NAME

       sane-rts8891 - SANE backend for rts8891 based scanners

DESCRIPTION

       The sane-rts8891 library implements a SANE (Scanner Access Now Easy) backend that provides
       access to scanners based on the rts8891 ASIC.

       The scanners that work with this backend are:

                 Vendor Model           status
              ----------------------  -----------
                Umax Astra 4400       untested
                Umax Astra 4450       untested
                HP scanjet 4000c      good
                HP scanjet 4470c      good

       The options the backend supports can either be selected through command  line  options  to
       programs like scanimage or through GUI elements in xscanimage or xsane.

       If  you  have any strange behavior, please report to the backend maintainer or to the SANE
       mailing list.

       Valid command line options and their syntax can be listed by using
              scanimage --help -d rts8891

       Scan Mode Options

       --mode selects the basic mode of operation of the scanner valid choices are R Color , Gray
              and  Lineart The default mode is Color. The Lineart mode is black and white only (1
              bit).  Grayscale will produce 256 levels of gray (8 bits). Color  mode  allows  for
              over 16 million different colors produced from 24 bits of color information.

       --resolution
              selects  the resolution for a scan. The horizontal and vertical resolutions are set
              by the value of this option. The scanner is capable of  the  following  resolutions
              for the specified option value:

                Value   Hor. Resolution  Vert. Resolution
                -----   ---------------  -------------------
                75      75dpi            75dpi
                150     150dpi           150dpi
                300     300dpi           300dpi
                600     600dpi           600dpi
                1200    1200dpi          1200dpi

       --preview
              requests  a  preview scan. The resolution used for that scan is 75 dpi and the scan
              area and the scan mode are as specified through their options, or  the  default  if
              not specified. The default value for preview mode is "no".

       --threshold
              selects  the   minimum-brightness  to get a white point. The threshold is only used
              with Lineart mode scans.  It is specified as a percentage in the range 0..100%  (in
              steps of 1).  The default value of the threshold option is 50.

CONFIGURATION FILE

       The  configuration  file /etc/sane.d/rts8891.conf contains the usb device ids of supported
       scanners (eg usb 0x043d 0x007c) and scanner configuration options.  Empty lines and  lines
       starting with a hash mark (#) are ignored.

       The options supported are allowsharing , modelnumber

       Option

       allowsharing  enables  or not the sharing of the scanner between multiple frontends at the
       same time.

       modelnumber is used to force the reported model by the backend and is only useful  in  the
       case of a scanner which NVRAM has been erased.
              0 to report a HP4470c.
              1 to report a HP4400c.
              2 to report an Astra 4400.

FILES

       /usr/lib/arch_triplet/sane/libsane-rts8891.a
              The static library implementing this backend.

       /usr/lib/arch_triplet/sane/libsane-rts8891.so
              The  shared  library  implementing  this  backend  (present on systems that support
              dynamic loading).

ENVIRONMENT

       SANE_DEBUG_RTS8891 SANE_DEBUG_RTS8891_LOW SANE_DEBUG_RTS88XX_LIB
              If the library was compiled with debug support enabled, these environment variables
              controls  the debug level for this backend. E.g., a value of 255 requests all debug
              output to be printed. Smaller levels reduce verbosity.

LIMITATIONS

       Scanners of the same model exist with different sensors, due to lack of data (ie USB logs)
       some  sensors  are  better  supported than others. At least 75 dpi mode is working for any
       model. Sharing the scanner between  several  frontends  at  the  same  time  (allowsharing
       option) may not work on some USB controllers.

       XPA is no (yet) supported.

BUGS

       No bugs currently known.

SEE ALSO

       sane-scsi(5), scanimage(1), xscanimage(1), xsane(1), sane(7)

AUTHOR

       This backend has been developed by Stéphane Voltz.
              http://stef.dev.free.fr/sane/rts8891

CREDITS

       Many thanks go to:
              Laurent  Fournier who donated me a HP4470c.  Vladimir Sysoev and "TheUnruly Squash"
              for the time they spent recording USB activity and testing the experimental version
              on HP4400 models.

                                            8 Dec 2008                            sane-rts8891(5)