sane-bh - SANE backend for Bell+Howell Copiscan II series document
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 email@example.com 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
The latest backend release, additional information and helpful hints
are available from the backend homepage:
This backend expects device names of the form:
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.
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.
The following options can be specified in the bh.conf file.
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.
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".
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).
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.
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.
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.
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.
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 (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-
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.
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
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
Scan Mode Options:
Request a preview-quality scan. When preview is set to yes
image compression is disabled and the image is delivered in a
--mode lineart|halftone [lineart]
Selects the scan mode (e.g., lineart,monochrome, or color).
--resolution 200|240|300dpi 
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
g32d - CCITT G3 2 dimensions (MR, K=4) - delivered in a
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.
Enable/Disable automatic image border detection. When enabled,
the RSC unit automatically detects the image area and sets the
window geometry to match.
--paper-size Custom|Letter|Legal|A3|A4|A5|A6|B4|B5 [Custom]
Specify the scan window geometry by specifying the paper size of
the documents to be scanned.
--tl-x 0..297.18mm 
Top-left x position of scan area.
--tl-y 0..431.8mm 
Top-left y position of scan area.
--br-x 0..297.18mm [297.18]
Bottom-right x position of scan area.
--br-y 0..431.8mm [431.8]
Bottom-right y position of scan area.
--source Automatic Document Feeder|Manual Feed Tray [Automatic Document
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.
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.
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
--timeout-adf 0..255 
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 
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 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.
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-function -4..4 
Specify the Automatic Contrast Enhancement (ACE) Function.
--ace-sensitivity 0..9 
Specify the Automatic Contrast Enhancement (ACE) Sensitivity.
--brightness 0..255 
Controls the brightness of the acquired image. Ignored for ACE
--threshold 0..255 
Select minimum-brightness to get a white point. Ignored for ACE
--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).
Swap black and white, yielding a reverse-video image.
--icon-width 0..3600pel (in steps of 8) 
Width of icon (thumbnail) image in pixels.
--icon-length 0..3600pel (in steps of 8) 
Length of icon (thumbnail) image in pixels.
--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
--barcode-search-count 1..7 
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
--barcode-hmin 0..1660mm 
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 
Sets the timeout for barcode searching in milliseconds. When
the timeout expires, the decoder will stop trying to decode
--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
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 
Specifies the maximum relation from the widest to the smallest
--barcode-barmin 0..255 
Specifies the minimum number of bars in Bar/Patch code.
--barcode-barmax 0..255 
Specifies the maximum number of bars in a Bar/Patch code.
--barcode-contrast 0..6 
Specifies the image contrast used in decoding. Use higher
values when there are more white pixels in the code.
--barcode-patchmode 0..1 
Controls Patch Code detection.
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(7), sane-scsi(5), scanimage(1), scanadf(1)
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
10 Jul 2008 sane-bh(5)