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Fix blurry fonts on some external monitors when using MacBook Pro Retina

How to fix blurry fonts on some external monitors when using MacBook Pro Retina

It seems that graphcis and fonts look rather blurry on some monitors when hooked up to a MacBook Pro (Retina). This might fix the issue for you:

  1. Download patch-edid.rb from

  2. Execute in Terminal (without the $):

    $ ruby patch-edid.rb

  3. Copy produced folder (example: DisplayVendorID-22f0) to /System/Library/Displays/Overrides (authorize if needed, if the folder exists, backup it before)

  4. Reconnect the Display

  5. Enjoy

# Create display override file to force Mac OS X to use RGB mode for Display
# see
# Update 2013-06-24: added -w0 option to prevent truncated lines
require 'base64'
data=`ioreg -l -w0 -d0 -r -c AppleDisplay`
puts "found display: vendorid #{vendorid}, productid #{productid}, EDID:\n#{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" % vendorid) rescue nil
f ="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" "">
<plist version="1.0">'
f.write "
<string>Display with forced RGB mode (EDID override)</string>

didn't make a difference.

bitbut commented Jun 3, 2016

ruby patch-edid.rb
patch-edid.rb:11:in <main>': undefined method[]' for nil:NilClass (NoMethodError)

On mac os X El Capitan

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