Digital BW, The Print

----- Original Message -----
From: "Anthony Atkielski" <atkielski@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Friday, August 02, 2002 12:07 AM
Subject: Re: [Digital BW] Storage of digital images


> Bob writes:

> Inkjet printers, like offset presses, use essentially opaque inks in four
or
> more colors, usually cyan, yellow, magenta, and black.  Since these inks
are
> opaque, their darknesss on paper cannot be varied, nor can one color be
> printed on top of another to blend the two.  So, in order to create
> variations in the darkness of the printing, the inks must be divided into
> dots of variable size.  When the dots are large and closely spaced, the
> printing appears dark (from a suitable distance).  When the dots are small
> and widely spaced, the printing appears light.

Anthony, substitute 'essentialy opaque' for 'almost transparant'. Then start
all over again.
Even silkscreen printing uses transparent inks when printing CMYK full
colour work.
Read about droplet size differences and how they are applied in inkjet
printing.
The Iris prints are for 90% built on transparent inklayer thickness
differences.
Better compare inkjet printing with stochastic screen printing or in the
Iris case with rotogravure printing,
comparing it with conventional offset or autotype raster printing doesn't
work. And that also means that the ppi/dpi relation is of another order than
the ppi/lpi relation.

Tone differences and by that colourmixing can be achieved in several ways:
dot size variation, dot frequency, ink layer thickness. They all are used in
inkjet printing and sometimes all of them in one print. They all rely on
transparent inks.

Only in monochrome raster (dotsize) printing it would be possible to use
opaque inks and even there it isn't used for technical reasons.

Easiest method is getting a loupe and examples of different printing
systems.

Ernst