Epson Perfection V700 scanner

One of the hottest scanner, Epson Perfection V700 is tested for usable
density range.

Manufacturers always hype about the maximum readable density. So I
have tested my scanner for this spec using a calibrated density wedge
and custom software. Above the optical density (OD) of 1, the sensor's
sensitivity declines gradually. By OD of about 2.4, the sensitivity
has gone down to about half the maximum value (at OD below 1). This
scanner is usable for normal negative density range, but it would not
be a good choice for extremely dense films, if information in dense
area (OD > 2.0) is important.

Method: Stouffer TP35C was scanned by V700 and Vuescan 8.3.52 on Mac
OS 10.4.7 with 16 pass and 300dpi. CCD raw signal was saved in
grayscale 16 bit mode for analysis. Using a custom MATLAB program,
reading values (ordinate) were obtained for eacy density value
(abscissa) by averaging a sufficiently large area in each patch to
reduce the effect of scanner noise and granularity. The actual
calibrated density values provided by Stouffer are used for the
abscissa.

I have the plot of density v. CCD value in PDF format, downloadable
from the bottom of this page:

http://wiki.silvergrain.org/wiki/index.php/Perfection_V700

Although the result wasn't as good as I hoped, and it was of course
far worse than what manufacturer prints in their catalogues, I'd say
it's pretty decent for usual negative scanning work.

Note that I used 300dpi at 16 pass, and averaged a lot of pixels. This
is to reduce the measurement noise. With a higher resolution and
individual pixel values, the scanner won't be able to resolve high
densities as shown in my plot, because the noise will rise. (That is,
the performance shown by my plot is the best ability and in reality
this should be very conservatively applied. I thought about adding
errorbars to indicate this point, but then I didn't want to bother.)

Also, what this means is that, the scanner may be used as a
densitometer only for density below 1.0, if custom calibration is not
performed to compensate for the declining contrast in density above 1.
With such custom calibration, the scanner is probably very usable up
to 2, or perhaps even 2.4, if low res, multi-pass scan and a lot of
pixel averaging are used.
Received on 07/07/06-02:00:13 AM Z