Ubuntu Manpage: sane-canon_pp - SANE backend for Canon CanoScan Parallel Port flatbed scanners

NAME

       sane-canon_pp - SANE backend for Canon CanoScan Parallel Port flatbed scanners

DESCRIPTION

       The  sane-canon_pp  library  implements  a  SANE  (Scanner  Access  Now Easy) backend that
       provides access to the following Canon flatbed scanners:

              CanoScan FB320P
              CanoScan FB620P
              CanoScan FB330P
              CanoScan FB630P
              CanoScan N340P
              CanoScan N640P
              CanoScan N640P ex

       No USB scanners are supported and there are no plans to support them in the future.  Other
       projects  are  working on support for USB scanners. See the PROJECTS file for more detail.
       The FB310P and FB610P are re-badged Avision scanners which use a different command set, so
       are unlikely to be supported by this backend in the future.

       IMPORTANT:  this  is alpha code. While we have made every effort to make it as reliable as
       possible, it will not always work as expected.  Feedback  is  still  appreciated.   Please
       send  any  bug  reports  to  the maintainers as listed on the web page (listed in SEE ALSO
       below).

DEVICE NAMES

       This backend expects device names of the form presented by  libieee1284(3).   These  names
       are highly dependent on operating system and version.

       On  Linux  2.4 kernels this will be of the form parport0 or older (2.2 and before) kernels
       may produce names like 0x378 (the base address of your port) or simply 0 depending on your
       module  configuration.   Check  the  contents of /proc/parport if it exists.  If you don't
       want to specify a default port (or don't know its name), the backend  should  be  able  to
       detect which port your scanner is on.

CONFIGURATION

The contents of the canon_pp.conf file is a list of options for the driver to use. Empty
lines and lines starting with a hash mark (#) are ignored.

The supported options are currently ieee1284, calibrate, init_mode, and force_nibble

Option ieee1284 port-name defines which port to use. The format of port-name is OS
dependent, based on the names presented by libieee1284. Please only have one of these
lines, or all but one will be ignored.

Option calibrate cal-file [port-name] defines which calibration file to use on a per-port
basis. If you only have one parport, the port-name argument may be omitted - but be
careful as this will cause problems on multi-scanner systems. You may have as many of
these lines as you like, as long as each has a unique port name. The tilde (`~')
character is acceptable and will be expanded to the value of the HOME environment.

Option init_mode <AUTO|FB620P|FB630P> [portname] defines which initialisation (wake-up)
mode to use on a per-port basis. If you only have one parport, the portname argument may
be omitted - but be careful as this may cause problems on multi-scanner systems. You may
have as many of these lines as you like, as long as each has a unique port name. The
valid initialisation modes are FB620P (which strobes 10101010 and 01010101 on the data
pins), FB630P (which strobes 11001100 and 00110011 on the data pins) and AUTO, which will
try FB630P mode first then FB620P mode second. The FB620P mode is also used by the
FB320P. The FB630P mode is used by the FB330P, N340P, and N640P.

Option force_nibble forces the driver to use nibble mode even if ECP mode is reported to
work by libieee1284. This works-around the rare issue of ECP mode being reported to work
by the library, then not working.

TIPS

       Hit the "Calibrate" button before scanning.  It vastly improves the quality of scans.

       To  enable  automatic  detection  of  your  scanner,  uncomment  the  "canon_pp" line from
       /etc/sane.d/dll.conf

FILES

       /etc/sane.d/canon_pp.conf
              The backend configuration file (see also description of SANE_CONFIG_DIR below).

       /usr/lib/x86_64-linux-gnu/sane/libsane-canon_pp.a
              The static library implementing this backend.

       /usr/lib/x86_64-linux-gnu/sane/libsane-canon_pp.so
              The shared library implementing this  backend  (present  on  systems  that  support
              dynamic loading).

ENVIRONMENT

       SANE_CONFIG_DIR
              This  environment  variable  specifies the list of directories that may contain the
              configuration file.  On *NIX systems, the directories  are  separated  by  a  colon
              (`:'),  under  OS/2, they are separated by a semi-colon (`;').  If this variable is
              not set, the configuration file is searched in two default directories: first,  the
              current  working  directory  (".")  and  then  in /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 /etc/sane.d being searched (in this order).

       SANE_DEBUG_CANON_PP
              If  the  library was compiled with debug support enabled, this environment variable
              controls the debug level for  this  backend.   Higher  debug  levels  increase  the
              verbosity of the output.

              Example: export SANE_DEBUG_CANON_PP=4

NOTES

Features available in the Windows interface

Brightness and Contrast
These are not implemented, and probably never will be. These appear to be
implemented entirely in software. Use GIMP or a similar program if you need these
features.

Descreen Mode
This appears on our first analysis to be just oversampling with an anti-aliasing
filter. Again, it seems to be implemented entirely in software, so GIMP is your
best bet for now.

Gamma Tables
This is under investigation, but for now only a simple gamma profile (ie: the one
returned during calibration) will be loaded.

Communication Problems

ECP mode in libieee1284 doesn't always work properly, even with new hardware. We believe
that this is a ppdev problem. If you change the configuration file to include
force_nibble , the problem will go away, but you will only be able to scan in nibble mode.

Sometimes the scanner can be left in a state where our code cannot revive it. If the
backend reports no scanner present, try unplugging the power and plugging it back in.
Also try unplugging printers from the pass-through port.

The scanner will not respond correctly to our commands when you first plug in the power.
You may find if you try a scan very soon after plugging in the power that the backend will
incorrectly report that you have no scanner present. To avoid this, give it about 10
seconds to reset itself before attempting any scans.

Repeated Lines

Sometimes at high resolutions (ie. 600dpi) you will notice lines which appear twice.
These lines correspond to points where the scanner head has stopped during the scan (it
stops every time the internal 64kb buffer is full). Basically it's a mechanical problem
inside the scanner, that the tolerance of movement for a start/stop event is greater than
1/600 inches. I've never tried the windows driver so I'm not sure how (or if) it works
around this problem, but as we don't know how to rewind the scanner head to do these bits
again, there's currently no nice way to deal with the problem.

Grey-scale Scans

Be aware that the scanner uses the green LEDs to read grey-scale scans, meaning green
coloured things will appear lighter than normal, and red and blue coloured items will
appear darker than normal. For high-accuracy grey-scale scans of colour items, it's best
just to scan in colour and convert to grey-scale in graphics software such as the GIMP.

FB620P/FB320P Caveats

These models can not be reset in the same way as the others. The windows driver doesn't
know how to reset them either - when left with an inconsistent scanner, it will start
scanning half way down the page!

Aborting is known to work correctly on the FB*30P models, and is known to be broken on the
FB*20P models. The FB620P which I tested on simply returns garbage after a scan has been
aborted using the method we know. Aborting is able to leave the scanner in a state where
it can be shut down, but not where another scan can be made.

AUTHOR

       This backend is primarily the work of Simon Krix (Reverse Engineering), and Matthew Duggan
       (SANE interface).

       Many thanks to Kevin Easton for his comments and help, and Kent A. Signorini for his  help
       with the N340P.

                                           11 Jul 2008                           sane-canon_pp(5)