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TIFFOpen(3T)									     TIFFOpen(3T)

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

       #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 sub-
       sequent 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(3T) 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 signifi-
       cant 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), Sam-
       plesPerPixel=1, RowsPerStrip=infinity, ResolutionUnit=2 (inches),  and  Compression=1  (no
       compression).   To alter these values, or to define values for additional fields, TIFFSet-
       Field(3T) 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 asso-
       ciated 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.

       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  speci-

       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  oppo-
	      site 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 underly-
	      ing 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 reduc-
	      ing  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  con-
	      tents  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.

       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 appli-
       cations 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  specifi-
       cation.	 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(3T) routine.  Likewise, warning  messages
       are directed to the TIFFWarning(3T) 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  informa-

       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

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

       libtiff(3T), TIFFClose(3T)

					 January 9, 1996			     TIFFOpen(3T)
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