TIFFOpen(3tiff) Introduction to Library Functions TIFFOpen(3tiff)
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 whether 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 is not touched.
Instead, new data is written as additional subfiles. If an existing file is opened for writing, all previous data is overwritten.
EXTENDED DESCRIPTION
If a file is opened for reading, the first TIFF directory in the file is automatically read. See also TIFFSetDirectory(3tiff) for informa-
tion on how to read 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 of 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)
o 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 TIFFFdOpen opens a TIFF file given an open file descriptor fd. The file 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 uses to perform UNIX-like I/O
operations:
o readproc and writeproc are called to read and write data at the current file position.
o seekproc is called to change the current file position. See also lseek(2).
o closeproc is invoked to release any resources associated with an open file.
o sizeproc is invoked to obtain the size in bytes of a file.
o mapproc and unmapproc are called to map and unmap the contents of a file in memory. See also mmap(2) and munmap(2).
o The clientdata parameter is an opaque "handle" passed to the client-specified routines that are passed as parameters to TIFFClien-
tOpen.
Byte Order
The TIFF specification (all versions) states that compliant readers must be capable of reading images written in either byte order. How-
ever, 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. By default, the library creates 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".
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 is not one of "r" (read), "w" (write), or "a" (append).
%s: Cannot open. TIFFOpen() is unable to open the specified filename for reading or writing.
Cannot read TIFF header.An error occurred while attempting to read the header information.
Error writing TIFF headeAn error occurred while writing the default header information for a new file.
Not a TIFF file, bad magThenmagic number%in.the header was not (hex) 0x4d4d or (hex) 0x4949.
Not a TIFF file, bad verThenversion fieldxin)the header was not 42 (decimal).
Cannot append to file thAtfile withsatbytetorderingnopposite to the native byte ordering of the current machine was opened for appending
("a"). This is a limitation of the library.
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.
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.
b When creating a new file, force information to be written with Big-Endian byte order (but see the Byte Order sec-
tion of this reference page). By default, the library creates new files using the native CPU byte order.
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 automatically converts 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, the image 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 Force image data that is read or written to be treated with bits filled in the same order as the native CPU.
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 that the library has worked from its inception.
l When creating a new file, force information to be written with Little-Endian byte order (but see the Byte Order
section of this reference page). By default, the library creates new files using the native CPU byte order.
M Enable the use of memory-mapped files for images opened as read-only. If the underlying system does not support
memory-mapped files, or if the specific image being opened cannot be memory-mapped, the library uses the normal
system interface for reading information. By default, the library attempts to use memory-mapped files.
m Disable the use of memory-mapped files.
RETURN VALUES
Upon successful completion, TIFFOpen, TIFFFdOpen, and TIFFClientOpen return a TIFF pointer. Otherwise, NULL is returned.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWTiff |
+-----------------------------+-----------------------------+
|Interface stability |External |
+-----------------------------+-----------------------------+
SEE ALSO
libtiff(3), TIFFClose(3tiff)
NOTES
This man page was originally written by Sam Leffler. Updated by Breda McColgan, Sun Microsystems Inc., 2004.
SunOS 5.10 05 Apr 2004 TIFFOpen(3tiff)