Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!ames!vsi1!octopus!avsd!childers
From: childers@avsd.UUCP (Richard Childers)
Newsgroups: comp.graphics
Subject: Re: Color desktop scanners (a technical discussion begins)
Message-ID: <1875@avsd.UUCP>
Date: 2 Aug 89 22:54:26 GMT
References: <1869@ucsd.EDU>
Reply-To: childers@avsd.UUCP (Richard Childers)
Organization: Metaprogrammers International
Lines: 97

rich@net1.ucsd.edu (bmf) writes:

> Problem: 
>	Creating a desktop color scanner which is easy to use, has
>	the quality of a drum scanner , and costs less than $3000 in
>	parts. If we keep the discussion public we all gain a public
>	domain scanner.
				.
				.
				.

> Conclusion:
>	You can do a good job with todays scanners but what about
>	applying some other technologies. Are there CD lasers
>	available in a variety of wavelengths? How about focusing
>	one of the spectral analysis devices onto a ccd array and
>	any diode which shows a response gets added into the color
>	value of the current pixel being scanned (too slow huh?).
>	This could be fun.

This is all very interesting, as I was peripherally involved in such a 
project several years ago. An individual whom was peripherally involved
in printing, and some shadowy partners, wanted to be the first people
to provide tabletop printing-quality-resolution scanning and reproduction
systems. I provided the organizing element to an otherwise incoherent
plan to become millionaires, such that the algorithm we evolved after
much discussion resembled yours in approach, although we foundered long
before we reached the point of actually researching the interesting
details, for lack of responsible funding.

Getting a scanning resolution of 1/1000th of an inch was the major problem.
For some reason, the senior financing partner wanted to have everything
written in PostScript, but properly speaking, the accounting and control
software would have been written in another language, more suited, and the
PostScript would have been restricted to the image-processing module.

There were three problems.

	(1)	Create a device which attaches to a CPU, via SCSI, or
		RS232, or whatever, that translates a physical image
		into a series of bitmaps corresponding to the various
		major colors.

	(2)	Create and implement algorithms suitable to translating
		the major colors, from the physicist's point of view,
		into the complementary color set, as seen from the ink-
		driven view of the printer.

	(3)	Create and implement algorithms to translate vast bitmaps
		into a series of concise and minimalist PostScript language
		descriptions of the image contained, perfectly.

This particular thread represents a discussion on problem (1). ( When we were
talking about this, I was pretty sure monochromatic lasers were the light
source to use, and I'm pleased to see my guess confirmed. )

I've seen many discussions that address the issues around problem (2), and
I've learned quite a lot that I was unable to ferret out of libraries, by
the way, while reading them.

Problem (3) doesn't seem that hard to me, sort of a compiler problem, but
instead of dealing with textual icons you'd be dealing with geometric ones,
probably hexagons and triangles to fill up all the available spaces, then
lines where possible, then point-specific statements, the idea being to
crunch the huge bitmap down to the smallest PostScript description possible,
unless time constraints forced a tradeoff between time and space. ( A small
PostScript description would pay off in the reproduction phase, though, or so
I assume, perhaps naively. )

There's also a level somewhere in here, probably 1.5, where after you've
scanned in the image, but before you've separated it, where you might find
it convenient to scale it, crop it, rotate it and in general engage in an
additional layer of layout operations before submitting the job for printing.
This would require a high-density monitor, though, and even the best of the
monitors available for the Mac II ( we got one as a potential platform ) was
inadequate for the job, realistically speaking. This may still be a hitch to
serious layout and graphic design software, by the way. It's good resolution,
but not _great_ resolution, not _invisible_ resolution.

I've been waiting for two or three years for something to appear on the
market, but it seems to be the same old 300 DPI laser writers. < Sigh. >

I don't see a public domain scanner getting very far - hardware efforts
need physical proximity or some serious self-discipline on the part of
multiple individuals - but I'm interested in seeing this happen, and I'm
interested in helping, if it comes to some genuine development efforts.

>/*    Rich Stewart   		{dcdwest,ucbvax}!ucsd!net1!rich  */

-- richard


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