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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

caiceA commented May 23, 2017

i have mac siri will this work for me ? i just bought samsung curved 27" F396 the font is not shart enough

da1z commented Dec 25, 2017

I can not create folder under /System/Library/Displays/
mkdir: Ovverides: Operation not permitted

please advise

askarsyzdykov commented Jan 11, 2018

you need to reboot your mac and press ⌘+R when booting up. Then go into Utilities > Terminal and type the following commands:

csrutil disable

anirudha commented Jan 17, 2018

step 3 for el capitan and above /System/Library/Displays/Contents/Resources/Overrides/

sudo cp -R DisplayVendorID-5e3 /System/Library/Displays/Contents/Resources/Overrides/.

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