sane-test(5)              (14 Jul 2008)              sane-test(5)

     NAME
          sane-test - SANE backend for testing frontends

     DESCRIPTION
          The sane-test library implements a SANE (Scanner Access Now
          Easy) backend that allows testing the SANE installation and
          SANE frontends.  It provides access to a (nearly) unlimited
          number of virtual devices.  There is no support for real
          scanners or cameras.  However, the backend simulates scan-
          ning and setting options.

          The idea is not only to find bugs in frontends but also to
          show all capabilities of SANE.  Therefore sane-test imple-
          ments functions and options that are not (or seldom) found
          in other backends.

          The backend is commented out in /etc/sane.d/dll.conf, so
          either the comment character must be removed or the backend
          must be called explicitly.  E.g.  scanimage -d test or
          xscanimage test.

     SCAN MODE OPTIONS
          Option mode selects the scan mode (Gray or Color).

          Option depth determines the number of bits per sample (1. 8,
          or 16).  Keep in mind, that this value refers to the sample,
          not the pixel.  So depth=16 results in 48 bits per pixel in
          color mode. The most usual combinations are mode=Gray,
          depth=1 for lineart, mode=Gray, depth=8 for gray and
          mode=Color, depth=8 for color mode.  The combination of
          color and 1-bit mode is quite obscure (8 colors) but allowed
          in the SANE standard. However, the meaning of bits is not
          defined. Currently 1 = high intensity and 0 = low intensity
          is used.

          Setting option hand-scanner results in the test-backend
          behaving like a hand-scanner.  Hand-scanners do not know the
          image height a priori.  Instead, they return a height of -1.
          Setting this option allows one to test whether a frontend
          can handle this correctly.  This option also enables a fixed
          width of 11 cm.

          Setting option three-pass simulates a three-pass scanner.
          Older color scanners needed to scan the image once per color
          (reg/green/blue) to get the full image.  Therefore, in this
          mode three single frames are transmitted in color mode.

          Option three-pass-order provides support for changing the

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          order of the three frames (see option three-pass above).  A
          frontend should support all orders.

          Option resolution sets the resolution of the image in dots
          per inch.

          Option source can be used to simulate an Automatic Document
          Feeder (ADF). After 10 scans, the ADF will be "empty".

     SPECIAL OPTIONS
          Option test-picture allows one to set the image that's
          returned to the frontend.  While "Solid white" and "Solid
          black" are quite obvious, the other options need some more
          explanation.  Color patterns are used to determine if all
          modes and their colors are represented correctly by the
          frontend.  The grid should look like the same in every mode
          and resolution.  A table of all the test pictures can be
          found at:
          http://www.meier-geinitz.de/sane/test-backend/test-pictures.html.
          .}f

          If option invert-endianness is set, the upper and lower
          bytes of image data in 16 bit modes are exchanged.  This
          option can be used to test the 16 bit modes of frontends,
          e.g. if the frontend uses the correct endianness.

          If option read-limit is set, the maximum amount of data
          transferred with each call to sane_read() is limited.

          Option read-limit-size sets the limit for option read-limit.
          A low limit slows down scanning.  It can be used to detect
          errors in frontend that occur because of wrong assumptions
          on the size of the buffer or timing problems.

          Option read-delay enables delaying data to the frontend.

          Option read-delay-duration selects the number of microsec-
          onds the backends waits after each transfer of a buffer.
          This option is useful to find timing-related bugs, espe-
          cially if used over the network.

          If option read-return-value is different from "Default", the
          selected status will be returned by every call to
          sane_read().  This is useful to test the frontend's handling
          of the SANE statuses.

          If option ppl-loss is different from 0, it determines the
          number of pixels that are "lost" at the end of each line.
          That means, lines are padded with unused data.

          Option fuzzy-parameters selects that fuzzy (inexact) parame-
          ters are returned as long as the scan hasn't been started.

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          This option can be used to test if the frontend uses the
          parameters it got before the start of the scan (which it
          shouldn't).

          Option non-blocking determines if non-blocking IO for
          sane_read() should be used if supported by the frontend.

          If option select-fd is set, the backend offers a select
          filedescriptor for detecting if sane_read() will return
          data.

          If option enable-test-options is set, a fairly big list of
          options for testing the various SANE option types is
          enabled.

          Option print-options can be used to print a list of all
          options to standard error.

     GEOMETRY OPTIONS
          Option tl-x determines the top-left x position of the scan
          area.

          Option tl-y determines the top-left y position of the scan
          area.

          Option br-x determines the bottom-right x position of the
          scan area.

          Option br-y determines the bottom-right y position of the
          scan area.

     BOOL TEST OPTIONS
          There are 6 bool test options in total.  Each option is num-
          bered.  (3/6) means: this is option 3 of 6.  The numbering
          scheme is intended for easier detection of options not dis-
          played by the frontend (because of missing support or bugs).

          Option bool-soft-select-soft-detect (1/6) is a bool test
          option that has soft select and soft detect (and advanced)
          capabilities.  That's just a normal bool option.

          Option bool-hard-select-soft-detect (2/6) is a bool test
          option that has hard select and soft detect (and advanced)
          capabilities.  That means the option can't be set by the
          frontend but by the user (e.g. by pressing a button at the
          device).

          Option bool-hard-select (3/6) is a bool test option that has
          hard select (and advanced) capabilities.  That means the
          option can't be set by the frontend but by the user (e.g. by
          pressing a button at the device) and can't be read by the
          frontend.

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          Option bool-soft-detect (4/6) is a bool test option that has
          soft detect (and advanced) capabilities.  That means the
          option is read-only.

          Option bool-soft-select-soft-detect-emulated (5/6) is a Bool
          test option that has soft select, soft detect, and emulated
          (and advanced) capabilities.

          Option bool-soft-select-soft-detect-auto (6/6) is a Bool
          test option that has soft select, soft detect, and automatic
          (and advanced) capabilities.  This option can be automati-
          cally set by the backend.

     INT TEST OPTIONS
          There are 6 int test options in total.

          Option int (1/6) is an int test option with no unit and no
          constraint set.

          Option int-constraint-range (2/6) is an int test option with
          unit pixel and constraint range set.  Minimum is 4, maximum
          192, and quant is 2.

          Option int-constraint-word-list (3/6) is an int test option
          with unit bits and constraint word list set.

          Option int-constraint-array (4/6) is an int test option with
          unit mm and using an array without constraints.

          Option int-constraint-array-constraint-range (5/6) is an int
          test option with unit mm and using an array with a range
          constraint.  Minimum is 4, maximum 192, and quant is 2.

          Option int-constraint-array-constraint-word-list (6/6) is an
          int test option with unit percent and using an array a word
          list constraint.

     FIXED TEST OPTIONS
          There are 3 fixed test options in total.

          Option fixed (1/3) is a fixed test option with no unit and
          no constraint set.

          Option fixed-constraint-range (2/3) is a fixed test option
          with unit microsecond and constraint range set. Minimum is
          -42.17, maximum 32767.9999, and quant is 2.0.

          Option fixed-constraint-word-list (3/3) is a Fixed test
          option with no unit and constraint word list set.

     STRING TEST OPTIONS

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          There are 3 string test options in total.

          Option string (1/3) is a string test option without con-
          straint.

          Option string-constraint-string-list (2/3) is a string test
          option with string list constraint.

          Option string-constraint-long-string-list (3/3) is a string
          test option with string list constraint. Contains some more
          entries...

     BUTTON TEST OPTION
          Option button (1/1) is a Button test option. Prints some
          text...

     FILES
          /etc/sane.d/test.conf
               The backend configuration file (see also description of
               SANE_CONFIG_DIR below). The initial values of most of
               the basic SANE options can be configured in this file.
               A template containing all the default values is pro-
               vided together with this backend. One of the more
               interesting values may be number_of_devices.  It can be
               used to check the frontend's ability to show a long
               list of devices.  The config values concerning resolu-
               tion and geometry can be useful to test the handling of
               big file sizes.

          /usr/lib/x86_64-linux-gnu/sane/libsane-test.a
               The static library implementing this backend.

          /usr/lib/x86_64-linux-gnu/sane/libsane-test.so
               The shared library implementing this backend (present
               on systems that support dynamic loading).

     ENVIRONMENT
          SANE_CONFIG_DIR
               This environment variable specifies the list of direc-
               tories 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 direc-
               tory separator 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,

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               ., and /etc/sane.d being searched (in this order).

          SANE_DEBUG_TEST
               If the library was compiled with debug support enabled,
               this environment variable controls the debug level for
               this backend.  Higher debug levels increase the ver-
               bosity of the output.

               Example: export SANE_DEBUG_TEST=4

     SEE ALSO
          sane(7), scanimage(1), xscanimage(1)
          http://www.meier-geinitz.de/sane/test-backend/

     AUTHOR
          Henning Meier-Geinitz <henning@meier-geinitz.de>

     BUGS
          - config file values aren't tested for correctness

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