Re: Dot Gain
Re: Dot Gain
- Subject: Re: Dot Gain
- From: Roger Breton <email@hidden>
- Date: Tue, 29 Apr 2003 13:10:50 -0400
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Michael,
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Just to sure it has been said in this discussion. The measurement of dot
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gain is based on two factor. 1. The physical change in the dot size and 2.
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something called optical dot gain. That is how the eye sees the change of
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the dot based on how the dot is printed on paper. The combination of those
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to factors is what dot gain is based on. Of course this is all formulated
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into a equation that is built into a tool like a densitometer that measures
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percent dot area.
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A common communication mistake is to only look at the physical dot gain and
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then discuss the dot gain issue with someone who is thinking about dot gain
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that is calculated using both physical and optical dot gain measurements.
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This might be what is going on in your case. But then again you might only
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have a 10% dot gain.
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Jim Rich
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Jim,
A typical "dot area" reading on a densitometer does not separate
"mechanical" from "optical" gain : they're both taken into account by the
measurements. In fact, this difficult separation of the two can be
accomplished by the addition of an "N-factor" or by the use of a device
called a ScanDot. (please correct me if I am wrong or you want to include
more qualification of this process or the gist of the underlying
Yule-Neilson equation)
A ScanDot densitometer functions just like a scanner. It measures the
percentage of area covered by dots. But the Murray-Davies equation is only
based on density readings. In my view, density captures both mechanical and
optical dot gain. It is difficult to separate the two. In the end, I think
we all suffer from a "dot gain phobia", meaning we don't want any dot gain
or when there is, we would like t to be different or smaller or larger,
because we're so accustomed to se it one way or another. Personally, as long
as Murray-Davies is the way dot gain is calculated in Photoshop and all
other color-related or linearization function is concerned, I don't care.
That's a fact of life and I just deal with it. I make sure I read with a
proper instrument that conforms to Status T specifications.
Sorry if I err.
Roger Breton
Laval, Canada
email@hidden
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