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[filmscanners] RE: Density vs Dynamic range>AUSTIN (2a)



This is nonsense. A steady DC voltage contains an amount of information
equal to log2 n, where n is the number of different DC voltages that can be
distinguished by the receiver. It conveys this information even if it
remains unchanged for a million years. This information is exactly what is
displayed by a DC voltmeter.

If you think this information is useless, try capacitively coupling the
output of the CCD in a scanner, to eliminate the DC. You'll of course find
that the scanner becomes useless, because it can no longer distinguish
between an all-white target and an all-black target.

--

Ciao,               Paul D. DeRocco
Paul                mailto:pderocco@ix.netcom.com

> From: Anthony Atkielski
>
> But samples are not signals, and DC is not a signal.  A current or voltage
> that does not vary (i.e., DC) carries no information, and is thus not a
> signal.  All signals are AC.  More precisely, all signals vary
> over time; DC
> does not vary over time; therefore DC and signals are mutually exclusive.

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