# Re: SANE & exposure times

Ewald R. de Wit (ewald@pobox.com)
Sat, 31 Jul 1999 11:01:40 +0200

- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
- Next message: Ewald R. de Wit: "Re: SANE & exposure times"
- Previous message: Stephen Williams: "Re: SANE & exposure times"
- In reply to: Andreas Rick: "Re: SANE & exposure times"
- Next in thread: Oliver Rauch: "Re: SANE & exposure times"

Andreas Rick (rickand@gemse.fr) wrote:
> I think you are right: When scanning negatives with the Coolscan scanners
> the backend tells the scanner it is doing a negatives and the
> scanner adapts its exposure range to the right levels for negatives.
> That's why you don't get the same image when scanning a negative
> using "positive" as a backend-option and inverting the image yourself.
> I havn't tested the quality of this exposure adaptation throughout
> a significant image base of negatives yet, but I didn't have any problems with
> it either.

Okay, so the coolscan scanner apapts the exposure automatically. That
is cool but I would still like to know the exact exposure ratios. The
current situation when scanning negatives is that you have to fiddle
with gamma sliders till you get some slightly credible color balance.
And that for every negative. This is time consuming and highly non-optimal.

> Perhabs this is different for the HP-Photosmart?

The Photosmart doesn't adapt exposures automatically but the theory
is the same of course.
> So without doing multiple scanning there is no way of getting more
> than 8-Bit out of the LS-20, 10 bit out of the LS-30 or 12 bit out of the
> LS-2000 and there doesn't seem to be much neccessity to change
> exposure values to get these 8/10/12 bit.
> Can the other users of these Scanners confirm this hypothesis?

I think the Nikons are quite unique in that they fill up the bitrange
automatically but I'm not sure.
> I don't know too much about the subject, but I think there must be
> some standards allready defined that we can use.
> Who does know more about this.

You might like to read the color and the gamma FAQ at
http://www.inforamp.net/~poynton/Poynton-color.html

    --
      --  Ewald

    --
    Source code, list archive, and docs: http://www.mostang.com/sane/
    To unsubscribe: echo unsubscribe sane-devel | mail majordomo@mostang.com

     Next message: Ewald R. de Wit: "Re: SANE & exposure times"
     Previous message: Stephen Williams: "Re: SANE & exposure times"
     In reply to: Andreas Rick: "Re: SANE & exposure times"

     Next in thread: Oliver Rauch: "Re: SANE & exposure times"