"
Currently the System folder is protected and does not accept modification.
You saved me! Thank you!