From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@cse.psu.edu
Subject: Re: [9fans] colormap
From: okamoto@granite.cias.osakafu-u.ac.jp
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Date: Thu,  1 Mar 2001 18:35:41 +0900
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>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