From: Richard Stallman <rms@gnu.org>
Cc: emacs-devel@gnu.org
Subject: Re: PNG pictures have gamma correction twice applied
Date: Thu, 07 Nov 2002 10:08:45 -0500 [thread overview]
Message-ID: <E189oGz-0007ti-00@fencepost.gnu.org> (raw)
In-Reply-To: <200211061556.gA6FuCU6005082@localhost.localdomain> (David.Kastrup@t-online.de)
When a PNG image is displayed, first all the gamma correction factors
of the screen and image are taken into account, and the PNG library
is called with that information. The resulting color triples are in
properly gamma-adjusted 24bit color space, ready for putting on the
screen.
Is the same thing true for other image formats, or only for PNG?
Then Emacs looks up every pixel in a lookup table, and if it
does not find it there, it again does gamma correction and other
stuff.
The fix would seem to be to delete the second gamma correction. The
two hard questions are (1) where this code is and (2) whether the
change needs to be made for all image formats or just for PNG.
It sounds like you know the answer to (1). Could you tell us?
Would someone like to investigate the answer to (2)?
next parent reply other threads:[~2002-11-07 15:08 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200211061556.gA6FuCU6005082@localhost.localdomain>
2002-11-07 15:08 ` Richard Stallman [this message]
2002-11-09 22:40 ` PNG pictures have gamma correction twice applied David Kastrup
2002-11-11 10:20 ` Richard Stallman
2002-11-30 13:36 ` David Kastrup
2002-12-03 14:59 ` Richard Stallman
2002-12-03 15:21 ` David Kastrup
2002-12-05 15:08 ` Richard Stallman
2002-12-05 15:34 ` David Kastrup
2002-12-05 17:31 ` David Kastrup
2002-12-06 15:52 ` Richard Stallman
2002-12-06 16:01 ` David Kastrup
2002-11-11 16:58 ` Stefan Monnier
2002-11-11 17:30 ` David Kastrup
2002-11-11 17:43 ` Stefan Monnier
2002-11-18 11:31 ` David Kastrup
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