File: sanedoc.txt

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python-sane documentation
*************************

The sane module is a Python interface to the SANE (Scanning is Now
Easy) library, which provides access to various raster scanning
devices such as flatbed scanners and digital cameras.  For more
information about SANE, consult the SANE website at www.sane-
project.org. Note that this documentation doesn't duplicate all the
information in the SANE documentation, which you must also consult to
get a complete understanding.

This module has been originally developed by A.M. Kuchling, it is
currently maintained by Sandro Mani.

* Indices

* Reference

* Example


Indices
=======

* *Index*

* *Search Page*


Reference
=========

sane.init()

   Initialize sane.

   Returns:
      A tuple "(sane_ver, ver_maj, ver_min, ver_patch)".

   Raises _sane.error:
      If an error occurs.

sane.get_devices(localOnly=False)

   Return a list of 4-tuples containing the available scanning
   devices. If *localOnly* is *True*, only local devices will be
   returned. Each tuple is of the format "(device_name, vendor, model,
   type)", with:

   * *device_name* -- The device name, suitable for passing to
     "sane.open()".

   * *vendor* -- The device vendor.

   * *mode* -- The device model vendor.

   * *type* -- the device type, such as ""virtual device"" or
     ""video camera"".

   Returns:
      A list of scanning devices.

   Raises _sane.error:
      If an error occurs.

sane.open(devname)

   Open a device for scanning. Suitable values for devname are
   returned in the first item of the tuples returned by
   "sane.get_devices()".

   Returns:
      A "SaneDev" object on success.

   Raises _sane.error:
      If an error occurs.

sane.exit()

   Exit sane.

class class sane.SaneDev(devname)

   Class representing a SANE device. Besides the functions documented
   below, the class has some special attributes which can be read:

   * *devname*        -- The scanner device name (as passed to

        "sane.open()").

   * *sane_signature* -- The tuple "(devname, brand, name, type)".

   * *scanner_model*  -- The tuple "(brand, name)".

   * *opt*            -- Dictionary of options.

   * *optlist*        -- List of option names.

   * *area*           -- Scan area.

   Furthermore, the scanner options are also exposed as attributes,
   which can be read and set:

      print scanner.mode
      scanner.mode = 'Color'

   An "Option" object for a scanner option can be retrieved via
   "__getitem__()", i.e.:

      option = scanner['mode']

   arr_scan()

      Convenience method which calls "SaneDev.start()" followed by
      "SaneDev.arr_snap()".

   arr_snap()

      Read image data and return a 3d numpy array of the shape
      "(nbands, width, height)".

      Returns:
         A "numpy.array" object.

      Raises:
         * **_sane.error** -- If an error occurs.

         * **RuntimeError** -- If *numpy* cannot be imported.

   cancel()

      Cancel an in-progress scanning operation.

   close()

      Close the scanning device.

   fileno()

      Returns:
         The file descriptor for the scanning device, if any.

      Raises _sane.error:
         If an error occurs.

   get_options()

      Returns:
         A list of tuples describing all the available options.

   get_parameters()

      Returns a 5-tuple holding all the current device settings:
      "(format, last_frame, (pixels_per_line, lines), depth,
      bytes_per_line)"

      * *format*          -- One of ""grey"", ""color"", ""red"",

           ""green"", ""blue"" or ""unknown format"".

      * *last_frame*      -- Whether this is the last frame of a
        multi frame

           image.

      * *pixels_per_line* -- Width of the scanned image.

      * *lines*           -- Height of the scanned image.

      * *depth*           -- The number of bits per sample.

      * *bytes_per_line*  -- The number of bytes per line.

      Returns:
         A tuple containing the device settings.

      Raises _sane.error:
         If an error occurs.

      Note: Some backends may return different parameters depending on
      whether "SaneDev.start()" was called or not.

   multi_scan()

      Returns:
         A "_SaneIterator" for ADF scans.

   scan()

      Convenience method which calls "SaneDev.start()" followed by
      "SaneDev.snap()".

   snap(no_cancel=False)

      Read image data and return a "PIL.Image" object. An RGB image is
      returned for multi-band images, an L image for single-band
      images. "no_cancel" is used for ADF scans by "_SaneIterator".

      Returns:
         A "PIL.Image" object.

      Raises:
         * **_sane.error** -- If an error occurs.

         * **RuntimeError** -- If *PIL.Image* cannot be imported.

   start()

      Initiate a scanning operation.

      Throws _sane.error:
         If an error occurs, for instance if an option is set to an
         invalid value.

class class sane.Option(args, scanDev)

   Class representing a SANE option. These are returned by a
   "SaneDev.__getitem__()" lookup of an option on the device, i.e.:

      option = scanner["mode"]

   The "Option" class has the following attributes:

      * *index* -- Number from "0" to "n", giving the option number.

      * *name* -- A string uniquely identifying the option.

      * *title* -- Single-line string containing a title for the
        option.

      * *desc* -- A long string describing the option, useful as a
        help

           message.

      * *type* -- Type of this option: "TYPE_BOOL", "TYPE_INT",

           "TYPE_STRING", etc.

      * *unit* -- Units of this option. "UNIT_NONE", "UNIT_PIXEL",
        etc.

      * *size* -- Size of the value in bytes.

      * *cap* -- Capabilities available: "CAP_EMULATED",
        "CAP_SOFT_SELECT",

           etc.

      * *constraint* -- Constraint on values. Possible values:

        * None : No constraint

        * "(min,max,step)" : Range

        * list of integers or strings: listed of permitted values

   is_active()

      Returns:
         Whether the option is active.

   is_settable()

      Returns:
         Whether the option is settable.

class class sane._SaneIterator(device)

   Iterator for ADF scans.


Example
=======

   #!/usr/bin/env python

   from __future__ import print_function
   import sane
   import numpy
   from PIL import Image

   #
   # Change these for 16bit / grayscale scans
   #
   depth = 8
   mode = 'color'

   #
   # Initialize sane
   #
   ver = sane.init()
   print('SANE version:', ver)

   #
   # Get devices
   #
   devices = sane.get_devices()
   print('Available devices:', devices)

   #
   # Open first device
   #
   dev = sane.open(devices[0][0])

   #
   # Set some options
   #
   params = dev.get_parameters()
   try:
       dev.depth = depth
   except:
       print('Cannot set depth, defaulting to %d' % params[3])

   try:
       dev.mode = mode
   except:
       print('Cannot set mode, defaulting to %s' % params[0])

   try:
       dev.br_x = 320.
       dev.br_y = 240.
   except:
       print('Cannot set scan area, using default')

   params = dev.get_parameters()
   print('Device parameters:', params)

   #
   # Start a scan and get a PIL.Image object
   #
   dev.start()
   im = dev.snap()
   im.save('test_pil.png')


   #
   # Start another scan and get a numpy array object
   #
   # Initiate the scan and get a numpy array
   dev.start()
   arr = dev.arr_snap()
   print("Array shape: %s, size: %d, type: %s, range: %d-%d, mean: %.1f, stddev: "
         "%.1f" % (repr(arr.shape), arr.size, arr.dtype, arr.min(), arr.max(),
                   arr.mean(), arr.std()))

   if arr.dtype == numpy.uint16:
       arr = (arr / 255).astype(numpy.uint8)

   if params[0] == 'color':
       im = Image.frombytes('RGB', arr.shape[1:], arr.tostring(), 'raw', 'RGB', 0,
                            1)
   else:
       im = Image.frombytes('L', arr.shape[1:], arr.tostring(), 'raw', 'L', 0, 1)

   im.save('test_numpy.png')

   #
   # Close the device
   #
   dev.close()