Archived posting to the Leica Users Group, 2001/07/23

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Subject: Re: [Leica] Re: Digital Leica and reality
From: "Mxsmanic" <mxsmanic@hotmail.com>
Date: Tue, 24 Jul 2001 04:51:09 +0200
References: <001101c113d1$95a81dc0$0201a8c0@Workgroup>

Frank Filippone writes:

> OK.. it invents DOTS of ink.. so what is the
> difference other than a technical definition..

The difference is huge.  Machine dots are spots of ink.  Pixels are picture
elements.  A pixel consists typically of many machine dots; for example, if you
want 256 gray levels in an image, you need 256 machine dots per pixel, which
corresponds to a square roughly 8x8 machine dots in size for each pixel.  If
your printer can resolve a maximum of 1440 machine dots per inch, then, the
maximum number of pixels per inch that it can print (with 256 gray levels, in
monochrome) is 180.

This is for printers using opaque dots, which includes ink-jet printers and
offset printing with fixed or stochastic screens.  For transparent dots of dye,
such as those used in dye-sublimation printers and chemical printing processes,
machine dots and pixels usually correspond on roughly a one-to-one basis.

> The multitude need to understand clearly that
> a true 1:1 correlation of captured pixels to
> printed pixels does not happen in a digital
> enlargement..

This is incorrect.  The correlation is usually 1:1, in fact, unless the image is
interpolated or downsampled.

> It does so happen in wet prints.

Chemical prints generally do not use dots or pixels at all (except for systems
like the Fuji Frontier).

> Where do the extra digital pixels come from?
> A math algorithim.

For interpolation, yes.

What is your point, exactly?

In reply to: Message from "Frank Filippone" <red735i@earthlink.net> (RE: [Leica] Re: Digital Leica and reality)