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

Provided by: libtiff5-dev_4.0.9-5ubuntu0.10_amd64

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.