TIFFOpen(3TIFF)                                                TIFFOpen(3TIFF)



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

SYNOPSIS
       #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)

DESCRIPTION
       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),
       SamplesPerPixel=1, RowsPerStrip=infinity, ResolutionUnit=2 (inches),
       and Compression=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
       collection 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
       munmap(2).  The clientdata parameter is an opaque ``handle'' passed to
       the client-specified routines passed as parameters to TIFFClientOpen.

OPTIONS
       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
              Little-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
              automatically 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
              behaviour, 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.

BYTE ORDER
       The TIFF specification (all versions) states that compliant readers
       must be capable of reading images written in either byte order.
       Nonetheless 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''.

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

DIAGNOSTICS
       All error messages are directed to the TIFFError(3TIFF) routine.
       Likewise, 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
       library.

SEE ALSO
       libtiff(3TIFF), TIFFClose(3TIFF)



libtiff                          July 1, 2005                  TIFFOpen(3TIFF)
