bastibense/README.md

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    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:


Download patch-edid.rb from http://embdev.net/attachment/168316/patch-edid.rb


Execute in Terminal (without the $):
$ ruby patch-edid.rb


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


Reconnect the Display


Enjoy


## genedid.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
	#!/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