Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!zaphod.mps.ohio-state.edu!think!snorkelwacker!bloom-beacon!EXPO.LCS.MIT.EDU!rws
From: rws@EXPO.LCS.MIT.EDU (Bob Scheifler)
Newsgroups: comp.windows.x
Subject: Re: Do Servers Perform Gamma Correction?
Message-ID: <9002192154.AA01862@expire.lcs.mit.edu>
Date: 19 Feb 90 21:54:11 GMT
References: <2803@polstra.UUCP>
Sender: daemon@athena.mit.edu (Mr Background)
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    The description of the XColor structure in the XLIB book seems to imply
    that the RGB values correspond linearly to the intensities on the
    display.

The implication is wrong (Xlib probably should be reworded).  The server does
not do gamma correction.


    Somebody (server or client) has to perform intensity correction, and it
    seems clear that the server, which knows the characteristics of the
    display, is the obvious choice.

There is some discussion going on in the ximage mailing list about gamma
correction and where it should be done.  Saying it should *always* be done
isn't necessarily the right answer either.  The real problem I think, for most
applications, stems from the use of an inherently device-dependent color model
(RGB) as the only interface.  A device independent color model (e.g. the HVC
model that Tektronix presented at a past X conference) would be a better
solution than introducing gamma correction.