RE: [Algorithms] 256 colour palette

[Sasha P. <sa...@pr...>]

Hi Matt,

One way to go is to use so-called "6-6-6" palette, which gives you 6 shades
of red, green and blue color. You basically divide 255 by 6, and ~42 is your
shade step. This means, colors in your palette are:

0, 0, 0
0, 0, 42
0, 0, 85 (I rounded up here)
...
0, 42, 0
0, 42, 42
0, 42, 85
...
255, 255, 255

6-6-6 palette takes 216 colors, this is good for Windows as you still have
room for standard Windows colors. If you don't care about this, you can use
6-7-6 palette, having 7 shades for green, this takes 252 colors.

Such palettes are good because when you need to find nearest palette index
for a given 24-bit RGB color, you don't search for the nearest color,
instead you calculate it using trivial math:
Rindex = R / (255 / 6);
Gindex = G / (255 / 6);
Bindex = B / (255 / 6);

And then something like (Rindex * 6 * 6) + Gindex * 6 + Bindex gives you the
palette index. I hope I didn't make any mistakes in math here, but anyway
you should get the idea! :)

Regards,

Sasha Prokhorov.
(sa...@pr.../ICQ 4772797)

-----Original Message-----
From: Matthew Davies [mailto:MD...@ac...]
Sent: Wednesday, August 30, 2000 10:40 AM
To: Algorithms List (E-mail)
Subject: [Algorithms] 256 colour palette


Hi,
 
Can any of you guys give me some hints on choosing a decent 256 colour
palette so that I can get a nice spread of colours.  I need it for a simple
3d game so basically I need to cover common colours and shades thereof.  
 
Do any of you have experience in this area.  I've had it so easy with 24-bit
graphics up until now!  :-)
 
Thanks in advance for any help that you might provide.
 
Cheers!
Matt Davies
Programmer
Acclaim Studios, Cheltenham
+44 (0) 1242 533682
ICQ: 78711743