[sane-devel] Scanning produces black images

[JKD]

El Sun, 15 de Apr de 2007, a las 09:58:08PM +0200, Magnus Rosenbaum dijo:
> I upgraded my Linux kernel from 2.6.18 to 2.6.19 and noticed a strange
> behaviour in xsane and also in kooka: The program acts als it would
> normally scan, but the scanner does not do anything and the result is a
> completely black image.
> 
> However scanning with scanimage works allright!
> 
> The behaviour is reproducible with kernel 2.6.19 and also 2.6.21-rc5. When
> I boot 2.6.18 scanning works as expected again.
> 
> Does anyone have an idea, how I could further investigate this problem?

Some days ago a user reported the same issue. For some unknown reason,
with newer kernels some backends are experiencing problems, retrieving a
black image from scanner. This is my experience about this issue with
hp3900 backend:

I've installed ubuntu 7.04 beta in vmware (kernel 2.6.20-15-generic) and
updated 329 packages.

SANE packages (including libsane-extras) are installed by default
libsane          1.0.18-3ubuntu1
libsane-extras   1.0.18-5
sane-utils       1.0.18-3ubuntu1
xsane            0.99+0.991-1ubuntu2
xsane-common     0.99+0.991-1ubuntu2

When I try to scan from xsane, a black image is retrieved. Enabling
debugging messages I see that reading bulk transfers return zeroes.

In my case, hp3900 backend is still an external backend included in
libsane-extras. So I removed libsane-extras package and installed the
current version of hp3900, compiled in kernel 2.6.20 and located at:

https://sourceforge.net/project/showfiles.php?group_id=150599

file: hp3900-sane_debian_bin_0.8-1_i386.deb

Once installed, xsane works fine as root. There is an issue in this
package with permisions so scanning is possible only as root until a new
release (soon).

I don't really know what the real problem is. Perhaps backends must be
compiled against current library or kernel versions. Once compiled,
problem is fixed.

Jonathan Bravo Lopez