Re: scanner density-value relation

----- Original Message -----
From: "Ryuji Suzuki" <rs@AgX.st>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Wednesday, March 09, 2005 12:58 AM
Subject: Re: scanner density-value relation

> From: Richard Knoppow <dickburk@ix.netcom.com>
> Subject: Re: scanner density-value relation
> Date: Wed, 09 Mar 2005 00:45:52 -0800
>
>> For that matter reasonable measurements of density can be
>> made
>> visually by comparison to known neutral density filters.
>
> You can put the negative exposed by a step tablet and the
> step tablet
> on the unexposed blank area nearby the exposed area,
> together on a
> light table and guestimate the average gradient by
> eyeballing. The
> judgement error (in terms of psychophysical difference
> limen or just
> noticeable difference) depends on the size of the patch
> and the
> transmitted irradiance among various factors. But using a
> scanner is
> preferable because experimental data are recorded in the
> form of raw
> TIFF file which can be reanalyzed if the data is
> questioned later.
>
> --
> Ryuji Suzuki
  Well, the scanner is preferable because it doesn't rely on
the eye and interpretation. However, if one _must_ make do,
the visual method will at least get you in the ball park.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com