sane-test(5)             SANE Scanner Access Now Easy             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 scanning and setting options.

       The idea is not only to find bugs in frontends but also to show all
       capabilities of SANE.  Therefore sane-test implements 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 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 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 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.

       If option invert-endianess 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
       endianess.

       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 microseconds the
       backends waits after each transfer of a buffer.  This option is useful
       to find timing-related bugs, especially 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 statii.

       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) parameters are
       returned as long as the scan hasn't been started.  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 numbered.
       (3/6) means: this is option 3 of 6.  The numbering scheme is intended
       for easier detection of options not displayed 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.

       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 automatically 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
       There are 3 string test options in total.

       Option string (1/3) is a string test option without constraint.

       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 provided 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 resolution and geometry can be useful to test the
              handling of big file sizes.


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

       /usr/local/lib/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 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 separator character, then the default directories
              are searched after the explicitly specified directories.  For
              example, setting SANE_CONFIG_DIR to "/tmp/config:" would result
              in directories "tmp/config", ".", 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 verbosity of the output.

              Example: export SANE_DEBUG_TEST=4


SEE ALSO
       sane(7), 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



                                  14 Jul 2008                     sane-test(5)
