Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cbmvax!raible
From: raible@cbmvax.commodore.com (Bob Raible - LSI Design)
Newsgroups: comp.sys.amiga.graphics
Subject: Re: Greyscales on Amiga
Message-ID: <19847@cbmvax.commodore.com>
Date: 14 Mar 91 04:17:41 GMT
References: <James_Hastings-Trew.2800@tptbbs.UUCP>
Reply-To: raible@cbmvax.commodore.com (Bob Raible - LSI Design)
Organization: Commodore, West Chester, PA
Lines: 33

In article <James_Hastings-Trew.2800@tptbbs.UUCP> James_Hastings-Trew@tptbbs.UUCP (James Hastings-Trew) writes:
>In a message dated Tue 12 Mar 91 04:50, Harvey_taylor@mindlink.uucp (harvey
>wrote:
>
>
> H>     Background: I want to display some large 256 level greyscale
> H>  video samples. The standard Amiga will output only 16 levels.
>
> H>     So, I am trying to figure out the best way to increase the number of
> H>  greyscale levels viewable on the (my) Amiga. So far the candidates
> H>  are:
>
> H>     1) Dithering
> H>     2) GreyScale to HAM  [SHAM, SHAMM, Dynamic whatever]
> H>     3) A colour board
>
>
>A 24 bit colour card should be able to give you a true 256 grey scale
>picture. Other than than, you best bet is dithering - HAM and Dynamic modes
>don't alter the palette available, so still only have 16 greys to work with
>in those modes. 
>
>The Art Department does a very nice job of converting 256 greyscale images to
>16 greys with Floyd-Steinberg dithering. I daresay at hi-res interlace, the
>results would be indistinguishable from real 256 grey once you get it into
>video.

I was was wondering if some software type could check out a theory of
mine. I was thinking that if one twiddled with the lsb's of the 3 guns
one could create more useable greyscales than 16,colors like
RGB=778,788,889,899, etc. One probably notice any chroma artifacts for
many of these shades. Anybody want to give it a whirl. I'd oblige, but I
haven't programmed anything since my undergraduate days(BSEE '77).