.TH sane-canon 5 "29 May 2001"
.IX sane-canon
.SH NAME
sane-canon - SANE backend for Canon flatbed scanners
.SH DESCRIPTION
The
.B sane-canon
library implements a SANE (Scanner Access Now Easy) backend that
provides access to the following Canon flatbed scanners:
.PP
.RS
CanoScan 300
.br
CanoScan 600
.br
CanoScan 2700F                                                          
.br
.RE
.PP
No parallel port and USB scanners are supported and there are no plans to
support them in the future.
.PP
IMPORTANT: this is alpha code. Don't expect this to work
correctly. Many functions are missing, others contain errors. In some
cases, your computer might even hang. It cannot be excluded (although
I consider it extremely unprobable) that your scanner will be
damaged.
.PP
That said, TESTERS ARE WELCOME. Send your bug reports and comments to
Manuel Panea <mpd@rzg.mpg.de>.
.PP
.SH "DEVICE NAMES"
This backend expects device names of the form:
.PP
.RS
.I special
.RE
.PP
Where
.I special
is the path-name for the special device that corresponds to a
SCSI scanner. The special device name must be a generic SCSI device or a
symlink to such a device.  The program 
.IR sane-find-scanner 
helps to find out the correct device. Under Linux, such a device name
could be
.I /dev/sga
or
.IR /dev/sge ,
for example.  See sane-scsi(5) for details.

.SH CONFIGURATION
The contents of the
.I canon.conf
file is a list of device names that correspond to Canon
scanners.  Empty lines and lines starting with a hash mark (#) are
ignored.  Only one device name can be listed in 
.IR canon.conf .

.SH TIPS
.PP
When scanning either slides or negatives, I found that I must set the
gamma value to something about 2.2 to 2.4 (I set the same value for all
three red, green, blue). Also, for slides, using "Auto Exposure" helps
a lot.
.PP
The "Auto Exposure" function for slides makes the scanner do a first
pass on the film to determine the Highlight and Shadow point
values. The "Auto Focus" function triggers yet another pass to
determine the focus value. After that, the real scanning pass takes
place. The "Auto Exposure" function is not available for negatives yet.
.PP
Even after "Auto Focus", the image I get is often a bit too
blurred. I found that using the GIMP to do a
"Filter->Enhance->Sharpen" at about 40 to 60 improves the image
quite a bit. In fact, I find it so good that I might implement a
sharpen filter into the backend in the future.                                
.PP
The "native" scanner resolutions of the 2700F are the integer
sub-multiples of 2720 dpi, i.e. 1360, 680, 340 and 170. You can scan
at any other resolution, but you will notice that the image has
noticeably more jaggies that when using one of the "native"
resolutions.                                                                  
.PP
.SH FILES
.TP
.I @CONFIGDIR@/canon.conf
The backend configuration file (see also description of
.B SANE_CONFIG_DIR
below).
.TP
.I @LIBDIR@/libsane-canon.a
The static library implementing this backend.
.TP
.I @LIBDIR@/libsane-canon.so
The shared library implementing this backend (present on systems that
support dynamic loading).
.SH ENVIRONMENT
.TP
.B 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 @CONFIGDIR@.  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
.B SANE_CONFIG_DIR
to "/tmp/config:" would result in directories "tmp/config", ".", and
"@CONFIGDIR@" being searched (in this order).
.TP
.B SANE_DEBUG_CANON
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=4

.SH "SEE ALSO"
sane(7), sane\-scsi(5), sane\-find\-scanner(1)
.br
http://www.rzg.mpg.de/~mpd/sane/
.br
@DOCDIR@/canon/canon.install2700F.txt (installation of a CanoScan 2700F)
.br
.SH AUTHOR
Helmut Koeberle, Manuel Panea, and Markus Mertinat
.br
Man page by Henning Meier-Geinitz (mostly based on canon.README)