From: okamoto@granite.cias.osakafu-u.ac.jp
To: 9fans@cse.psu.edu
Subject: Re: [9fans] colormap
Date: Thu, 1 Mar 2001 18:35:41 +0900 [thread overview]
Message-ID: <20010301093616.0850E199EA@mail.cse.psu.edu> (raw)
>Your m8 image shows colors on the true-color display because
>you've lied about the channel format, saying it's color.
Yes, we lied the Plan 9 kernel. However, isn't it posssible to use another
colormap to change colormap to rgb by cmap2rgb(), which assumes only
rgbv colormap?
Without this lie, we have no chance to see 256 greyscale images on
8 bit display... I found some codes in /sys/src/libdraw/rgb.c assuming
only 16 shades of greyscale, which made us disappointed.
Our local "lie and broken promise" method is as follows: ^_^
To check what display depth we are in, and
(1) if we are on 8 bit display, make m8 'greyscale' data, and change colormap
to one having 256 grey shades, such as /lib/cmap/c7291.56.
(2) if we are on truecolor display, make k8 'greyscale' data.
We tried (r8g8b8) with same three bytes data, but it's just waste of memory. :-)
Kenji
next reply other threads:[~2001-03-01 9:35 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2001-03-01 9:35 okamoto [this message]
-- strict thread matches above, loose matches on Subject: below --
2001-03-01 8:41 Russ Cox
2001-03-01 8:15 okamoto
2001-03-01 1:52 okamoto
2001-02-28 6:52 okamoto
2001-02-28 6:55 ` Scott Schwartz
2001-02-28 6:26 Russ Cox
2001-02-28 6:02 okamoto
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