[sane-devel] Why is the background of the scanned image not a constant grayscale
Martijn van Oosterhout
Martijn van Oosterhout <kleptog@svana.org>
Wed, 14 May 2003 10:06:18 +1000
--mYCpIKhGyMATD0i+
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable
On Tue, May 13, 2003 at 11:31:17AM -0500, Peter Chen wrote:
> Hi,
>=20
> I still do not quite understand. When I tried to scan the same image using
> Twain, there was no gray background. What could be the reason?
>=20
> And I could not find the option to set the option brightness/contrast whe=
n I
> ran: scanimage --help -d fujitsu:/dev/usb/scanner0.
Perhaps you need to do some calibration? The HP5400 scanner has a white
strip inside the scanner which you scan first. That gives the white level
for each colour and pixel. That's then used to fix up the rest of the
image.
--=20
Martijn van Oosterhout <kleptog@svana.org> http://svana.org/kleptog/
> "the West won the world not by the superiority of its ideas or values or
> religion but rather by its superiority in applying organized violence.
> Westerners often forget this fact, non-Westerners never do."
> - Samuel P. Huntington
--mYCpIKhGyMATD0i+
Content-Type: application/pgp-signature
Content-Disposition: inline
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.0.6 (GNU/Linux)
Comment: For info see http://www.gnupg.org
iD8DBQE+wYh5Y5Twig3Ge+YRAs5eAKCFd7ZxyT+HPN6yixzngTyjjntAowCfQP48
3ex7ceiU1/QBljd0vT538JA=
=M81q
-----END PGP SIGNATURE-----
--mYCpIKhGyMATD0i+--