Re: [APML] scanner as densitometer

["westergren" <westergren@netzero.net>]

Dale,
I hope you can use your scanner as a densitometer.  I think I am using mine
that way.  I just completed and put on the web my film testing results where
I used my scanner (Epson 1640SU with transparency adapter) and read the
results of the negative images of RG&B LEDS with Photoshop 5.5 INFO command.

I made sure that the scanner control software was setting up the scanner to
exactly the same settings each time - not in any auto mode.  I tried using
Vuescan ,but couldn't find a pure manual setting mode.  I used the Epson
TWAIN driver software which did allow setting and saving the settings for
future use.

The Photoshop INFO command allows you to read the RGB values of a single
pixel, or to average over a 3x3 or 5x5 pixel area.  As long as your scan is
not saturated, it seems to be very sensitive and repeatable.  It won't give
you an absolute density, but it sure will tell the differences between your
three rolls of film.

To see my film test procedures and samples of my results go to:
http://home.nethere.net/mpd/TestProcedure/FilmTestProcedures.htm

Don

----- Original Message -----
From: "Dale Ireland" <direland@drdale.com>
To: "APML" <astro-photo@seds.org>
Sent: Wednesday, June 05, 2002 12:57 PM
Subject: [APML] scanner as densitometer


> hello
> I have some rolls of Royal Gold 200 that took a long trip to Australia and
> back, through airport security checked luggage, one through carry on
x-ray,
> one in a lead bag, and one little piggy stayed home. The film was
unexposed
> and after development there are some very slight differences that can be
> seen when the strips are laid out on a light table. I would like to
quantify
> the results and I am wondering if there is a way to use my Sprintscan 4000
> as a densitometer.
> If I take raw scan would the scanner's calibration routine overwhelm and
> confuse any differences in the essentially "clear" negatives or preserve
the
> very slight fogging so I could get a reading in Photoshop that would have
> any meaning? Any suggestions?
> Dale
>
>
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