Path: utzoo!utgpu!water!watmath!clyde!rutgers!psuvax1!burdvax!sdcrdcf!trwrb!cadovax!gryphon!richard
From: richard@gryphon.CTS.COM (Richard Sexton)
Newsgroups: comp.sys.amiga.tech
Subject: 32 shades of gray
Keywords: gray scale
Message-ID: <2801@gryphon.CTS.COM>
Date: 8 Mar 88 01:50:32 GMT
Organization: Trailing Edge Technology, Redondo Beach, Ca.
Lines: 55
Posted: Mon Mar  7 17:50:32 1988

(Love the new group, guys.  Can we make it last ?)

Alright, I'm letting you guys in on one of my secrets.

I've been using this tip to acheive what looks for all the world
like 32 gray scales.

First you make a stack of 16 bars, in colors 0 - 15 with rgb values
from (0,0,0) to (15,15,15):

  +----------+
  |   0      |
  +----------+
  |   1      |
  +----------+
	.
	.
	.
  +----------+
  |   15     +
  +----------+

with 0 being (0,0,0) and 15 being (15,15,15)

Now, to get the additional 16 shades of gray, dither 1:1 between
every n'th color and it's n+1'th counterpart. Use the following pattern:


       * * * * * * * * * *
        * * * * * * * * * *
       * * * * * * * * * * 

So color 0 (of 32) is pure color 0.

Color 1 (of 32) is color 0 and color 1 (of 16) dithered with a 50% duty cycle.

Color 2 (of 32) is pure color 1 (of 16)

.
.
.

etc.


Hmm. this is easier to do than explain. I will mail or post a small 
brush done with this technique is it is requested.

It's a nice trick which yields smoother looking continuous tones.


-- 
                      "...(alright Nils, alright)..."
                          richard@gryphon.CTS.COM 
   {ihnp4!scgvaxd!cadovax, rutgers!marque, codas!ddsw1} gryphon!richard