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.
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/sane/libsane-canon_pp.a
The static library implementing this backend.
/usr/lib/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. Under UNIX, 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.
SEE ALSO
sane(7), sane-dll(5) http://canon-fb330p.sourceforge.net/
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)