# Re: Fix for grayscale scans with gamma < 1.0

Oliver Rauch (oliver.rauch@Wolfsburg.DE)
Wed, 23 Jun 1999 21:54:16 +0200

- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
- Next message: Nick Lamb: "Re: Fix for grayscale scans with gamma < 1.0"
- Previous message: Oliver Rauch: "Re: Newbie question ;-)"
- Maybe in reply to: David Fox: "Fix for grayscale scans with gamma < 1.0"
- Next in thread: David Fox: "Re: Fix for grayscale scans with gamma < 1.0"
- Reply: David Fox: "Re: Fix for grayscale scans with gamma < 1.0"

David Fox wrote:

> Oliver Rauch <oliver.rauch@Wolfsburg.DE> writes:
>
> > David Fox wrote:
> >
> > > Oliver Rauch <oliver.rauch@Wolfsburg.DE> writes:
> > >
> > > > I uploaded xsane-0.26 to my homepage:
> > > > http://www.wolfsburg.de/~rauch/sane/sane-xsane.html
> > >
> > > Oliver,
> > >
> > > I've found a bug whose most obvious symptom is that grayscale scans
> > > with a gamma < 1.0 come out pure black.
> >
> > Hi David,
> >
> > thanks for that info,
> >
> > I thought I corrected all this
> > (but looks I only tested the color routines).
> >
> > This will be ok in xsane-0.27!
>
> No problem... I'm currently scanning some very old and deteriorating
> black and white photographs, and I've noticed a couple of problems
> with using xsane. First, the range of the xsane brightness and
> contrast controls is much less than the range provided in scanimage,
> at least with my HP-3c scanner using the HP back-end.
>
> Second, I think I will also need to be able to change the brightness
> and contrast settings used when acquiring the preview, and see new
> histograms and perform the usual xsane modifications in relation to
> those new ``default'' settings.

The birghtness and contrast of xsane is a software created digital gamma
table and has nothing to do with the options the scanner makes available,
these are still available in xsane under standard or advanced options!

You can change the scanner brightness and contrast and do a new preview
scan and see the changes in the histogram.
I think about adding support for a preview scan with more than 8/24 bits/pixel,
but I am not sure if that really is necessary.

>
>
> If we could make these changes (and I do plan to work on this) and add
> a few tweaks like changing the cursor when the rubber band is
> grabbable I think xsane could be a superior scanning client to any
> I've used in the Windows world. (IMHO.)
>

This is planned, but in the moment I spent my time for the umax backend
because UMAX gave me to scanners to test/make supported by the
backend.

May be next month I find the time to work again on xsane!

Bye
Oliver

    --
    EMAIL: Oliver.Rauch@Wolfsburg.DE
    WWW: http://www.wolfsburg.de/~rauch

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

     Next message: Nick Lamb: "Re: Fix for grayscale scans with gamma < 1.0"
     Previous message: Oliver Rauch: "Re: Newbie question ;-)"
     Maybe in reply to: David Fox: "Fix for grayscale scans with gamma < 1.0"

     Next in thread: David Fox: "Re: Fix for grayscale scans with gamma < 1.0"
     Reply: David Fox: "Re: Fix for grayscale scans with gamma < 1.0"