Archived posting to the Leica Users Group, 2001/07/22

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Subject: RE: [Leica] Re: Digital Leica and reality
From: "Austin Franklin" <darkroom@ix.netcom.com>
Date: Sun, 22 Jul 2001 13:43:29 -0400

> HE also wants to keep the quality of analog
> film, but in a digital world.  This requires a sensor of size 1.5 BILLION
> pixels.

I hate misinformation like this.  It does not take 1.5 BILLION pixels to
give the same quality of output as analog film.

You can also only print digital images, well, digitally, so let's do the
arithmetic, backwards.

Analog film, for the most part, can print a very nice 8"x10"...so let's
upsize that to 13"x19" for the sake of argument.  A very nice B&W printing
system, Piezo, uses a quad tone ink system, and it's own driver to produce
near or equal to, chemical prints.  It needs grayscale data that is 240PPI
up to about 480PPI, and you really don't get much more from it by giving it
more data, especially in a 13"x19" print.

You may say "but the printers print at 1440 or 2160DPI"...yes, they do, but
that's printer dots, not pixel information sent TO the printer...there is
NOT a one to one correspondence between data resolution sent to the printer
driver, and the output resolution.  One is PIXELS per inch, and one is DOTS
per inch.  Printers can only print dots of a single color at each point, so
it takes many dots to represent the tones.

OK, now that that's out of the way, 480PPI for a 13"x19" print is 480PPI x
13" x 480PPI x 19" = 56,908,800 pixels.  A far cry from 1.5 BILLION.