I have a Canon LiDE 120 scanner connected to a Ubuntu 16.4 box. The scanner is detected, but the produced images are completely black.
More precisely, if I press "scan" or "preview" in
xsane, there is a short initial noise from the scanner motor, then nothing is happening for about half a minute, then the scan is performed (lamp on) and the resulting image is black. Scanning from the command line with
scanimage, the behavior is exactly the same (including delay). The scanner does work on Windows, so the hardware should be fine. Using the Color picker tool in Gimp a few times, I checked that the color is totally black (all color values equal 0).
Maybe the delay for half a minute is somehow connected to the problem? (Could be some sort of a timeout)
The picture from searching for this problem is not completely clear: First, Sane support for the Canon LiDE 120 was problematic at least till 14.04. Apparently a few setups on 16.04 are running flawlessly, others seem to have the same problem. As a source of errors it was reported that the lock switch at the lower surface of the scanner has to be unlocked (this is the case, I also tried lock-unlock-restart) and USB ports behind an external USB hub (scanner is directly connected, I tried different USB ports).
Bus 001 Device 004: ID 04a9:190e Canon, Inc.
device `genesys:libusb:001:004' is a Canon LiDE 120 flatbed scanner