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

ieee1284 port-name
Defines which port to use. The format of port-name is OS dependent, based on the names presented
by libieee1284(3). Please only have one of these lines, or all but one will be ignored.

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
variable.

init_mode <AUTO|FB620P|FB630P> [port-name]
Defines which initialisation (wake-up) mode 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 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.

force_nibble
Forces the driver to use nibble mode even if ECP mode is reported to work by libieee1284(3). 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(3) 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)