1993-10-22 - Re: Canon copiers

Header Data

From: “Robert J. Woodhead” <trebor@foretune.co.jp>
To: peb@PROCASE.COM (Paul Baclace)
Message Hash: 443a03dbecb488e787ee983486c061723fdd6783363bbd30667b7e6cad1880b6
Message ID: <9310220156.AA27328@dink.foretune.co.jp>
Reply To: <9310212323.AA04196@banff.procase.com>
UTC Datetime: 1993-10-22 01:58:04 UTC
Raw Date: Thu, 21 Oct 93 18:58:04 PDT

Raw message

From: "Robert J. Woodhead" <trebor@foretune.co.jp>
Date: Thu, 21 Oct 93 18:58:04 PDT
To: peb@PROCASE.COM (Paul Baclace)
Subject: Re: Canon copiers
In-Reply-To: <9310212323.AA04196@banff.procase.com>
Message-ID: <9310220156.AA27328@dink.foretune.co.jp>
MIME-Version: 1.0
Content-Type: text/plain


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.







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