Re: filmscanners: Vuescan grain removal idea

["Rob Geraghty" <harper@wordweb.com>]

"Henry Richardson" <itai46@hotmail.com> wrote:
[snip]
> another story.  I often get grain aliasing in the sky but other areas of
the
> image rarely have much of a grain aliasing problem.  I'm not sure why this
> is so, but it has been my pretty consistent experience.  Even stranger,
even
> other highlight areas don't exhibit the problem.  It is mostly just the
sky
> -- blue, cloudy, or overcast doesn't matter.

I have the same issue, and it's much more of a problem in Vuescan than
Nikonscan.  I believe it's actually partly due to Vuescan doing its absolute
best to get every scrap of "data" out of the film.  Where Nikonscan would
allow the sky to get "blown out" slightly and lose the grain detail, Vuescan
retains it and makes it look darker.  You can adjust the levels in PS or
PSP a little to compensate, but then you have to rebalance the colours.
I found that using the clean function in Vuescan or ICE in Nikonscan
softens the image a little and reduces the harshness of the aliasing in the
sky, but it also affects the whole image.

> My guess is it takes a
> combination of a fairly light area plus some  amount of blue.

The greatest amount of noise seems to be in the blue channel.

> I wonder if Vuescan could have a grain removal option that would only work
> on the highlight areas of the image or something like that?  Reducing the
> ugly grain aliasing from the sky without softening the rest of the image
> might get a lot closer to solving the problem, as I see it.

I like this idea.  I would really like to be able to use grain removal on
the
sky without affecting the sharpness of the rest of the image.

The aliasing is less obvious in the rest of the image because the rest of
the
image generally isn't a large area of bright monochrome, particularly blue.
This whole issue with scanning has turned me around from taking neg film
and back to slides, because I can get far better scans out of *any* slide
film than print film.  Wish I could always afford to shoot Provia 100F. :)

Rob