TIFFOPEN(3tiff) LibTIFF TIFFOPEN(3tiff)
NAME
TIFFOpen - open a TIFF file for reading or writing
SYNOPSIS
#include <tiffio.h>
TIFFOpen(3) 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:
o BitsPerSample = 1,
o ThreshHolding = "bilevel art scan"
o FillOrder = 1 (most significant bit of each data byte is filled
first)
o Orientation = 1 (the 0th row represents the visual top of the image,
and the 0th column represents the visual left hand side),
o SamplesPerPixel = 1,
o RowsPerStrip = <infinity>,
o ResolutionUnit = 2 (inches), and
o 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 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, such as re-entrant error and warning handlers may be passed
with the opts argument. The opts argument may be NULL. Refer to
TIFFOpenOptions for filling the opts argument.
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 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().
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, TIFFOpenOptions
AUTHOR
LibTIFF contributors
COPYRIGHT
1988-2022, LibTIFF contributors
4.6 October 9, 2023 TIFFOPEN(3tiff)
tiff 4.6.0 - Generated Thu Oct 12 05:52:43 CDT 2023