sane-canon_pp - SANE backend for Canon CanoScan Parallel Port flatbed scanners
library implements a SANE (Scanner Access Now Easy)
backend that provides access to the following Canon flatbed scanners:
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
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
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.
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
The supported options are currently ieee1284
, 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]
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,
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.
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
- The backend configuration file (see also description of
- The static library implementing this backend.
- The shared library implementing this backend (present on
systems that support dynamic loading).
- 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).
Features available in the Windows interface
- 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
- 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
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
, 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.
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.
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.
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.
sane(7), sane-dll(5) http://canon-fb330p.sourceforge.net/
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.