RE: Densitometer/Spectrophotometer to read printed sheets
RE: Densitometer/Spectrophotometer to read printed sheets
- Subject: RE: Densitometer/Spectrophotometer to read printed sheets
- From: Ray Maxwell <email@hidden>
- Date: Wed, 3 Jul 2002 15:06:06 -0700
Hi Ray,
I am not sure what your are trying to do exactly, but your question brings
up some good points on measuring instruments.
1. A spectodensitometer will measure dot area for each CMY color. The K
reading will include CMY and K. However, this reading will include both
mechanical dot gain and optical dot gain. The dot area measured will not
equal the original tone specified in an application like Illustrator.
This type of measurement is very good at keeping a single printing process
controlled. Dot area measurement is not an accurate way to match color when
trying to match a proofing and a printing process. The filters used, do not
match the typical response of the human eye. They are chosen to match the
typical printing pigments.
2. A Scanning dot meter like the Ultra Dottie will measure the actual dot
area on the press sheet which will include mechanical dot gain. It
eliminates most of the optical dot gain. Again this is not the same as the
original value specified in an application like Illustrator.
This type of measurement is very good for monitoring the process control of
plates. Once again, this type of measurement does not reflect the response
of the human eye with regard to color.
3. CIELab measurement actually uses a model of human perception to tell you
what the color response of a typical human will be.
This type of measurement is not perfect, but gives a good way to match
different types of printing systems.
If you could clear up exactly what you are trying to do, I can give you more
information.
Ray
Ray Maxwell
Senior Color Systems Engineer, Inkjet Printing
Creo Inc.
4225 Kincaid Street
Burnaby, B.C.
Canada V5G 4P5
Phone (604) 451-2700 ext. 2004
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From: Ray Landis
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Reply To: email@hidden
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Sent: Wednesday, July 3, 2002 5:11 AM
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To: 'email@hidden'
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Subject: Densitometer/Spectrophotometer to read printed sheets
>
>
Hello,
>
>
Is anyone aware of a measuring device that can determine dot percentage
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per
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color from a CMYK Process printed sheet? There is a product from Beta
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called the Ultra Dottie whose online documentation leads one to believe
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that it can. Has anyone used it?
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We basically want to use it to assist in correcting scans from pre-printed
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copy.
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Thanks,
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Ray Landis
>
Techbooks
>
email@hidden
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