Re: [OT] Dot shape prevalence
Re: [OT] Dot shape prevalence
- Subject: Re: [OT] Dot shape prevalence
- From: Glenn Huish <email@hidden>
- Date: Thu, 06 Oct 2005 11:55:20 -0700
Roger Breton wrote:
I'm doing an informal survey about which halftone dot shape has gained
widespread acceptance in printing these days? Is it Eucledian or Elliptical?
I suspect Eucledian is probably more widespread because it is the default
dot shape in most PostScript RIP. But I can't say for sure.
Euclidian certainly seems to be the default for many systems, but I
think it's a poor choice for fleshtones. It's a symmetrical, square
midtone dot, with a 4-way corner join. Makes for nasty tone jumps, any
time i've had to play with it. And if i remember right, i think it's
usually implented with a simple dot growth algorithm, giving star-shaped
reverse dots in shadows, instead of round reverse (white) dots. Ugly.
I've had much better luck with elliptical dots for fleshtone work.
Although I still miss Scitex Composite dots. (sigh...)
And what is the current practice when printing portraits and skintone: I
gather that placing the magenta in the angle of the black gives "better"
results. Is there any truth to this? Or is that all taken care by the more
advanced screening techniques such as Irrational Tangent?
M/K swap works fine, as does twiddling the yellow screen frequency, or
plotting Y using stochastic screening. I haven't found any normal AM
screening, no matter how advanced, which overcomes the reality of the 15
degree moire.
I was searching through the SWOP 10th Edition booklet in the hope that it
would have a recommendation on screening but, alas, nothing. Unless I missed
it :(
I know I've seen something somewhere, but it might be in the
certification kit. I'll look around, see what I find.
g++
--
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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