source: trunk/src/3rdparty/libtiff/html/man/TIFFOpen.3tiff.html

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1<!-- Creator : groff version 1.18.1 -->
2<!-- CreationDate: Fri Jul 13 17:43:15 2007 -->
3<html>
4<head>
5<meta name="generator" content="groff -Thtml, see www.gnu.org">
6<meta name="Content-Style" content="text/css">
7<title>TIFFOpen</title>
8</head>
9<body>
10
11<h1 align=center>TIFFOpen</h1>
12<a href="#NAME">NAME</a><br>
13<a href="#SYNOPSIS">SYNOPSIS</a><br>
14<a href="#DESCRIPTION">DESCRIPTION</a><br>
15<a href="#OPTIONS">OPTIONS</a><br>
16<a href="#BYTE ORDER">BYTE ORDER</a><br>
17<a href="#RETURN VALUES">RETURN VALUES</a><br>
18<a href="#DIAGNOSTICS">DIAGNOSTICS</a><br>
19<a href="#SEE ALSO">SEE ALSO</a><br>
20
21<hr>
22<a name="NAME"></a>
23<h2>NAME</h2>
24<!-- INDENTATION -->
25<table width="100%" border=0 rules="none" frame="void"
26 cols="2" cellspacing="0" cellpadding="0">
27<tr valign="top" align="left">
28<td width="8%"></td>
29<td width="91%">
30<p>TIFFOpen, TIFFFdOpen, TIFFClientOpen &minus; open a
31<small>TIFF</small> file for reading or writing</p>
32</td>
33</table>
34<a name="SYNOPSIS"></a>
35<h2>SYNOPSIS</h2>
36<!-- INDENTATION -->
37<table width="100%" border=0 rules="none" frame="void"
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41<td width="91%">
42<p><b>#include &lt;tiffio.h&gt;</b></p>
43<!-- INDENTATION -->
44<p><b>TIFF* TIFFOpen(const char *</b><i>filename</i><b>,
45const char *</b><i>mode</i><b>)<br>
46TIFF* TIFFFdOpen(const int</b> <i>fd</i><b>, const char
47*</b><i>filename</i><b>, const char
48*</b><i>mode</i><b>)</b></p>
49<!-- INDENTATION -->
50<p><b>typedef tsize_t (*TIFFReadWriteProc)(thandle_t,
51tdata_t, tsize_t);<br>
52typedef toff_t (*TIFFSeekProc)(thandle_t, toff_t, int);<br>
53typedef int (*TIFFCloseProc)(thandle_t);<br>
54typedef toff_t (*TIFFSizeProc)(thandle_t);<br>
55typedef int (*TIFFMapFileProc)(thandle_t, tdata_t*,
56toff_t*);<br>
57typedef void (*TIFFUnmapFileProc)(thandle_t, tdata_t,
58toff_t);</b></p>
59<!-- INDENTATION -->
60<p><b>TIFF* TIFFClientOpen(const char
61*</b><i>filename</i><b>, const char *</b><i>mode</i><b>,
62thandle_t</b> <i>clientdata</i><b>, TIFFReadWriteProc</b>
63<i>readproc</i><b>, TIFFReadWriteProc</b>
64<i>writeproc</i><b>, TIFFSeekProc</b> <i>seekproc</i><b>,
65TIFFCloseProc</b> <i>closeproc</i><b>, TIFFSizeProc</b>
66<i>sizeproc</i><b>, TIFFMapFileProc</b> <i>mapproc</i><b>,
67TIFFUnmapFileProc</b> <i>unmapproc</i><b>)</b></p>
68</td>
69</table>
70<a name="DESCRIPTION"></a>
71<h2>DESCRIPTION</h2>
72<!-- INDENTATION -->
73<table width="100%" border=0 rules="none" frame="void"
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77<td width="91%">
78<p><i>TIFFOpen</i> opens a <small>TIFF</small> file whose
79name is <i>filename</i> and returns a handle to be used in
80subsequent calls to routines in <i>libtiff</i>. If the open
81operation fails, then zero is returned. The <i>mode</i>
82parameter specifies if the file is to be opened for reading
83(&lsquo;&lsquo;r&rsquo;&rsquo;), writing
84(&lsquo;&lsquo;w&rsquo;&rsquo;), or appending
85(&lsquo;&lsquo;a&rsquo;&rsquo;) and, optionally, whether to
86override certain default aspects of library operation (see
87below). When a file is opened for appending, existing data
88will not be touched; instead new data will be written as
89additional subfiles. If an existing file is opened for
90writing, all previous data is overwritten.</p>
91<!-- INDENTATION -->
92<p>If a file is opened for reading, the first
93<small>TIFF</small> directory in the file is automatically
94read (also see <i>TIFFSetDirectory</i>(3TIFF) for reading
95directories other than the first). If a file is opened for
96writing or appending, a default directory is automatically
97created for writing subsequent data. This directory has all
98the default values specified in <small>TIFF</small> Revision
996.0: <i>BitsPerSample</i>=1, <i>ThreshHolding</i>=bilevel
100art scan, <i>FillOrder</i>=1 (most significant bit of each
101data byte is filled first), <i>Orientation</i>=1 (the 0th
102row represents the visual top of the image, and the 0th
103column represents the visual left hand side),
104<i>SamplesPerPixel</i>=1, <i>RowsPerStrip</i>=infinity,
105<i>ResolutionUnit</i>=2 (inches), and <i>Compression</i>=1
106(no compression). To alter these values, or to define values
107for additional fields, <i>TIFFSetField</i>(3TIFF) must be
108used.</p>
109<!-- INDENTATION -->
110<p><i>TIFFFdOpen</i> is like <i>TIFFOpen</i> except that it
111opens a <small>TIFF</small> file given an open file
112descriptor <i>fd</i>. The file&rsquo;s name and mode must
113reflect that of the open descriptor. The object associated
114with the file descriptor <b>must support random
115access</b>.</p>
116<!-- INDENTATION -->
117<p><i>TIFFClientOpen</i> is like <i>TIFFOpen</i> except that
118the caller supplies a collection of functions that the
119library will use to do <small>UNIX</small> -like I/O
120operations. The <i>readproc</i> and <i>writeproc</i> are
121called to read and write data at the current file position.
122<i>seekproc</i> is called to change the current file
123position a la <i>lseek</i>(2). <i>closeproc</i> is invoked
124to release any resources associated with an open file.
125<i>sizeproc</i> is invoked to obtain the size in bytes of a
126file. <i>mapproc</i> and <i>unmapproc</i> are called to map
127and unmap a file&rsquo;s contents in memory; c.f.
128<i>mmap</i>(2) and <i>munmap</i>(2). The <i>clientdata</i>
129parameter is an opaque &lsquo;&lsquo;handle&rsquo;&rsquo;
130passed to the client-specified routines passed as parameters
131to <i>TIFFClientOpen</i>.</p>
132</td>
133</table>
134<a name="OPTIONS"></a>
135<h2>OPTIONS</h2>
136<!-- INDENTATION -->
137<table width="100%" border=0 rules="none" frame="void"
138 cols="2" cellspacing="0" cellpadding="0">
139<tr valign="top" align="left">
140<td width="8%"></td>
141<td width="91%">
142<p>The open mode parameter can include the following flags
143in addition to the &lsquo;&lsquo;r&rsquo;&rsquo;,
144&lsquo;&lsquo;w&rsquo;&rsquo;, and
145&lsquo;&lsquo;a&rsquo;&rsquo; flags. Note however that
146option flags must follow the read-write-append
147specification.</p>
148</td>
149</table>
150<!-- TABS -->
151<table width="100%" border=0 rules="none" frame="void"
152 cols="5" cellspacing="0" cellpadding="0">
153<tr valign="top" align="left">
154<td width="10%"></td>
155<td width="2%">
156
157<p><b>l</b></p>
158</td>
159<td width="6%"></td>
160<td width="80%">
161
162<p>When creating a new file force information be written
163with Little-Endian byte order (but see below). By default
164the library will create new files using the native
165<small>CPU</small> byte order.</p>
166</td>
167<td width="0%">
168</td>
169<tr valign="top" align="left">
170<td width="10%"></td>
171<td width="2%">
172
173<p><b>b</b></p>
174</td>
175<td width="6%"></td>
176<td width="80%">
177
178<p>When creating a new file force information be written
179with Big-Endian byte order (but see below). By default the
180library will create new files using the native
181<small>CPU</small> byte order.</p>
182</td>
183<td width="0%">
184</td>
185<tr valign="top" align="left">
186<td width="10%"></td>
187<td width="2%">
188
189<p><b>L</b></p>
190</td>
191<td width="6%"></td>
192<td width="80%">
193
194<p>Force image data that is read or written to be treated
195with bits filled from Least Significant Bit (
196<small>LSB</small> ) to Most Significant Bit (
197<small>MSB</small> ). Note that this is the opposite to the
198way the library has worked from its inception.</p>
199</td>
200<td width="0%">
201</td>
202<tr valign="top" align="left">
203<td width="10%"></td>
204<td width="2%">
205
206<p><b>B</b></p>
207</td>
208<td width="6%"></td>
209<td width="80%">
210
211<p>Force image data that is read or written to be treated
212with bits filled from Most Significant Bit (
213<small>MSB</small> ) to Least Significant Bit (
214<small>LSB</small> ); this is the default.</p>
215</td>
216<td width="0%">
217</td>
218<tr valign="top" align="left">
219<td width="10%"></td>
220<td width="2%">
221
222<p><b>H</b></p>
223</td>
224<td width="6%"></td>
225<td width="80%">
226
227<p>Force image data that is read or written to be treated
228with bits filled in the same order as the native
229<small>CPU.</small></p>
230</td>
231<td width="0%">
232</td>
233<tr valign="top" align="left">
234<td width="10%"></td>
235<td width="2%">
236
237<p><b>M</b></p>
238</td>
239<td width="6%"></td>
240<td width="80%">
241
242<p>Enable the use of memory-mapped files for images opened
243read-only. If the underlying system does not support
244memory-mapped files or if the specific image being opened
245cannot be memory-mapped then the library will fallback to
246using the normal system interface for reading information.
247By default the library will attempt to use memory-mapped
248files.</p>
249</td>
250<td width="0%">
251</td>
252<tr valign="top" align="left">
253<td width="10%"></td>
254<td width="2%">
255
256<p><b>m</b></p>
257</td>
258<td width="6%"></td>
259<td width="80%">
260
261<p>Disable the use of memory-mapped files.</p>
262</td>
263<td width="0%">
264</td>
265<tr valign="top" align="left">
266<td width="10%"></td>
267<td width="2%">
268
269<p><b>C</b></p>
270</td>
271<td width="6%"></td>
272<td width="80%">
273
274<p>Enable the use of &lsquo;&lsquo;strip
275chopping&rsquo;&rsquo; when reading images that are
276comprised of a single strip or tile of uncompressed data.
277Strip chopping is a mechanism by which the library will
278automatically convert the single-strip image to multiple
279strips, each of which has about 8 Kilobytes of data. This
280facility can be useful in reducing the amount of memory used
281to read an image because the library normally reads each
282strip in its entirety. Strip chopping does however alter the
283apparent contents of the image because when an image is
284divided into multiple strips it looks as though the
285underlying file contains multiple separate strips. Finally,
286note that default handling of strip chopping is a
287compile-time configuration parameter. The default behaviour,
288for backwards compatibility, is to enable strip
289chopping.</p>
290</td>
291<td width="0%">
292</td>
293<tr valign="top" align="left">
294<td width="10%"></td>
295<td width="2%">
296
297<p><b>c</b></p>
298</td>
299<td width="6%"></td>
300<td width="80%">
301
302<p>Disable the use of strip chopping when reading
303images.</p>
304</td>
305<td width="0%">
306</td>
307<tr valign="top" align="left">
308<td width="10%"></td>
309<td width="2%">
310
311<p><b>h</b></p>
312</td>
313<td width="6%"></td>
314<td width="80%">
315
316<p>Read TIFF header only, do not load the first image
317directory. That could be useful in case of the broken first
318directory. We can open the file and proceed to the other
319directories.</p>
320</td>
321<td width="0%">
322</td>
323</table>
324<a name="BYTE ORDER"></a>
325<h2>BYTE ORDER</h2>
326<!-- INDENTATION -->
327<table width="100%" border=0 rules="none" frame="void"
328 cols="2" cellspacing="0" cellpadding="0">
329<tr valign="top" align="left">
330<td width="8%"></td>
331<td width="91%">
332<p>The <small>TIFF</small> specification (<b>all
333versions</b>) states that compliant readers <i>must be
334capable of reading images written in either byte order</i>.
335Nonetheless some software that claims to support the reading
336of <small>TIFF</small> images is incapable of reading images
337in anything but the native <small>CPU</small> byte order on
338which the software was written. (Especially notorious are
339applications written to run on Intel-based machines.) By
340default the library will create new files with the native
341byte-order of the <small>CPU</small> on which the
342application is run. This ensures optimal performance and is
343portable to any application that conforms to the TIFF
344specification. To force the library to use a specific
345byte-order when creating a new file the
346&lsquo;&lsquo;b&rsquo;&rsquo; and
347&lsquo;&lsquo;l&rsquo;&rsquo; option flags may be included
348in the call to open a file; for example,
349&lsquo;&lsquo;wb&rsquo;&rsquo; or
350&lsquo;&lsquo;wl&rsquo;&rsquo;.</p>
351</td>
352</table>
353<a name="RETURN VALUES"></a>
354<h2>RETURN VALUES</h2>
355<!-- INDENTATION -->
356<table width="100%" border=0 rules="none" frame="void"
357 cols="2" cellspacing="0" cellpadding="0">
358<tr valign="top" align="left">
359<td width="8%"></td>
360<td width="91%">
361<p>Upon successful completion <i>TIFFOpen</i>,
362<i>TIFFFdOpen</i>, and <i>TIFFClientOpen</i> return a
363<small>TIFF</small> pointer. Otherwise, NULL is
364returned.</p>
365</td>
366</table>
367<a name="DIAGNOSTICS"></a>
368<h2>DIAGNOSTICS</h2>
369<!-- INDENTATION -->
370<table width="100%" border=0 rules="none" frame="void"
371 cols="2" cellspacing="0" cellpadding="0">
372<tr valign="top" align="left">
373<td width="8%"></td>
374<td width="91%">
375<p>All error messages are directed to the
376<i>TIFFError</i>(3TIFF) routine. Likewise, warning messages
377are directed to the <i>TIFFWarning</i>(3TIFF) routine.</p>
378<!-- INDENTATION -->
379<p><b>&quot;%s&quot;: Bad mode</b>. The specified
380<i>mode</i> parameter was not one of
381&lsquo;&lsquo;r&rsquo;&rsquo; (read),
382&lsquo;&lsquo;w&rsquo;&rsquo; (write), or
383&lsquo;&lsquo;a&rsquo;&rsquo; (append).</p>
384<!-- INDENTATION -->
385<p><b>%s: Cannot open</b>. <i>TIFFOpen</i>() was unable to
386open the specified filename for read/writing.</p>
387<!-- INDENTATION -->
388<p><b>Cannot read TIFF header</b>. An error occurred while
389attempting to read the header information.</p>
390<!-- INDENTATION -->
391<p><b>Error writing TIFF header</b>. An error occurred while
392writing the default header information for a new file.</p>
393<!-- INDENTATION -->
394<p><b>Not a TIFF file, bad magic number %d (0x%x)</b>. The
395magic number in the header was not (hex) 0x4d4d or (hex)
3960x4949.</p>
397<!-- INDENTATION -->
398<p><b>Not a TIFF file, bad version number %d (0x%x)</b>. The
399version field in the header was not 42 (decimal).</p>
400<!-- INDENTATION -->
401<p><b>Cannot append to file that has opposite byte
402ordering</b>. A file with a byte ordering opposite to the
403native byte ordering of the current machine was opened for
404appending (&lsquo;&lsquo;a&rsquo;&rsquo;). This is a
405limitation of the library.</p>
406</td>
407</table>
408<a name="SEE ALSO"></a>
409<h2>SEE ALSO</h2>
410<!-- INDENTATION -->
411<table width="100%" border=0 rules="none" frame="void"
412 cols="2" cellspacing="0" cellpadding="0">
413<tr valign="top" align="left">
414<td width="8%"></td>
415<td width="91%">
416<p><i>libtiff</i>(3TIFF), <i>TIFFClose</i>(3TIFF)</p>
417</td>
418</table>
419<hr>
420</body>
421</html>
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