sane-mustek expects device names of the form:
special
where special is the path-name for the special device that corresponds to a SCSI scanner. For SCSI scanners, the special device name must be a generic SCSI device or a symbolic link to such a device.
mustek.conf contains a list of options and device names that correspond to Mustek scanners. Empty lines and lines starting with a hash (``#'') are ignored.
The three options supported are linedistance-fix, lineart-fix, and strip-height. There are two types of options: global and positional. Global options apply to all devices managed by the backend whereas positional options apply just to the most recently mentioned device. This means that the order in which the options appear is important. linedistance-fix is positional and works around a problem that occurs with some SCSI controllers. If color scans have horizontal stripes and the colors are in black and white, then it is likely that your controller suffers from this problem. Turning on this option usually fixes the problem.
lineart-fix is positional and works around a timing problem that seems to exist with certain MFS-12000SP scanners. The problem manifests itself in dropped lines when scanning in Line Art mode. Turning on this option should fix the problem but may slow down scanning.
strip-height is a global option that limits the maximum height of the strip scanned with a single SCSI read command. The height is specified in inches and may contain a fractional part (for example, 1.5). Setting the strip-height to a small value (one inch, for example) reduces the likelihood of encountering problems with SCSI driver timeouts and timeouts with other devices on the same SCSI bus. Unfortunately, it also increases scan times. Thus, if the scanner is the only device on the SCSI bus it is connected to and if it is known that the SCSI driver does not suffer from premature timeouts, it is recommended to increase the strip-height or remove the option completely, which corresponds to an infinite strip height.
A sample configuration file is shown below:
# limit strip height of /dev/scanner to 1.5 inches: option strip-height 1.5/dev/scanner # first Mustek scanner
/dev/sge # second Mustek scanner option linedistance-fix
The SANE_CONFIG_DIR environment variable specifies the list of directories that may contain the configuration file. The directories are separated by a colon (``:''). If this variable is not set, the configuration file is searched in two default directories: firstly, the current working directory (``.'') and then in /usr/local/etc/sane.d. If the value of the environment variable ends with the directory separator character, then the default directories are searched after the explicitly specified directories. For example, setting SANE_CONFIG_DIR to ``/tmp/config:'' would result in directories tmp/config, ``.'', and /usr/local/etc/sane.d being searched (in this order).
SANE_DEBUG_MUSTEK environment variable controls the debug level for sane-mustek, if the library was compiled with debug support enabled. For example, a value of 128 requests all debug output to be printed. Smaller levels reduce verbosity.
If you already have a working SCSI controller in your system, you should consider that Mustek scanners do not support the SCSI-2 disconnect/reconnect protocol and hence tie up the SCSI bus while a scan is in progress. This means that no other SCSI device on the same bus can be accessed while a scan is in progress.
Because the Mustek-supplied adapter is not interrupt driven and because Mustek scanners do not support the SCSI-2 disconnect/reconnect protocol, it is recommended to install a separate SCSI controller for Mustek scanners (for example, ncr810 based cards).
For Mustek scanners, it is typically necessary to configure the low-level SCSI driver to disable synchronous transfers, tagged command queuing, and target disconnects.
The ScanExpress models sometimes have trouble with high resolution color mode. If you encounter sporadic corrupted images (parts duplicated or shifted horizontally), kill all other applications before scanning and (if sufficient memory available) disable swapping.
After a while of no activity, some scanners (not the SANE backend) turn off their CCFL lamps. This shutdown is not always perfect with the result that the lamp sometimes continues to glow dimly at one end. This does not appear to be dangerous since as soon as you use the scanner again, the lamp turns back on to the normal high brightness. However, the first image scanned after such a shutdown may have stripes and appear to be over-exposed. When this happens, take another scan to get a good image.
Transparency adapter and automatic document feeder support is lacking.
There is a performance problem that makes scanning on three-pass scanners slower than necessary. High resolution with ScanExpress scanners is slow as they have a very small internal buffer.
Authors are David Mosberger, Andreas Czechanowski and Andreas Bolsch.