sane-dmc  -  SANE  backend for the Polaroid Digital Micro­
       scope Camera


DESCRIPTION

       The sane-dmc library implements a SANE (Scanner Access Now
       Easy) backend that provides access to the Polaroid Digital
       Microscope Camera.


DEVICE NAMES

       This backend expects device names of the form:

              special

       Where special is the UNIX path-name for the special device
       that  corresponds to the scanner.  The special device name
       must be a generic SCSI device  or  a  symlink  to  such  a
       device.  Under Linux, such a device name could be /dev/sga
       or /dev/sge, for example.


IMAGING MODES

       The Polaroid DMC supports a number of imaging modes.  This
       driver supports five of the imaging modes:

       Full Frame
              This mode corresponds to the 801-by-600 pixel full-
              color full-frame image.

       Viewfinder
              This mode corresponds to the 270-by-201 pixel grey-
              scale  viewfinder  image.   This  image is acquired
              very quickly.

       Raw    This mode  corresponds  to  the  1599-by-600  pixel
              "raw"  image  from the CCD.  It is grey-scale, with
              pixels alternating horizontally between red,  green
              and  blue stripes.  The pixels are twice as high as
              they are wide, so the image is distorted.

       Thumbnail
              This mode corresponds to the 80-by-60  pixel  full-
              color thumbnail image.

       Super Resolution
              This image is a 1599-by-1200 pixel full-color image
              constructed  by  filtering  and  interpolating  the
              "raw"  image.   The  filtering and interpolation is
              done in software, so this mode is very slow.  Also,
              this  mode  places restrictions on how the image is
              read which means that the "preview" mode of  xscan­
              image  does  not  work  in  Super  Resolution mode.
              (xcam and the non-preview modes  of  scanimage  and
              xscanimage work fine, however.)

       ASA Setting
              This setting adjusts the camera's sensitivity.  You
              can choose one of 25, 50, or 100 "equivalent"  ASA.

       Shutter Speed
              You  can select a shutter speed from 8 to 1000 mil­
              liseconds.  The shutter speed is quantized in units
              of 32 microseconds.

       White Balance
              You can choose one of "Daylight", "Incandescent" or
              "Fluorescent" white balances.  This  setting  more-
              or-less corresponds to the "Color Temperature" set­
              tings on Polaroid's Windows and Mac software.


CONFIGURATION

       The contents of the dmc.conf file  is  a  list  of  device
       names  that  correspond  to DMC scanners.  Empty lines and
       lines starting with a hash mark (#) are ignored.  A sample
       configuration file is shown below:

              /dev/scanner
              # this is a comment
              /dev/sge


FILES

       /etc/sane.d/dmc.conf
              The  backend  configuration file (see also descrip­
              tion of SANE_CONFIG_DIR below).

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

       /usr/lib/sane/libsane-dmc.so
              The shared library implementing this backend  (pre­
              sent 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 sepa­
              rator character, then the default  directories  are
              searched  after  the  explicitly specified directo­
              ries.   For  example,  setting  SANE_CONFIG_DIR  to
              "/tmp/config:"    would   result   in   directories
              "tmp/config", ".", and "/etc/sane.d" being searched


       SANE_DEBUG_DMC
              If  the  library  was  compiled  with debug support
              enabled, this  environment  variable  controls  the
              debug level for this backend.  E.g., a value of 128
              requests all debug output to be  printed.   Smaller
              levels reduce verbosity.


BUGS

       In  the  "Full Frame" and "Raw" modes, images must be read
       in units of entire lines.  The driver performs no  buffer­
       ing  in  these  modes; if you ask sane_read to read a non-
       integral number of lines, it may read less  than  you  ask
       for.   If  you  ask  sane_read  to read less than a single
       line, it returns SANE_STATUS_INVAL.

       In the "Super Resolution" mode, images  must  be  read  in
       units  of  two  lines (3198 pixels or 9594 bytes.)  If you
       try to  read  less  than  two  lines,  you  get  SANE_STA­
       TUS_INVAL.  The Super Resolution mode is very slow.

       In  the  "Viewfinder"  and  "Thumbnail"  modes, the entire
       image must be read in one SCSI transfer.   In  this  case,
       the  driver  performs buffering and you can read the image
       in as small an increment as you like.


SEE ALSO

       sane(7), sane-scsi(5)


AUTHOR

       David F. Skoll

       The backend is derived from sane-hp by David Mosberger


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