Provided by: libsane_1.0.17-1ubuntu4_i386 bug

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 seldomly) 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
       explicitely.  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.

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 reprented 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 tranferred 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  inetended
       for  easier detection of options not displayed by the frontend (bevause
       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/lib/sane/libsane-test.a
              The static library implementing this backend.

       /usr/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