Re: [OT] Dot shape prevalence
Re: [OT] Dot shape prevalence
- Subject: Re: [OT] Dot shape prevalence
- From: Glenn Huish <email@hidden>
- Date: Fri, 07 Oct 2005 14:10:45 -0700
Yes, Scitex- imagesetters, not scanners. You're dating yourself... :)
Class Screening is/was their hardware-based screening algorithm, used by
all (i think?) of their imagesetters by the late 90's. Everyone prefers
what they know, i imagine, and this is simply my opinion, but since you
asked (and besides, these debates are always fun...)
As Matt mentioned, You could build a screenset at any frequency you
wanted, using a simple, vendor supplied spreadsheet. While you're at
it, go ahead and assign essentially any angle you want on the 360 degree
axis (we tend to use 7.5 degree shifts), infinitely adjust the ratio of
dot length to width, and if all else fails and you *still* got hard
breaks somewhere, add any amount of noise you need if you just need to
break up the regularity of the screen a bit.
Composite Dot was simply an improvment on the Euclidian-style dot: round
at either end of the scale, highly adjustable ellipse in the middle.
<soapbox>
I really did and still do consider Class Screening to represent a true
pinnacle of imaging quality- Superior to the all the earlier screening
technologies (you mentioned Hell and it's quirks, Agfa systems never got
the quality I needed- Screen and Barco worked fairly well, but
Postscript screening was barbaric). Other parts of the Scitex workflows
were certainly lacking, but I was consistently amazed at the flexibility
we had to build any kind of screenset we needed, from 250 line all the
way down to 33, and get perfect, moire free output. The 1-bit TIFF based
junk that passes for quality output in current workflows seems like a
huge step backwards to me- powerful for it's ability to open up
workflows and drive many different kinds of output, but quality? Not
part of the equation.
This is one one those issues which, to me, illustrates that all the R&D,
all the money, all the push toward new technologies and focus of all the
brilliant minds in this truly enormous industry, and therefore every
leap forward in technology, is and will always be focused on making
things *faster* and *cheaper*, but never on *better*, except as a
by-product of accomplishing the first two.
What if all of the astounding, incredible leaps in printing industry
technology over the last 20 years were focused purely on making better
prints? On printing better images than were ever possible before?
Oh well, enough...
</soapbox>
Richard Corbett wrote:
...
What's all this about Scitex dots. This organization never produced a drum
scanner, and although at one time they produced a large expose drum there
were never many of them sold because the major three scanner manufacturers -
for whom Scitex had to provide interfaces in order to utilize their scanner
input facility - had their own expose units as part of their scanner
packages.
Are you sure you are not confusing Scitex with Hell who had a most unusual
dot shape - rather like freshly dug potatoes - and brought about by their
inability to produce 30 degree screen angles which in turn produced a most
noticeable and entirely unorthodox rosette.
--
Glenn A. Huish
Chief Technical Officer
Bel Aire Displays
5710 Hollis St.
Emeryville, CA 94608
510.654.0964 x27
http://www.belairedisplays.com
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