Provided by: libtiff-dev_4.5.1+git230720-4ubuntu2.2_amd64 
NAME
TIFFOpen - open a TIFF file for reading or writing
SYNOPSIS
#include <tiffio.h>
TIFF *TIFFOpen(const char *filename, const char *mode)
TIFF *TIFFOpenW(const wchar_t *name, const char *mode)
TIFF *TIFFFdOpen(const int fd, const char *filename, const char *mode)
TIFF *TIFFOpenExt(const char *filename, const char *mode, TIFFOpenOptions *opts)
TIFF *TIFFOpenWExt(const wchar_t *name, const char *mode, TIFFOpenOptions *opts)
TIFF *TIFFFdOpenExt(const int fd, const char *filename, const char *mode, TIFFOpenOptions
*opts)
const char *TIFFSetFileName(TIFF *tif)
int TIFFSetFileno(TIFF *tif, int fd)
int TIFFSetMode(TIFF *tif, int 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)
TIFF *TIFFClientOpenExt(const char *filename, const char *mode, thandle_t clientdata,
TIFFReadWriteProc readproc, TIFFReadWriteProc writeproc, TIFFSeekProc seekproc,
TIFFCloseProc closeproc, TIFFSizeProc sizeproc, TIFFMapFileProc mapproc, TIFFUnmapFileProc
unmapproc, TIFFOpenOptions *opts)
thandle_t TIFFClientdata(TIFF *tif)
thandle_t TIFFSetClientdata(TIFF *tif, thandle_t newvalue)
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 NULL (0) is
returned. The mode parameter specifies if the file is to be opened for reading (r) or
(r+), writing (w), or appending (a) and, optionally, whether to override certain default
aspects of library operation (see below Options).
The mode (r) opens only an existing file for reading and (r+) for reading and writing.
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. 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 = ∞,
• ResolutionUnit = 2 (inches), and
• Compression = 1 (no compression).
To alter these values, or to define values for additional fields, TIFFSetField() must be
used.
TIFFOpenW() opens a TIFF file with a Unicode filename, for read/writing.
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. Even
for write-only mode, libtiff needs read permissions because some of its functions need to
read back the partially written TIFF file. The object associated with the file descriptor
must support random access. In order to close a TIFF file opened with TIFFFdOpen() first
TIFFCleanup() should be called to free the internal TIFF structure without closing the
file handle and afterwards the file should be closed using its file descriptor fd.
TIFFOpenExt() (added in libtiff 4.5) is like TIFFOpen(), but options, such as re-entrant
error and warning handlers and a limit in byte that libtiff internal memory allocation
functions are allowed to request per call may be passed with the opts argument. The opts
argument may be NULL. Refer to TIFFOpenOptions for allocating and filling the opts
argument parameters. The allocated memory for TIFFOpenOptions can be released straight
after successful execution of the related "TIFFOpenExt" functions.
TIFFOpenWExt() (added in libtiff 4.5) is like TIFFOpenExt(), but opens a TIFF file with a
Unicode filename.
TIFFFdOpenExt() (added in libtiff 4.5) is like TIFFFdOpen(), but options argument opts
like for TIFFOpenExt() can be passed.
TIFFSetFileName() sets the file name in the tif-structure and returns the old file name.
TIFFSetFileno() overwrites a copy of the open file's I/O descriptor, that was saved when
the TIFF file was first opened, and returns the previous value. See note below.
TIFFSetMode() sets the libtiff open mode in the tif-structure and returns the old mode.
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 functions are called to read and write data at the current file position.
seekproc is called to change the current file position à 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().
TIFFClientOpenExt() (added in libtiff 4.5) is like TIFFClientOpen(), but options argument
opts like for TIFFOpenExt() can be passed.
TIFFClientdata() returns open file's clientdata handle, which is the real open file's I/O
descriptor used by libtiff. Note: Within tif_unix.c this handle is converted into an
integer file descriptor.
TIFFSetClientdata() sets open file's clientdata, and return previous value. The
clientdata is used as open file's I/O descriptor within libtiff.
NOTE:
clientdata is used as file descriptor or handle of the opened TIFF file within libtif,
whereas the file descriptor fd (changeable by TIFFSetFileno()) is only set once to the
value of clientdata converted to an integer (in tif_win32.c as well as in tif_unix.c).
When updating the file's clientdata with TIFFSetClientdata(), the fd value is not
updated.
OPTIONS
The open mode parameter can include the following flags in addition to the r, r+, w, and a
flags. Note however that option flags must follow the read-write-append specification.
Note 2: Also for w the file will be opened with read access rights because libtiff needs
to read back the partially written TIFF file for some of its functions.
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.
4:
ClassicTIFF for creating a file (default)
8:
BigTIFF for creating a file.
D:
Enable use of deferred strip/tile offset/bytecount array loading. They will be loaded
the first time they are accessed to. This loading will be done in its entirety unless
the O flag is also specified.
O:
On-demand loading of values of the strip/tile offset/bytecount arrays, limited to the
requested strip/tile, instead of whole array loading (implies D)
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 TIFFErrorExtR() routine. Likewise, warning
messages are directed to the TIFFWarningExtR() 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), TIFFStrileQuery (3tiff), TIFFOpenOptions
AUTHOR
LibTIFF contributors
COPYRIGHT
1988-2024, LibTIFF contributors