Re: Dot Simulation
Re: Dot Simulation
- Subject: Re: Dot Simulation
- From: Ray Maxwell <email@hidden>
- Date: Thu, 15 Jan 2009 10:35:37 -0800
Hi Roger,
More than ten years ago...I was the color scientist at Creo that worked
with Imation, Kodak, Dupont, and Fuji to get the color right on the Creo
Spectrum dot proofer.
The proofer produces a dot on the proof for each and every dot on the
plate. It does a very accurate job of predicting moire that will appear
on the press.
However, the dot on the proof may be a slightly different size to
correct for a different dot gain on the press vs the proofing material.
The pigments used in the proofing materials have spectral
characteristics that are very close to the pigments used in standard
printing inks.
Personally...I predicted that with Square Spot, most printers would move
to stochastic screens. If the screen frequencies are chosen very
carefully, there is no chance of moire. The screens are not random.
They are designed very carefully so that the spacial frequencies of one
color dose not "beat" with the spacial frequencies of another.
With very good stochastic screens, a contone proof can be a very
accurate predictor of color viewed in a D50 viewing booth. Note that
most inkjet pigments are not spectrally the same as the pigments used on
press. Of course the contone proof is much less expensive to produce.
There are many printers who are printing everything from annual reports
to yellow pages using stochastic screens. Many printers no longer use
AM screens. Note that stochastic screens require a very accurate CTP head.
When you use the finer stochastic screens there is good news and bad
news. The good news is that they are more stable on press than an AM
screen. The bad news is that they are very stable and cannot be "moved"
as much on press as a AM screen. This means that you have to make the
plates correctly and not depend on tuning them on press.
My opinions are my own. I am now retired and do not speak in any way
for Creo or Kodak.
Ray Maxwell
Co-Host of "Maxwell's House" on Leo Laporte's "www.twit.tv"
Roger wrote:
Marco,
Even Creo Spectrum CTP, for example, which doubles as a CMYK dot proofer,
cannot make proofs using the same exact dot as on the plate, because of
needed color adjustment on the proof to match a certain press condition. And
I must say, some prepress houses are adamant about showing dot on their
proofs to their clients, especially in the garment industry where, as was
noted here, moirés naturally occurs. For those prepress houses, contone
proofs are not an option, unfortunately.
BTW, I was told that stochastic printing completely eliminates any possible
moiré. Can anybody confirm that there is any truth to this?
Roger
Unless a dot proof is made from exactly the same engine that is used to
make
the final plates, its usefulness is very limited, and the simulation
very
approximate. If not done this way, you're not going to see the exact
same
dot structure that is ending up on press and whether or not it may
generate
unwanted effects like moiré.
As for appearance, which is what most of us this side of platemaking
are
interested in, contone proofs are more than sufficient to predict the
visual
results on the final printed sheet.
Marco Ugolini
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden