Wayde Allen (wallen@boulder.nist.gov)
Wed, 13 Jan 1999 14:48:20 -0700 (MST)
Here is the answer I got for the another one of the questions posted on
the list.
- Wayde
(wallen@boulder.nist.gov)
---------- Forwarded message ----------
Date: Wed, 13 Jan 1999 12:48:08 -0700
From: Randy Little <rlittle@rslittle.com>
To: Wayde Allen <wallen@boulder.nist.gov>
Subject: Re: Continuous Tone? (was Re: Pt/Pd vs Gum???) (fwd)
> Wow, if I had access to a 36,000 dpi imagesetter (thousand?!), I'd sure
> go for more than a300 line screen negative! Using the RULE OF SIXTEEN (to
> calculate what line screen frequency for a given imagesetter resolution
> will provide all 256 shades of gray), you divide 36,000 by 16 and get a
> line screen of 2,250. I have a hard time even imagining a dot (and one
> that can assume 256 different SHAPES at that) at that ruling.
>
> Where the dickens does he find these 36,000 dpi imagesetters? It's hard
> enough to find the 4,800 ones!
You don't, they never made it to market apparently. They where
Developmental and died when 1st and 2nd order stochastic became the way.
They where designed to help element Moiré and give higher bit depth like
36 and 48 bit color depth not 24 bit.
Film is fast dying in the press world and HD requires half the dots of
Rosette screens.
The below is how things work in terms of size.
Creo has an image setter that makes a 9.5micron dot.(this is a square dot.)
think about how many of those fit in an halftone dot that is 108microns
square. (11664) but it was deemed not necessary when crystal raster and HD
screening came into being since the require less resolution since they are a
random pattern.
Kodak makes a plate that holds a 4.5 micron dot.
Scitex HD uses a Gaussian dot (soft edges) at about 11 microns.
-- Randy Little R.S.Little Studio Photography & Digital Imaging http://www.rslittle.comRepresented by:
Carol Guenzi Agents http://www.artagent.com
Jim Zaccaro & Assoc. http://home.earthlink.net/~jimzacc
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