Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!apple!ftanaka
From: ftanaka@Apple.COM (Forrest Tanaka)
Newsgroups: comp.sys.mac.hardware
Subject: Re: Mac IIci onboard video and gamma correction?
Keywords: IIci video gamma
Message-ID: <37037@apple.Apple.COM>
Date: 6 Dec 89 15:55:23 GMT
References: <5200@okstate.UUCP>
Distribution: usa
Organization: Apple Computer Inc, Cupertino, CA
Lines: 53

In article <5200@okstate.UUCP> norman@a.cs.okstate.edu (Norman Graham) writes:

+--------
|In the Monitors cdev, there's a checkbox titled 'Use Special Gamma'.
|(To find it, hold down the option key and ckick the 'Options...' button.)
|It installs some kind of gamma correction, but what does that mean?
|How does it effect my system?  I assume that it has something to do
|with the color tables.
+--------

The human eye doesn't respond to brightness linearly.  Dark scenes appear
darker to humans than they should be.  As a scene becomes brighter, the human
eye catches up with reality.  Time for graphs:

            ^
            |              *
            |              *
            |             *
    Actual  |             *
Brightness  |            *
            |           *
            |         **
            |       **
            |    ***
            |****
            +------------------->
             Apparent Brightness

Gamma correction linearizes the response of the human eye by artifically
boosting low brightness levels.  The effect can be subtle, but you should be
able to see some difference.  Uncorrected Gamma means that low brightness
levels will not be boosted and your eyes will have to fend for itself.
Standard Gamma will boost the low brightness levels.  You should normally
use this setting.  If you photograph the screen, you might want to use the
uncorrected gamma setting because photographic film's response is much more
linear.

+--------
|Norman Graham                            Oklahoma State University
|  Internet:  norman@a.cs.okstate.edu     Computing and Information Sciences
|      UUCP:  {cbosgd, rutgers}           219 Mathematical Sciences Building
|              !okstate!norman            Stillwater, OK  USA  74078-0599
+--------


-- 
*******************************************************************************
Forrest Tanaka                            Macintosh Developer Technical Support
Internet:  ftanaka@apple.com                               Apple Computer, Inc.
      or:  Forrest_Tanaka.DTS@gateway.qm.apple.com
AppleLink: TANAKA                                         Do extra-terrestrials
Phone:     (408) 974-1243                                       believe in God?
*******************************************************************************