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Re: Canon copiers

To: [email protected] (Paul Baclace)
Subject: Re: Canon copiers
From: "Robert J. Woodhead" <[email protected]>
Date: Fri, 22 Oct 93 10:56:03 JST
Cc: [email protected], [email protected], [email protected]
In-Reply-To: Your message of Thu, 21 Oct 93 16:23:15 -0700. <[email protected]>

Paul writes:

>I'd like to know how they put the serial number into the copy.

Most likely by modulating the Least Significant Bit of the color
intensity in some (or all) color-filled areas of the image.  A
set of sync-bits, serial number, and some more sync bits.  Repeat
every line, shifted by 1 bit, and you'll get a pattern that is
hard to differentiate from the background unless you _know_
what to look for.

I wouldn't be surprised if there isn't a time and date stamp
as well, plus batch # info.

References:
- Re: Canon copiers
  - From: [email protected] (Paul Baclace)

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