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Last active June 17, 2024 02:39
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# Create display override file to force Mac OS X to use RGB mode for Display
# see
require 'base64'
data=`ioreg -l -d0 -w 0 -r -c AppleDisplay`
displays = []
edids.each_with_index do |edid, i|
disp = { "edid_hex"=>edid, "vendorid"=>vendorids[i].to_i, "productid"=>productids[i].to_i }
# 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"
elsif displays.length == 0
puts "No display data found! Are any external displays connected?"
puts "\nNote: Apple Silicon (arm64) devices are currently unsupported, as the standard"
puts "method of retrieving display information does not work."
displays.each do |disp|
# Retrieve monitor model from EDID display descriptor
i = disp["edid_hex"].index('000000fc00')
if i.nil?
monitor_name = "Display"
# The monitor name is stored in (up to) 13 bytes of text following 00 00 00 fc 00.
# If the name is shorter than 13 bytes, it is terminated with a newline (0a) and then padded with spaces.
monitor_name = [disp["edid_hex"][i + 10, 26].to_s].pack("H*")
monitor_name.rstrip! # remove trailing newline/spaces
puts "Found display '#{monitor_name}': vendor ID=#{disp["vendorid"]} (0x%x), product ID=#{disp["productid"]} (0x%x)" %
[disp["vendorid"], disp["productid"]]
puts "Raw EDID data:\n#{disp["edid_hex"]}"
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 "Recalculated checksum: 0x%x" % bytes[127]
puts "new EDID:\n#{{|b|"%02X"%b}.join}"
Dir.mkdir("DisplayVendorID-%x" % disp["vendorid"]) rescue nil
filename = "DisplayVendorID-%x/DisplayProductID-%x" % [disp["vendorid"], disp["productid"]]
puts "Output file: #{Dir.pwd}/#{filename}"
f =, 'w')
f.write '<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "">
<plist version="1.0">'
f.write "
<string>#{monitor_name} - forced RGB mode (EDID override)</string>
puts "\n"
end # displays.each
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joevt commented Oct 15, 2023

@anbarae What display? Is it HDMI or DisplayPort connection? Try SwitchResX? Run AllRez to get a list of display modes.

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Works for Sonoma on a 2016 Macbook Pro 👌

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anbarae commented Oct 25, 2023 via email

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I have 2 external HDMI-to-usbc monitors. The override works and I can see it take effect in Settings > Displays, but when i rearrange the monitors in Display settings, one of the monitors gets blurry again. Anyone run into this?

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