Article View: comp.lang.postscript
Article #2249Re: compensating for distortion
From: Dick Dunn
Date: Fri, 01 Jun 1990 15:51
Date: Fri, 01 Jun 1990 15:51
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2296 bytes
woody@chinacat.Unicom.COM (Woody Baker @ Eagle Signal) writes:
> I used to work for a place that sold Copiers. I sold Lasers, and Computers.
> I was told by people whom I trust, that NONE of the photocopiers would
> produce an exact 1 for 1 copy. It was always about 3% off. This (or so
> I was told) is because the treasury department didnot want anyone copying
> anything exactly, for fear of counterfitting...
Foo. I just ran a copy on a relatively high-end copier to check. It is
1:1 on both axes to within better than 0.5%. That's greater accuracy than
the dimensional stability of paper.
The real reason most copiers tend to be off a little is very simple: They
enlarge ever-so-slightly to compensate for positioning error and variation
in paper size, so that you don't see a black line around the extreme edge
of the copy where the edge of the original was.
Laser printers do (as Henry noted) commonly have a pixel aspect ratio not
quite 1:1. But if you're really concerned about that, you can take some
precise measurements and compensate with a transformation matrix, or if
it's an image, compensate in the scanning or conversion.
>...Especialy color copiers.
> They would not release color analog copiers period...
What's a color analog copier? I'm assuming you mean a copier that is
capable of continuous-tone repro (as opposed to high-contrast "line" copy).
What ever would that have to do with counterfeiting?
>...You will note that
> all of the current color copiers use a glossy toner. Also mandated by
> the treasury department.
No, mandated by the process.
What about standard one-color copiers with a selection of toner colors?
Conspiracy theories are fun, but sheeesh!
--
Dick Dunn rcd@ico.isc.com uucp: {ncar,nbires}!ico!rcd (303)449-2870
...Simpler is better.
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Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!munnari.oz.au!uhccux!ames!ncar!ico!rcd From: rcd@ico.isc.com (Dick Dunn) Newsgroups: comp.lang.postscript Subject: Re: compensating for distortion Summary: nothing so nefarious Message-ID: <1990Jun1.155110.3330@ico.isc.com> Date: 1 Jun 90 15:51:10 GMT References: <90May30.095014edt.18974@me.utoronto.ca> <1289@chinacat.Unicom.COM> Organization: Interactive Systems Corporation, Boulder, CO Lines: 41