Dot proofers
Dot proofers
- Subject: Dot proofers
- From: Mark Rice <email@hidden>
- Date: Sun, 5 Mar 2006 12:31:41 -0500
If you have an inkjet device that prints at 600 or 1200 dpi, and you
are attempting to simulate dots that would appear on a 4000 dpi
platesetter, there is no way you will achieve the same dot structure,
or even the same screen angles.
Several years ago I worked with someone who was an excellent
postscript programmer. He designed an algorithm that would feed in
screen angles at 1 degree intervals, and then see what came out of
the image setter (1200 dpi).
Here are some of the input angles and actual achieved output angles:
In Out
1 .8
2 1.7
3 2.5
4 3.3
5 4.2
6 4.9
7 5.7
8 9.3
9 9.9
and so on.
Because the device did not have enougth resolution to place the dots
in the appropriate xy coordinates to achieve the angles, a lot of
compromises had to be made. In addition, the low resolution meant the
exact dot shape could not be achieved.
So to me, these devices are worthless in terms of predicting moire.
They can be very good at predicting color.
Mark Rice
www.zero1inc.com
Several years
On Mar 3, 2006, at 6:07 PM, Graeme Gill wrote:
Mark Rice wrote:
I find that the various types of "dot-proofs" are extremely
deceptive. True,
in the past, the intent of proofing the dots was to predict moire.
However,
most new dot proof devices are postscript driven, and do not have
the same
resolution or dot forming engine of the CTP device the file will
end up on.
Therefore, they only provide a deceptive dot that DOES NOT predict
the
potential moire on the output device. The only proofing device I
know of
that give absolute dot prediction is the Creo Spectrum, which can
output
proofs and plates on the same device.
Maybe some are like that, but any serious dot proofer takes
imagesetter output, not PostScript, and reproduces the actual
dots, rather than inventing them.
Graeme Gill.
_______________________________________________
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