Section: SANE Scanner Access Now Easy (5)
Updated: 13 Jul 2008
sane-dmc - SANE backend for the Polaroid Digital Microscope Camera
library implements a SANE (Scanner Access Now Easy) backend that
provides access to the Polaroid Digital Microscope Camera.
This backend expects device names of the form:
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
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.
This mode corresponds to the 270-by-201 pixel grey-scale viewfinder image.
This image is acquired very quickly.
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.
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 xscanimage does not work in Super Resolution mode.
and the non-preview modes of
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 milliseconds. 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" settings on Polaroid's Windows and Mac software.
The contents of the
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:
# this is a comment
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
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
to "/tmp/config:" would result in directories
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 128 requests all debug output to be printed. Smaller
levels reduce verbosity.
In the "Full Frame" and "Raw" modes, images must be read in units
of entire lines. The driver performs no buffering 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_STATUS_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
David F. Skoll
The backend is derived from
by David Mosberger