TIFFOpen,  TIFFFdOpen, TIFFClientOpen - open a TIFF file for reading or


       #include <tiffio.h>

       TIFF* TIFFOpen(const char *filename, const char *mode)
       TIFF* TIFFFdOpen(const int fd, const char *filename, const char *mode)

       typedef tsize_t (*TIFFReadWriteProc)(thandle_t, tdata_t, tsize_t);
       typedef toff_t (*TIFFSeekProc)(thandle_t, toff_t, int);
       typedef int (*TIFFCloseProc)(thandle_t);
       typedef toff_t (*TIFFSizeProc)(thandle_t);
       typedef int (*TIFFMapFileProc)(thandle_t, tdata_t*, toff_t*);
       typedef void (*TIFFUnmapFileProc)(thandle_t, tdata_t, toff_t);

       TIFF* TIFFClientOpen(const char *filename, const char *mode,  thandle_t
       clientdata,  TIFFReadWriteProc  readproc,  TIFFReadWriteProc writeproc,
       TIFFSeekProc seekproc, TIFFCloseProc closeproc, TIFFSizeProc  sizeproc,
       TIFFMapFileProc mapproc, TIFFUnmapFileProc unmapproc)


       TIFFOpen  opens a TIFF file whose name is filename and returns a handle
       to be used in subsequent calls to routines in  libtiff.   If  the  open
       operation  fails,  then zero is returned.  The mode parameter specifies
       if the file is to be opened for reading (``r''),  writing  (``w''),  or
       appending  (``a'') and, optionally, whether to override certain default
       aspects of library operation (see below).  When a file  is  opened  for
       appending,  existing data will not be touched; instead new data will be
       written as additional subfiles.  If an  existing  file  is  opened  for
       writing, all previous data is overwritten.

       If  a  file is opened for reading, the first TIFF directory in the file
       is automatically read (also  see  TIFFSetDirectory(3TIFF)  for  reading
       directories  other than the first).  If a file is opened for writing or
       appending, a default directory is  automatically  created  for  writing
       subsequent  data.   This directory has all the default values specified
       in TIFF Revision 6.0: BitsPerSample=1, ThreshHolding=bilevel art  scan,
       FillOrder=1  (most  significant bit of each data byte is filled first),
       Orientation=1 (the 0th row represents the visual top of the image,  and
       the  0th  column  represents  the  visual  left hand side), SamplesPer-
       Pixel=1, RowsPerStrip=infinity, ResolutionUnit=2 (inches), and Compres-
       sion=1  (no  compression).   To alter these values, or to define values
       for additional fields, TIFFSetField(3TIFF) must be used.

       TIFFFdOpen is like TIFFOpen except that it opens a TIFF file  given  an
       open file descriptor fd.  The file's name and mode must reflect that of
       the open descriptor.  The object associated with  the  file  descriptor
       must support random access.

       TIFFClientOpen  is like TIFFOpen except that the caller supplies a col-
       lection of functions that the library will  use  to  do  UNIX-like  I/O
       operations.   The  readproc  and writeproc are called to read and write
       data at the current file position.  seekproc is called  to  change  the
       current  file  position a la lseek(2).  closeproc is invoked to release
       any resources associated with an open file.   sizeproc  is  invoked  to
       obtain  the  size in bytes of a file.  mapproc and unmapproc are called
       to map and unmap a file's contents in memory; c.f.   mmap(2)  and  mun-
       map(2).  The clientdata parameter is an opaque ``handle'' passed to the
       client-specified routines passed as parameters to TIFFClientOpen.


       The open mode parameter can include the following flags in addition  to
       the ``r'', ``w'', and ``a'' flags.  Note however that option flags must
       follow the read-write-append specification.

       l      When creating a new file force information be written with  Lit-
              tle-Endian  byte  order (but see below).  By default the library
              will create new files using the native CPU byte order.

       b      When creating a new file force information be written with  Big-
              Endian  byte order (but see below).  By default the library will
              create new files using the native CPU byte order.

       L      Force image data that is read or written to be treated with bits
              filled  from Least Significant Bit (LSB) to Most Significant Bit
              (MSB).  Note that this is the opposite to the  way  the  library
              has worked from its inception.

       B      Force image data that is read or written to be treated with bits
              filled from Most Significant Bit (MSB) to Least Significant  Bit
              (LSB); this is the default.

       H      Force image data that is read or written to be treated with bits
              filled in the same order as the native CPU.

       M      Enable the use of memory-mapped files for  images  opened  read-
              only.   If  the underlying system does not support memory-mapped
              files or if the specific image being opened  cannot  be  memory-
              mapped then the library will fallback to using the normal system
              interface for reading information.  By default the library  will
              attempt to use memory-mapped files.

       m      Disable the use of memory-mapped files.

       C      Enable  the  use  of ``strip chopping'' when reading images that
              are comprised of a single strip or tile  of  uncompressed  data.
              Strip chopping is a mechanism by which the library will automat-
              ically convert the single-strip image to multiple  strips,  each
              of  which  has  about 8 Kilobytes of data.  This facility can be
              useful in reducing the amount of memory used to  read  an  image
              because  the  library normally reads each strip in its entirety.
              Strip chopping does however alter the apparent contents  of  the
              image  because  when an image is divided into multiple strips it
              looks as though the underlying file contains  multiple  separate
              strips.   Finally,  note that default handling of strip chopping
              is a compile-time configuration parameter.  The  default  behav-
              iour,  for backwards compatibility, is to enable strip chopping.

       c      Disable the use of strip chopping when reading images.

       h      Read TIFF header only, do not load the  first  image  directory.
              That  could  be useful in case of the broken first directory. We
              can open the file and proceed to the other directories.


       The TIFF specification (all versions)  states  that  compliant  readers
       must  be capable of reading images written in either byte order.  None-
       theless some software that claims to support the reading of TIFF images
       is  incapable  of  reading  images  in anything but the native CPU byte
       order on which the software was  written.   (Especially  notorious  are
       applications  written  to run on Intel-based machines.)  By default the
       library will create new files with the native byte-order of the CPU  on
       which  the application is run.  This ensures optimal performance and is
       portable to any application that conforms to  the  TIFF  specification.
       To  force  the library to use a specific byte-order when creating a new
       file the ``b'' and ``l'' option flags may be included in  the  call  to
       open a file; for example, ``wb'' or ``wl''.


       Upon  successful  completion  TIFFOpen,  TIFFFdOpen, and TIFFClientOpen
       return a TIFF pointer.  Otherwise, NULL is returned.


       All error messages are directed to the TIFFError(3TIFF) routine.  Like-
       wise,  warning messages are directed to the TIFFWarning(3TIFF) routine.

       "%s": Bad mode.  The specified mode parameter  was  not  one  of  ``r''
       (read), ``w'' (write), or ``a'' (append).

       %s:  Cannot open.  TIFFOpen() was unable to open the specified filename
       for read/writing.

       Cannot read TIFF header.  An error occurred while  attempting  to  read
       the header information.

       Error writing TIFF header.  An error occurred while writing the default
       header information for a new file.

       Not a TIFF file, bad magic number %d (0x%x).  The magic number  in  the
       header was not (hex) 0x4d4d or (hex) 0x4949.

       Not  a  TIFF  file, bad version number %d (0x%x).  The version field in
       the header was not 42 (decimal).

       Cannot append to file that has opposite byte ordering.  A file  with  a
       byte  ordering  opposite  to  the  native  byte ordering of the current
       machine was opened for appending (``a'').  This is a limitation of  the


       libtiff(3TIFF), TIFFClose(3TIFF)

libtiff                          July 1, 2005                  TIFFOpen(3TIFF)
See also TIFFClientOpen(3)
See also TIFFFdOpen(3)

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