TIFFOpen(3tiff)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)
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 read‐
ing ("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.
If a file is opened for reading, the first TIFF directory in the file
is automatically read. See also TIFFSetDirectory(3tiff) for information
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 val‐
ues 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)
· Compression=1 (no compression)
To alter these values, or to define values for additional fields, TIFF‐
SetField(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 col‐
lection of functions that the library uses to perform UNIX-like I/O
operations:
· readproc and writeproc are called to read and write data at the
current file position.
· seekproc is called to change the current file position. See also
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 the contents of
a file in memory. See also mmap(2) and munmap(2).
· The clientdata parameter is an opaque "handle" passed to the
client-specified routines that are passed as parameters to TIFF‐
ClientOpen.
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 cre‐
ates 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. Like‐
wise, 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 magThenumagic%dnumber).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 thAt fileopwithteabybyterordering opposite to the
native byte ordering of the current machine was
opened for appending ("a"). This is a limita‐
tion of the library.
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 section 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 underly‐
ing file contains multiple separate strips.
Finally, note that default handling of strip
chopping is a compile-time configuration param‐
eter. The default behaviour, for backwards com‐
patibility, 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 sys‐
tem interface for reading information. By
default, the library attempts to use memory-
mapped files.
m Disable the use of memory-mapped files.
Upon successful completion, TIFFOpen, TIFFFdOpen, and TIFFClientOpen
return a TIFF pointer. Otherwise, NULL is returned.
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Availability │image/library/libtiff │
├─────────────────────────────┼─────────────────────────────┤
│Interface stability │Uncommitted │
└─────────────────────────────┴─────────────────────────────┘
libtiff(3), TIFFClose(3tiff)
This man page was originally written by Sam Leffler. Updated by Breda
McColgan, Sun Microsystems Inc., 2004.
05 Apr 2004 TIFFOpen(3tiff)
