Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!rutgers!columbia!cs!djk
From: djk@cs.cs.columbia.edu (David Kurlander)
Newsgroups: comp.graphics
Subject: Re: Looking for Slide Makers
Message-ID: 
Date: 16 Aug 89 18:44:32 GMT
References: <19243.24E6C3DF@urchin.fidonet.org> <11605@cit-vax.Caltech.Edu>
Organization: Columbia University Computer Science
Lines: 21
In-reply-to: kalra@rodan.caltech.edu's message of 15 Aug 89 21:14:45 GMT

In article <11605@cit-vax.Caltech.Edu> kalra@rodan.caltech.edu (Devendra Kalra) writes:
>  A few years ago, I played with the Matrix QCR-D model. I noticed serious 
>  banding problems. I seemed to be getting only 6 bits of resolution
>  rather than the 8 that it advertised.
>  Any comments?

We also get only 6 bits of color resolution out of our Matrix QCR-D
film recorder.  If you examine the tables that map input intensity to
colors for this device, you'll see that several input values are often
mapped to a single output value.  I wrote a program which uses the
Floyd Steinberg error propagation algorithm to compensate for the
QCR-D's standard lookup table.  The results are significantly better
-- banding is often no longer a problem, and is always significantly
reduced.  The folks at NYIT use a similar approach.  Still, it would
be nice to have a full 8 bits of output!

David
--
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David Kurlander				Department of Computer Science
djk@cs.columbia.edu			Columbia University