1TIFFOpen(3TIFF) TIFFOpen(3TIFF)
2
6 TIFFOpen, TIFFFdOpen, TIFFClientOpen - open a TIFF file for reading or
7 writing
8
10 #include <tiffio.h>
11 TIFF* TIFFOpen(const char *filename, const char *mode)
13 TIFF* TIFFFdOpen(const int fd, const char *filename, const char *mode)
14 typedef tsize_t (*TIFFReadWriteProc)(thandle_t, tdata_t, tsize_t);
16 typedef toff_t (*TIFFSeekProc)(thandle_t, toff_t, int);
17 typedef int (*TIFFCloseProc)(thandle_t);
18 typedef toff_t (*TIFFSizeProc)(thandle_t);
19 typedef int (*TIFFMapFileProc)(thandle_t, tdata_t*, toff_t*);
20 typedef void (*TIFFUnmapFileProc)(thandle_t, tdata_t, toff_t);
21 TIFF* TIFFClientOpen(const char *filename, const char *mode, thandle_t
23 clientdata, TIFFReadWriteProc readproc, TIFFReadWriteProc writeproc,
24 TIFFSeekProc seekproc, TIFFCloseProc closeproc, TIFFSizeProc sizeproc,
25 TIFFMapFileProc mapproc, TIFFUnmapFileProc unmapproc)
26
28 TIFFOpen opens a TIFF file whose name is filename and returns a handle
29 to be used in subsequent calls to routines in libtiff. If the open
30 operation fails, then zero is returned. The mode parameter specifies
31 if the file is to be opened for reading (``r''), writing (``w''), or
32 appending (``a'') and, optionally, whether to override certain default
33 aspects of library operation (see below). When a file is opened for
34 appending, existing data will not be touched; instead new data will be
35 written as additional subfiles. If an existing file is opened for
36 writing, all previous data is overwritten.
37 If a file is opened for reading, the first TIFF directory in the file
39 is automatically read (also see TIFFSetDirectory(3TIFF) for reading
40 directories other than the first). If a file is opened for writing or
41 appending, a default directory is automatically created for writing
42 subsequent data. This directory has all the default values specified
43 in TIFF Revision 6.0: BitsPerSample=1, ThreshHolding=bilevel art scan,
44 FillOrder=1 (most significant bit of each data byte is filled first),
45 Orientation=1 (the 0th row represents the visual top of the image, and
46 the 0th column represents the visual left hand side), SamplesPer‐
47 Pixel=1, RowsPerStrip=infinity, ResolutionUnit=2 (inches), and Compres‐
48 sion=1 (no compression). To alter these values, or to define values
49 for additional fields, TIFFSetField(3TIFF) must be used.
50 TIFFFdOpen is like TIFFOpen except that it opens a TIFF file given an
52 open file descriptor fd. The file's name and mode must reflect that of
53 the open descriptor. The object associated with the file descriptor
54 must support random access.
55 TIFFClientOpen is like TIFFOpen except that the caller supplies a col‐
57 lection of functions that the library will use to do UNIX-like I/O
58 operations. The readproc and writeproc are called to read and write
59 data at the current file position. seekproc is called to change the
60 current file position a la lseek(2). closeproc is invoked to release
61 any resources associated with an open file. sizeproc is invoked to
62 obtain the size in bytes of a file. mapproc and unmapproc are called
63 to map and unmap a file's contents in memory; c.f. mmap(2) and mun‐
64 map(2). The clientdata parameter is an opaque ``handle'' passed to the
65 client-specified routines passed as parameters to TIFFClientOpen.
66
68 The open mode parameter can include the following flags in addition to
69 the ``r'', ``w'', and ``a'' flags. Note however that option flags must
70 follow the read-write-append specification.
71 l When creating a new file force information be written with Lit‐
73 tle-Endian byte order (but see below). By default the library
74 will create new files using the native CPU byte order.
75 b When creating a new file force information be written with Big-
77 Endian byte order (but see below). By default the library will
78 create new files using the native CPU byte order.
79 L Force image data that is read or written to be treated with bits
81 filled from Least Significant Bit (LSB) to Most Significant Bit
82 (MSB). Note that this is the opposite to the way the library
83 has worked from its inception.
84 B Force image data that is read or written to be treated with bits
86 filled from Most Significant Bit (MSB) to Least Significant Bit
87 (LSB); this is the default.
88 H Force image data that is read or written to be treated with bits
90 filled in the same order as the native CPU.
91 M Enable the use of memory-mapped files for images opened read-
93 only. If the underlying system does not support memory-mapped
94 files or if the specific image being opened cannot be memory-
95 mapped then the library will fallback to using the normal system
96 interface for reading information. By default the library will
97 attempt to use memory-mapped files.
98 m Disable the use of memory-mapped files.
100 C Enable the use of ``strip chopping'' when reading images that
102 are comprised of a single strip or tile of uncompressed data.
103 Strip chopping is a mechanism by which the library will automat‐
104 ically convert the single-strip image to multiple strips, each
105 of which has about 8 Kilobytes of data. This facility can be
106 useful in reducing the amount of memory used to read an image
107 because the library normally reads each strip in its entirety.
108 Strip chopping does however alter the apparent contents of the
109 image because when an image is divided into multiple strips it
110 looks as though the underlying file contains multiple separate
111 strips. Finally, note that default handling of strip chopping
112 is a compile-time configuration parameter. The default behav‐
113 iour, for backwards compatibility, is to enable strip chopping.
114 c Disable the use of strip chopping when reading images.
116 h Read TIFF header only, do not load the first image directory.
118 That could be useful in case of the broken first directory. We
119 can open the file and proceed to the other directories.
120
122 The TIFF specification (all versions) states that compliant readers
123 must be capable of reading images written in either byte order. None‐
124 theless some software that claims to support the reading of TIFF images
125 is incapable of reading images in anything but the native CPU byte
126 order on which the software was written. (Especially notorious are
127 applications written to run on Intel-based machines.) By default the
128 library will create new files with the native byte-order of the CPU on
129 which the application is run. This ensures optimal performance and is
130 portable to any application that conforms to the TIFF specification.
131 To force the library to use a specific byte-order when creating a new
132 file the ``b'' and ``l'' option flags may be included in the call to
133 open a file; for example, ``wb'' or ``wl''.
134
136 Upon successful completion TIFFOpen, TIFFFdOpen, and TIFFClientOpen
137 return a TIFF pointer. Otherwise, NULL is returned.
138
140 All error messages are directed to the TIFFError(3TIFF) routine. Like‐
141 wise, warning messages are directed to the TIFFWarning(3TIFF) routine.
142 "%s": Bad mode. The specified mode parameter was not one of ``r''
144 (read), ``w'' (write), or ``a'' (append).
145 %s: Cannot open. TIFFOpen() was unable to open the specified filename
147 for read/writing.
148 Cannot read TIFF header. An error occurred while attempting to read
150 the header information.
151 Error writing TIFF header. An error occurred while writing the default
153 header information for a new file.
154 Not a TIFF file, bad magic number %d (0x%x). The magic number in the
156 header was not (hex) 0x4d4d or (hex) 0x4949.
157 Not a TIFF file, bad version number %d (0x%x). The version field in
159 the header was not 42 (decimal).
160 Cannot append to file that has opposite byte ordering. A file with a
162 byte ordering opposite to the native byte ordering of the current
163 machine was opened for appending (``a''). This is a limitation of the
164 library.
165
167 libtiff(3TIFF), TIFFClose(3TIFF)
168libtiff July 1, 2005 TIFFOpen(3TIFF)