Dell U3014 모니터 Mac OSX 에서 sharpening or contrast enhancement 문제 해결

출처1: http://embdev.net/topic/284710

출처2: http://ireckon.net/2013/03/force-rgb-mode-in-mac-os-x-to-fix-the-picture-quality-of-an-external-monitor

준비: 

patch-edid.rb

원인:

Many Dell monitors (e.g., U2713H, U2713HM, ...) look really bad when 
connected to a Mac (OS X 10.8.2) via DisplayPort, as if some sharpening 
or contrast enhancement was applied. Others have reported the same 
problem 
(http://www.anandtech.com/show/6308/dell-u2713hm-un..., 
http://forums.macrumors.com/showthread.php?t=1481582). The reason is 
that the DisplayPort uses YCbCr colors instead of RGB to drive the 
display, which limits the range of colors and apparently causes the 
display to apply some undesired post processing.

The problem can be solved by overriding the EDID data of the display

해결 방법:

How to force RGB in Mac OS X

1. Download the patch-edid.rb script from the forums thread above and put it in your home directory.
2. Connect only the external monitor(s) in question (I closed my MacBook lid, for example). The script will make override files for any connected monitor.
3. Type “ruby patch-edid.rb” in Terminal.
4. A new folder will be created in your home directory. Move it into the “/System/Library/Displays/Overrides” folder. If Finder tells you that you are overwriting an existing folder, consider backing it up first.
5. Restart your computer, enjoy your monitor.

To undo the changes, either delete the folder you had copied to the Overrides folder (if it didn’t already exist) or replace it with the folder you had backed up.

다른 방법: 

DisplayVendorID-10ac.zip

위의 방법으로 생성된 EDID override 설정파일을 다운 받아 /System/Library/Displays/Overrides/DisplayVendorID-10ac 에 압축을 푼다.