# Re: [long] Overall usage impressions

John Labovitz (johnl@meer.net)
Mon, 25 May 1998 23:14:49 -0700

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Paul D. Robertson <proberts@clark.net> wrote:

> On Mon, 25 May 1998, Andreas Tille wrote:
>
> > I think we could implement such a feature if someone who found out some
> > good Gamma corrections for his favourite films would send them to the
> > development team so that they can collect values vor different films.
> > This would enhance the usability of slidescanners (slide extensions at
> > flat scanners).
>
> I think this is a more difficult task than it first seems. Ideally,
> you'd have to figure out a good "test target" to take a picture of, then
> balance each color intensity to that of the target given the same
> exposure conditions for each film.

Perhaps there's some way to `benchmark' for different films -- for
instance, if there was a standard grayscale (or Zone) test pattern
that I could shoot using my camera, then develop the film, then run
that test image through xscanimage... just an idea. I know far less
about how one would do that for color film.

> [...] I'd think that
> saving and restoring intensity values by name would be an interesting
> start, then someone would only need to maintain a master file of common
> names and values for the "Restore settings" menu selection.

It would also be nice to store scan mode (grayscale/color) and
negative/positive in a particular film profile.

Just to throw a sample out there -- my best (so far) setting for
scanning Kodak Tri-X Pan 320 B&W negatives (also seems to work ok for
Kodan T400CN) is about (0.8,2.0), meaning that I use the straight-line
tool, add a curve point, and move it to the right 0.8 of the left-most
cell, and upwards 2 cells from the bottom. (I can't seem to get good
results if I just type in a gamma number.)

john

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