[sane-devel] xsane-0.87 released

Oliver Rauch oliver.rauch@rauch-domain.de
Tue, 16 Jul 2002 18:07:31 +0200

Henning Meier-Geinitz schrieb:
> Hi,
> On Mon, Jul 15, 2002 at 06:09:28PM +0200, Oliver Rauch wrote:
> > I do not understand how a backend can make available a
> > contrast and brightness option in lineart mode but no
> > threshold option.
> The mustek backend provides brightness and for some scanners also
> contrast, the mustek_usb backend has only brightness for lineart mode.
> I guess it's because the Windows drivers also use these option names.
> Does it make sense to change the brightness option to threshold for
> lineart mode? Is "threshold" used for lineart in most other backends?

Hello Henning,

a threshold value is something that is clear to me.
a brightness value can be implemented in a comparable way to a threshold value.
but what makes a contrast value for a lineart image?
The contrast is defined by the two colors that are used: black and white.
I do not understand what the contrast value does change.

grep  -i threshold *.c | cut -d: -f1 | sort -u | wc -l
show that 32 backends have the text "threshold" included.
We have about 50 backends defined.

We will have to make it common one day. If you like to change it in the
mustek backends then the users will have the advantage that they can do
a preview scan in grayscale mode with xsane and they can change the
threshold without doing a new scan.


Homepage:	http://www.rauch-domain.de
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