filmscanners: Merging multiple scans in Photoshop to deal with very high-contrast scenes

["Jawed Ashraf" <Jawed@cupidity.force9.co.uk>]

[Digging back in time here...: I know the following isn't really a direct
answer to the question, but I just thought I'd bring this technique to your
attention]

Using this:

http://www.digitalsecrets.net/secrets/DynamicRanger.html

as the basis for the technique, me and Joel Benford (lurker on this list)
set about merging 3 frames into 1 image.  We did this on a number of images.
He'd used a tripod to make night photographs and carefully bracketed, with
the intention of merging later.

His HP Photosmart S20+ scanner is no good for this task, as the motorised
film feed during scanning causes misregistration of the images.  So we
ended-up using my Primefilm 1800 scanner (you may think this scanner is crap
but it has pixel perfect registration, something I still find quite
astonishing!).  I no longer have the Primefilm.  Tests with the LS40 show it
does the job equally well.

Instead of using Peter's four control points for the +2EV image, I used two:

        255     85
        127     70

And instead of using his control points for the -2EV image, I used:

        0       172
        127     195


The results were very worthwhile.  See some samples at:

http://www.photo.net/photodb/photo?photo_id=240571
http://www.photo.net/photodb/photo?photo_id=268265

The hardest part is correcting for any rotational error you introduce by
scanning.  You should experiment with the curves, to suit your taste and, I
suppose, the nature of the film used.

Of course, Vuescan does this automatically for a single frame, if your
scanner supports Vuescans "long exposure pass" option.

Jawed


> -----Original Message-----
> From: owner-filmscanners@halftone.co.uk
> [mailto:owner-filmscanners@halftone.co.uk]On Behalf Of Rob Geraghty
> Sent: 26 September 2001 00:10
> To: filmscanners@halftone.co.uk
> Subject: filmscanners: RE: filmscanners: Merging multiple scans in
> Photoshop to deal with very high-contrast scenes
>
>
> Anthony asked:
> >Has anyone here done any significant work with merging multiple scans to
> >overcome limitations of film in high-contrast scenes?
>
> I've tried it with two layers.  It tends to show up the limitations of the
> scanner very quickly.  If you have a scanner with a good range, you may
> not have the same issues I did with the LS30.  The balance
> between the layers
> had to be very carefully made, or dark noise and banding ruins the image.
>
> Rob
>
>
> Rob Geraghty harper@wordweb.com
> http://wordweb.com
>
>
>
>