Path: utzoo!utgpu!water!watmath!clyde!bellcore!decvax!mcnc!gatech!bloom-beacon!tut.cis.ohio-state.edu!pike!mills-cl
From: mills-cl@pike.cis.ohio-state.edu (christopher mills)
Newsgroups: comp.sys.amiga.tech
Subject: Re: 32 shades of gray
Keywords: gray scale
Message-ID: <7941@tut.cis.ohio-state.edu>
Date: 8 Mar 88 17:23:57 GMT
References: <2801@gryphon.CTS.COM>
Sender: news@tut.cis.ohio-state.edu
Organization: The Ohio State University Dept of Computer and Information Science
Lines: 50

In article <2801@gryphon.CTS.COM> richard@gryphon.CTS.COM (Richard Sexton) writes:

>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):

...

>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)

...

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


	Not so big of a secret.  My first ray-tracing attempts were in black
and white, 640 x 400, 16 shades of grey with a 2 x 2 dither patern, giving
(as I recall) 61 shades of grey.  It looked pretty good...

					Chris

-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
 _____________________           |     Christopher Mills.
(_)________________   \          |     mills-cl@polaris.cis.ohio-state.edu
  ________________|\   \         |     Current Thought: I'm looking for a
 (_)______________\_\   \        |          job.  Need a brilliant MSEE?
   ______________________\       |          (I don't do windows).
  (_)____________________|       |     DISCLAMER: I really wish I could blame
                                 |          my thoughts on someone else...
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