1-Force RGB mode for OS X.md

This Gist contains the script and generated output file for an Acer B276HUL.

The pre-generated file below is known to work with:

• OS X Mavericks
• OS X Yosemite
• OS X El Capitan

For El Capitan:

1. Restart your Mac while holding Command-R: this puts your Mac into Recovery Mode.

2. When in Recovery Mode, select Utilities > Terminal from the menu bar.

3. In the Terminal type csrutil disable: this disables System Integrity Protection

4. Restart your Mac and log in.

5. Issue the following instructions:

   sudo mkdir /System/Library/Displays/Contents/Resources/Overrides/DisplayVendorID-472
   sudo cp DisplayProductID-361 /System/Library/Displays/Contents/Resources/Overrides/DisplayVendorID-472

6. Restart your Mac while holding Command-R for Recovery Mode

7. When in Recovery Mode, select Utilities > Terminal from the menu bar.

8. In the Terminal type csrutil enable: this reenables System Integrity Protection

9. Restart your Mac

For Yosemite and Mavericks:

1. Issue the following instructions:

   sudo mkdir /System/Library/Displays/Overrides/DisplayVendorID-472
   sudo cp DisplayProductID-361 /System/Library/Displays/Overrides/DisplayVendorID-472

DisplayProductID-361

<?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>Acer B276HUL - forced RGB mode (EDID override)</string>
  <key>IODisplayEDID</key>
  <data>AP///////wAEcmEDs0xgMhoXAQS1PCJ4Ikt1p1ZLoyUKUFS9SwDRANHAgYCV
D5UAswCBwKlAVl4AoKCgKVAwIDUAVVAhAAAeAAAA/QAXTA9jFgEKICAgICAg
AAAA/wBMWjJFRTAwMTQyMDAKAAAA/ABBY2VyIEIyNzZIVUwKAGM=
</data>
  <key>DisplayVendorID</key>
  <integer>1138</integer>
  <key>DisplayProductID</key>
  <integer>865</integer>
</dict>
</plist>

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

require 'base64'

data=`ioreg -l -d0 -w 0 -r -c AppleDisplay`

edids=data.scan(/IODisplayEDID.*?<([a-z0-9]+)>/i).flatten
vendorids=data.scan(/DisplayVendorID.*?([0-9]+)/i).flatten
productids=data.scan(/DisplayProductID.*?([0-9]+)/i).flatten

displays = []
edids.each_with_index do |edid, i|
    disp = { "edid_hex"=>edid, "vendorid"=>vendorids[i].to_i, "productid"=>productids[i].to_i }
    displays.push(disp)
end

# Process all displays
if displays.length > 1
    puts "Found %d displays!  You should only install the override file for the one which" % displays.length
    puts "is giving you problems.","\n"
end
displays.each do |disp|
# Retrieve monitor model from EDID data
monitor_name=[disp["edid_hex"].match(/000000fc00(.*?)0a/){|m|m[1]}.to_s].pack("H*")
if monitor_name.empty?
    monitor_name = "Display"
end

puts "found display '#{monitor_name}': vendorid #{disp["vendorid"]}, productid #{disp["productid"]}, EDID:\n#{disp["edid_hex"]}"

bytes=disp["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" % disp["vendorid"]) rescue nil
f = File.open("DisplayVendorID-%x/DisplayProductID-%x" % [disp["vendorid"], disp["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>#{monitor_name} - forced RGB mode (EDID override)</string>
  <key>IODisplayEDID</key>
  <data>#{Base64.encode64(bytes.pack('C*'))}</data>
  <key>DisplayVendorID</key>
  <integer>#{disp["vendorid"]}</integer>
  <key>DisplayProductID</key>
  <integer>#{disp["productid"]}</integer>
</dict>
</plist>"
f.close
puts "\n"
end		# displays.each

I've just like to thank you. My ASUS monitor suddenly became usable in Mac OS X!

Thank you. You saved my day. For the record, I have an Acer B276HUL (like yours) and El Capitan instructions work with High Sierra too.

Much appreciated! Every time I upgrade my Mac I realize that I need to run this again.