HP 4850C is supported by sane and is also recognised by scanimage -h.
Scanning using the usual apps (scanimage, xsane, LibreOffice) does work,
but the resulting image is all black (yes, there is a document to scan under
the hood! :-).
How to fix this problem?
It is listed in /etc/sane.d/genesys.conf:
# Hewlett Packard ScanJet 4850C
usb 0x03f0 0x1b05
and, as said: all scan apps, incl. sane-find-scanner -v -v, do find it:
searching for USB scanners:
<device descriptor of 0x03f0/0x1b05 at 003:008 (Hewlett-Packard HP Scanjet
<trying to find out which USB chip is used>
<This USB chip looks like a GL646_HP (result from sane-backends 1.0.24)>
found USB scanner (vendor=0x03f0 [Hewlett-Packard], product=0x1b05 [HP Scanjet
Scanner], chip=GL646_HP) at libusb:003:008
(FYI: I've to start WinXP in VirtualBox and there LibreOffice to get scanning
with this scanner working. But I want to get rid of Windows; this is the
only remaining thing that isn't working for me yet under Linux).
OS: Debian 8 x86_64 w/stock kernel and the following *sane* related packages:
# dpkg -l | grep -i sane
ii libsane:amd64 1.0.24-8
ii libsane-common 1.0.24-8
ii libsane-extras:amd64 126.96.36.199
ii libsane-extras-common 188.8.131.52
ii sane-utils 1.0.24-8
ii xsane 0.998-6+b1
ii xsane-common 0.998-6