The images are written to output files, specified by the --output-file option. These files are typically written in one of the PNM (portable aNyMaP) formats (PBM for black-and-white images, PGM for grayscale images, and PPM for color images). Several optional frame formats (SANE_FRAME_JPEG, SANE_FRAME_G31D, SANE_FRAME_G32D, SANE_FRAME_G42D, and SANE_FRAME_TEXT) are supported. In each case, the data is written out to the output file as-is without a header. Unrecognized frame formats are handled in the same way, although a warning message is printed in verbose mode.
Typically, the optional frame formats are used in conjunction with a scan script (specified by the --scanscript option) which is invoked for each acquired image. The script is provided with a series of environment variables which describe the parameters and format of the image file.
scanadf accesses image acquisition devices through the SANE (Scanner Access Now Easy) interface and can thus support any device for which there exists a SANE backend (try "apropos sane-" to get a list of available backends).
The -d or --device-name options must be followed by a SANE device-name. A (partial) list of available devices can be obtained with the --list-devices option (see below). If no device-name is specified explicitly, scanadf will attempt to open the first available device.
The -h or --help options request help information. The information is printed on standard output and in this case, no attempt will be made to acquire an image.
The -L or --list-devices option requests a (partial) list of devices that are available. The list is not complete since some devices may be available, but are not listed in any of the configuration files (which are typically stored in directory /usr/etc/sane.d). This is particularly the case when accessing scanners through the network. If a device is not listed in a configuration file, the only way to access it is by its full device name. You may need to consult your system administrator to find out the names of such devices.
The -v or --verbose options increase the verbosity of the operation of scanadf. The option may be specified repeatedly, each time increasing the verbosity level.
The -V or --version option requests that scanadf print the program and package name, as well as the version number of the SANE distribution that it came with.
The -o or --output-file option specifies a format string used to generate the name of file to write the image data to. You can use %d replacement in the output file name; this will be replaced with the current page number. The default format string is image-%04d.
The -N or --no-overwrite option prevents scanadf from overwriting existing image files.
The -S or --scan-script option specifies the name of script to run after each scanned image is acquired. The script receives the name of the image output file as its first and only command line argument. Additionally the scan script can reference the following environment variables to get information about the parameters of the image.
If the --scipt-wait option is given, scanadf will wait until all scan-scripts have been finished before exiting. That will be useful if scanadf is used in conjunction with tools to modify the scanned images.
The -s or --start-count option specifies the page number of first scanned image.
The -e or --end-count option specifies the last page number to scan. Using this option, you can request a specific number of pages to be scanned, rather than scanning until there are no more images available.
The -r or --raw option specifies that the raw image data be written to the output file as-is without interpretation. This disables the writing of the PNM header for basic frame types. This feature is usually used in conjunction with the --scan-script option where the scan script uses the environment variables to understand the format and parameters of the image and converts the file to a more useful format. NOTE: With support for the optional frame types and the default handling of unrecognized frametypes, this option becomes less and less useful.
As you might imagine, much of the power of scanadf comes from the fact that it can control any SANE backend. Thus, the exact set of command-line options depends on the capabilities of the selected device. To see the options for a device named dev, invoke scanadf via a command-line of the form:
The documentation for the device-specific options printed by --help is explained in the manual page for scanimage.
This program relies on the backend to return the SANE_STATUS_NO_DOCS status code when the automatic document feeder is out of paper. Use of this program with backends that do not support ADFs (e.g. flatbed scanners) will likely result in repeated scans of the same document. In this case, it is essential to use the start-count and end-count to control the number of images acquired.
Only a subset of the SANE backends support feeders and return SANE_STATUS_NO_DOCS appropriately. Backends which are known to work at this time are: