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.