RE: define linearization
RE: define linearization
- Subject: RE: define linearization
- From: Ray Maxwell <email@hidden>
- Date: Fri, 16 Aug 2002 16:35:22 -0700
Hi Greg,
In the days of film images setters it meant that you adjusted the system,
usually through software (using a Look Up Table), so that when you sent a
50% Postscript tint to the imagesetter you got 50% on film. Most people
checked this using 5% or 10% steps. You would output a step wedge...5%,
10%, 15%, 20%, etc. Then you would measure the results on film using a
densitometer and the Murry Davies equation. This was usually built into the
instrument such that it read out effective dot area or tonal value (more
modern term).
When this procedure is applied to proofers it usually means that you are
adjusting the device (using software and measuring instruments) to some
known stable condition. With most inkjets this means setting single channel
ink limits, calibrating the tone reproduction to have some standard dot gain
(TVI), and setting the total ink limits. The dot gain might be set to some
standard like SWOP (approx. 20%). It does not mean that the device in
linear in most cases. Usually the output at 50% would be 70% or 20% dot
gain or TVI (Tonal Value Increase).
The purpose is to get the unit into a know and stable condition that will be
easy to profile. If the device has very strange behavior, then it will be
difficult to profile accurately. In addition, it is quicker to do a
linearization than to do a new profile. So most people check the
linerarization on a regular basis so that they don't have to make a new
profile.
Linearization equals calibration. Profile equals characterization.
Ray
Creo
Ray Maxwell | Senior Color Systems Engineer, Inkjet Printing
4225 Kincaid Street | Phone (604) 451-2700 ext. 2004
Burnaby, B.C.
Canada V5G 4P5
IMAGINE CREATE BELIEVE
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From: email@hidden
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Sent: Friday, August 16, 2002 10:49 AM
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To: email@hidden
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Subject: define linearization
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Hi,
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In recent threads many have advised to linearize the output device, then
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calibrate, then profile.
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Anyone care to describe the linearize process further - specifically what
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the process involves, and what purpose it serves?
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Thanks!
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Greg
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