Re: Dot Gain
Re: Dot Gain
- Subject: Re: Dot Gain
- From: "Peter Baumbach" <email@hidden>
- Date: Wed, 30 Apr 2003 15:29:46 +0200
Roger,
Roger wrote:
>
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)
I thought that the "optical" dot gain is something "only" perceived by the
visual system. Look at the so called Herman grid
(
http://www.michaelbach.de/ot/lum_scgrid/index.html). The white area between
the black dots is perceived as gray which would explain that the perceived
dot gain is larger than the measured dot gain. So I would say that a
densitometer just measures the amount of light which is reflected or
transmitted by the paper or film, in other words the "mechanical" dot gain
due to the actual distribution of ink on the paper or silver in the film.
The "N-factor" would then serve as a correction factor for the "optical" dot
gain and the logarithmic behaviour of the visual system when lightness is
involved.
Am I missing something?
Regards,
Peter Baumbach
email@hidden
www.pb-photo.net
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