sane-bh - SANE backend for Bell+Howell Copiscan II series document
scanners
DESCRIPTION
The
sane-bh
library implements a SANE (Scanner Access Now Easy) backend that
provides access to Bell+Howell Copiscan II series document
scanners. The Copiscan II 6338 has been the primary scanner model
used during development and testing, but since the programming interface
for the entire series is consistent the backend should work for the
following scanner models.
COPISCAN II 6338 Duplex Scanner with ACE
COPISCAN II 2135 Simplex Scanner
COPISCAN II 2137(A) Simplex Scanner (with ACE)
COPISCAN II 2138A Simplex Scanner with ACE
COPISCAN II 3238 Simplex Scanner
COPISCAN II 3338(A) Simplex Scanner (with ACE)
If you have a Bell+Howell scanner and are able to test it with this
backend, please contact
sane-devel@lists.alioth.debian.org
with the model number and testing results. Have a look at
http://www.sane-project.org/mailing-lists.html concerning subscription to
sane-devel. Additionally, the author is curious as to the likelihood of using
this backend with the newer 4000 and 8000 series scanners. If you have such a
beast, please let me know.
The Bell+Howell Copiscan II series document scanners are high
volume, high throughput scanners designed for document scanning
applications. As such, they are lineart/grayscale scanners supporting
a fixed number of fairly low resolutions (e.g. 200/240/300dpi).
However, they do have a number of interesting and useful features
suited to needs of document imaging applications.
This backend attempts to support as many of these features as possible.
The main technical reference used in writing this backend is the
Bell and Howell Copiscan II Remote SCSI Controller (RSC) OEM Technical Manual Version 1.5.
The Linux SCSI programming HOWTO, the SANE API documentation, and
SANE source code were also extremely valuable resources.
The latest backend release, additional information and helpful hints
are available from the backend homepage:
Where
special
is the path-name for the special device that corresponds to a SCSI
scanner. For SCSI scanners, the special device name must be a generic
SCSI device or a symlink to such a device. Under Linux, such a device
name takes a format such as
/dev/sga
or
/dev/sg0,
for example. See sane-scsi(5) for details.
CONFIGURATION
The contents of the
bh.conf
file is a list of device names that correspond to Bell+Howell
scanners. See sane-scsi(5) on details of what constitutes a valid device name.
Additionally, options can be specified; these lines begin with the word "option".
Each option is described in detail below. Empty lines and lines starting
with a hash mark (#) are ignored.
OPTIONS
The following options can be specified in the
bh.conf
file.
disable-optional-frames
This option prevents the backend from sending any optional frames. This
option may be useful when dealing with frontends which do not support these
optional frames. When this option is in effect, the data is sent in a
SANE_FRAME_GRAY frame. The optional frames sent by this backend are:
SANE_FRAME_G31D, SANE_FRAME_G32D, SANE_FRAME_G42D and SANE_FRAME_TEXT.
These frames are generated based on the compression and barcode options.
These frames are never sent in preview mode.
fake-inquiry
This option is used for debugging purposes and its use is not encouraged.
Essentially, it allows the backend to initialize in the absence of
a scanner. This is useful for development and not much else.
This option must be specified earlier in the configuration file than
the devices which are to be "faked".
FILES
/etc/sane.d/bh.conf
The backend configuration file (see also description of
SANE_CONFIG_DIR
below).
/usr/lib/sane/libsane-bh.a
The static library implementing this backend.
/usr/lib/sane/libsane-bh.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_BH
If the library was compiled with debug support enabled, this
environment variable controls the debug level for this backend. E.g.,
a value of 255 requests all debug output to be printed. Smaller
levels reduce verbosity.
SUPPORTED FEATURES
ADF support
With document scanners, automatic document feeder (ADF) support is a key
feature. The backend supports the ADF by default and returns
SANE_STATUS_NO_DOCS
when the out-of-paper condition is detected. The SANE frontend
scanadf
is a command line frontend that supports multi-page scans. It has been
used successfully with this backend. The SANE frontend
xsane
is an improved GUI frontend by Oliver Rauch. Support for multi-page
scans is included in xsane version 0.35 and above.
Duplex scanning
Some models, such as the COPISCAN II 6338, support duplex scanning. That
is, they scan both sides of the document during a single pass through the
scanner (the scanner has two cameras). This backend supports duplex
scanning (with the
--duplex
option). The front and back page images are delivered consecutively
as if they were separately scanned pages.
Hardware compression
The scanner is capable of compressing the data into several industry
standard formats (CCITT G3, CCITT G3-2D, CCITT G4). This results in
increased performance as less data is passed from the scanner to the
host over the SCSI bus. The backend supports these compression formats
via the
--g31d, --g32d, --g42d
options, respectively. Many SANE frontends are not equipped to deal with
these formats, however. The SANE frontend
scanadf
supports these optional frame formats. The compressed image data
is written directly to a file and can then be processed by a scan-script
using the
--scan-script
option. Examples of this are given on the scanadf homepage.
Automatic Border Detection
The scanner can automatically detect the paper size and adjust the
scanning window geometry appropriately. The backend supports this
useful feature with the
--autoborder
option. It is enabled by default.
Batch Mode Scanning
The batch scan mode allows for maximum throughput. The Set Window
parameters must remain constant during the entire batch.
Icon Generation
The Icon function generates a thumbnail of the full page image, that can be
transferred as if it were a separate page. This allows the host to
quickly display a thumbnail representation during the scanning operation.
Perhaps this would be a great way of implementing a preview scan, but
since a normal scan is so quick, it might not be worth the trouble.
Multiple Sections
Multiple sections (scanning sub-windows) can be defined for the front and
back pages. Each section can have different characteristics (e.g. geometry,
compression). The sections are returned as if they were separately
scanned images. Additionally sections can be used to greatly enhance the
accuracy and efficiency of the barcode/patchcode decoding process by
limiting the search area to a small subset of the page. Most Copiscan II
series scanners support up to 8 user-defined sections.
Support Barcode/Patchcode Decoding
The RSC unit can recognize Bar and Patch Codes of various types embedded
in the scanned image. The codes are decoded and the data is returned to
the frontend as a text frame. The text is encoded in xml and contains
a great deal of information about the decoded data such as the location
where it was found, its orientation, and the time it took to find.
Further information on the content of this text frame as well as some
barcode decoding examples can be found on the backend homepage.
LIMITATIONS
Decoding a single barcode type per scan
The RSC unit can search for up to six different barcode types at a time.
While the code generally supports this as well, the
--barcode-search-bar
option only allows the user to specify a single barcode type.
Perhaps another option which allows a comma separated list of barcode
type codes could be added to address this.
Scanning a fixed number of pages in batch mode
The separation of front and back end functionality in SANE presents a
problem in supporting the 'cancel batch' functionality in the scanner.
In batch mode, the scanner is always a page ahead of the host. The host,
knowing ahead of time which page will be the last, can cancel batch mode
prior to initiating the last scan command. Currently, there is no mechanism
available for the frontend to pass this knowledge to the backend.
If batch mode is enabled and the --end-count terminates a scanadf session,
an extra page will be pulled through the scanner, but is neither read
nor delivered to the frontend. The issue can be avoided by specifying
--batch=no when scanning a fixed number of pages.
Revision 1.2 Patch detector
There is an enhanced patchcode detection algorithm available in the RSC
with revision 1.2 or higher that is faster and more reliable than the
standard Bar/Patch code decoder. This is not currently supported.
OPTIONS
Scan Mode Options:
--preview[=(yes|no)] [no]
Request a preview-quality scan. When preview is set to yes image
compression is disabled and the image is delivered in a
SANE_FRAME_GRAY frame.
--mode lineart|halftone [lineart]
Selects the scan mode (e.g., lineart,monochrome, or color).
--resolution 200|240|300dpi [200]
Sets the resolution of the scanned image. Each scanner model supports
a list of standard resolutions; only these resolutions can be used.
--compression none|g31d|g32d|g42d [none]
Sets the compression mode of the scanner. Determines the type of data
returned from the scanner. Values are:
none
- uncompressed data - delivered in a SANE_FRAME_GRAY frame
g31d
- CCITT G3 1 dimension (MH) - delivered in a SANE_FRAME_G31D frame
g32d
- CCITT G3 2 dimensions (MR, K=4) - delivered in a SANE_FRAME_G32D frame
g42d
- CCITT G4 (MMR) - delivered in a SANE_FRAME_G42D frame
NOTE: The use of g31d, g32d, and g42d compression values causes the backend
to generate optional frame formats which may not be supported by all SANE
frontends.
Geometry Options:
--autoborder[=(yes|no)] [yes]
Enable/Disable automatic image border detection. When enabled, the RSC unit
automatically detects the image area and sets the window geometry to match.
Selects the scan source (such as a document feeder). This option is provided
to allow multiple image scans with xsane; it has no other purpose.
--batch[=(yes|no)] [no]
Enable/disable batch mode scanning. Batch mode allows scanning at maximum throughput
by buffering within the RSC unit. This option is recommended when performing multiple
pages scans until the feeder is emptied.
--duplex[=(yes|no)] [no]
Enable duplex (dual-sided) scanning. The scanner takes an image of each side
of the document during a single pass through the scanner. The front page is
delivered followed by the back page. Most options, such as compression,
affect both the front and back pages.
--timeout-adf 0..255 [0]
Sets the timeout in seconds for the automatic document feeder (ADF).
The value 0 specifies the hardware default value which varies based
on the scanner model.
--timeout-manual 0..255 [0]
Sets the timeout in seconds for semi-automatic feeder. The value 0 specifies
the hardware default value which varies based on the scanner model.
--check-adf[=(yes|no)] [no]
Check ADF Status prior to starting scan using the OBJECT POSITION command.
Note that this feature requires RSC firmware level 1.5 or higher and dip
switch 4 must be in the on position. NOTE: This option has not been tested
extensively and may produce undesirable results.
Enhancement:
--control-panel[=(yes|no)] [yes]
Enables the scanner's control panel for selecting image enhancement
parameters. When the option is set to no the following options are
used to control image enhancement. See the Bell+Howell scanner users'
guide for complete information on ACE functionality.
--ace-function -4..4 [3]
Specify the Automatic Contrast Enhancement (ACE) Function.
--ace-sensitivity 0..9 [5]
Specify the Automatic Contrast Enhancement (ACE) Sensitivity.
--brightness 0..255 [0]
Controls the brightness of the acquired image. Ignored for ACE
capable scanners.
--threshold 0..255 [0]
Select minimum-brightness to get a white point. Ignored for ACE
capable scanners.
--contrast 0..255 [inactive]
Controls the contrast of the acquired image. This option is not
currently used by the scanner (and perhaps never will be).
--negative[=(yes|no)] [no]
Swap black and white, yielding a reverse-video image.
Icon:
--icon-width 0..3600pel (in steps of 8) [0]
Width of icon (thumbnail) image in pixels.
--icon-length 0..3600pel (in steps of 8) [0]
Length of icon (thumbnail) image in pixels.
Barcode Options:
--barcode-search-bar <see list> [none]
Specifies the barcode type to search for. If this option is
not specified, or specified with a value of none, then the barcode decoding
feature is completely disabled. The valid barcode type are:
Number of times that the RSC performs the decoding algorithm. Specify
the smallest number possible to increase performance. If you are having
trouble recognizing barcodes, it is suggested that you increase this option
to its maximum value (7).
--barcode-search-mode <see list> [horiz-vert]
Chooses the orientation of barcodes to be searched. The valid orientations
are:
horiz-vert horizontal vertical vert-horiz
--barcode-hmin 0..1660mm [5]
Sets the barcode minimum height in millimeters (larger values increase
recognition speed). Of course the actual barcodes in the document must be
of sufficient size.
--barcode-search-timeout 20..65535us [10000]
Sets the timeout for barcode searching in milliseconds. When the timeout
expires, the decoder will stop trying to decode barcodes.
--section <string> []
Specifies a series of image sections. A section can be used to gather
a subset image or to provide a small area for barcode decoding.
Each section is specified in the following format (units are in millimeters):
Multiple sections can be specified by separating them with commas.
For example
76.2x25.4+50.8+0:frontbar
identifies an area 3 inches wide and 1 inch high with a top left corner
at the top of the page two inches from the left hand edge of the page.
This section will be used for barcode decoding on the front page only.
For example
50.8x25.4+25.4+0:frontbar:front:g42d
identifies an area 2 inches wide and 1 inch high with a top left corner
at the top of the page one inch from the left hand edge of the page.
This section will be used for barcode decoding on the front page as well
as generating an image compressed in g42d format.
Ordinarily barcodes are searched in the entire image. However, when you
specify sections all barcode searching is done within the specific sections
identified. This can significantly speed up the decoding process.
The following functioncodes are available:
front
- generate an image for the front page section
back
- generate an image for the back page section
frontbar
- perform barcode search in front page section
backbar
- perform barcode search in back page section
frontpatch
- perform patchcode search in front page section
backpatch
- perform patchcode search in back page section
none
- use no image compression
g31d
- use Group 3 1 dimension image compression
g32d
- use Group 3 2 dimensions image compression
g42d
- use Group 4 2 dimensions image compression
If you omit a compression functioncode, the full page compression setting
is used. If you specify multiple compression functioncodes, only the
last one is used.
--barcode-relmax 0..255 [0]
Specifies the maximum relation from the widest to the smallest bar.
--barcode-barmin 0..255 [0]
Specifies the minimum number of bars in Bar/Patch code.
--barcode-barmax 0..255 [0]
Specifies the maximum number of bars in a Bar/Patch code.
--barcode-contrast 0..6 [3]
Specifies the image contrast used in decoding. Use higher values when
there are more white pixels in the code.
--barcode-patchmode 0..1 [0]
Controls Patch Code detection.
BUGS
This is a new backend; detailed bug reports are welcome -- and expected ;)
If you have found something that you think is a bug, please attempt to
recreate it with the SANE_DEBUG_BH environment variable set to
255, and send a report detailing the conditions surrounding the bug to
sane-devel@lists.alioth.debian.org.
The sane-bh backend was written by Tom Martone, based on the sane-ricoh
backend by Feico W. Dillema and the bnhscan program by Sean Reifschneider
of tummy.com ltd. Some 8000 enhancements added by Mark Temple.
