406 lines
13 KiB
HTML
406 lines
13 KiB
HTML
<!-- Creator : groff version 1.18.1 -->
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<!-- CreationDate: Sun Mar 6 13:59:51 2005 -->
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<html>
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<head>
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<meta name="generator" content="groff -Thtml, see www.gnu.org">
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<meta name="Content-Style" content="text/css">
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<title>TIFFOpen</title>
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</head>
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<body>
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<h1 align=center>TIFFOpen</h1>
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<a href="#NAME">NAME</a><br>
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<a href="#SYNOPSIS">SYNOPSIS</a><br>
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<a href="#DESCRIPTION">DESCRIPTION</a><br>
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<a href="#OPTIONS">OPTIONS</a><br>
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<a href="#BYTE ORDER">BYTE ORDER</a><br>
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<a href="#RETURN VALUES">RETURN VALUES</a><br>
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<a href="#DIAGNOSTICS">DIAGNOSTICS</a><br>
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<a href="#SEE ALSO">SEE ALSO</a><br>
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<hr>
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<a name="NAME"></a>
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<h2>NAME</h2>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="8%"></td>
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<td width="91%">
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<p>TIFFOpen, TIFFFdOpen, TIFFClientOpen − open a
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<small>TIFF</small> file for reading or writing</p>
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</td>
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</table>
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<a name="SYNOPSIS"></a>
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<h2>SYNOPSIS</h2>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<td width="8%"></td>
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<td width="91%">
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<p><b>#include <tiffio.h></b></p>
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<p><b>TIFF* TIFFOpen(const char *</b><i>filename</i><b>,
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const char *</b><i>mode</i><b>)<br>
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TIFF* TIFFFdOpen(const int</b> <i>fd</i><b>, const char
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*</b><i>filename</i><b>, const char
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*</b><i>mode</i><b>)</b></p>
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<p><b>typedef tsize_t (*TIFFReadWriteProc)(thandle_t,
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tdata_t, tsize_t);<br>
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typedef toff_t (*TIFFSeekProc)(thandle_t, toff_t, int);<br>
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typedef int (*TIFFCloseProc)(thandle_t);<br>
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typedef toff_t (*TIFFSizeProc)(thandle_t);<br>
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typedef int (*TIFFMapFileProc)(thandle_t, tdata_t*,
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toff_t*);<br>
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typedef void (*TIFFUnmapFileProc)(thandle_t, tdata_t,
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toff_t);</b></p>
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<p><b>TIFF* TIFFClientOpen(const char
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*</b><i>filename</i><b>, const char *</b><i>mode</i><b>,
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thandle_t</b> <i>clientdata</i><b>, TIFFReadWriteProc</b>
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<i>readproc</i><b>, TIFFReadWriteProc</b>
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<i>writeproc</i><b>, TIFFSeekProc</b> <i>seekproc</i><b>,
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TIFFCloseProc</b> <i>closeproc</i><b>, TIFFSizeProc</b>
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<i>sizeproc</i><b>, TIFFMapFileProc</b> <i>mapproc</i><b>,
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TIFFUnmapFileProc</b> <i>unmapproc</i><b>)</b></p>
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</td>
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</table>
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<a name="DESCRIPTION"></a>
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<h2>DESCRIPTION</h2>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<td width="8%"></td>
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<td width="91%">
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<p><i>TIFFOpen</i> opens a <small>TIFF</small> file whose
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name is <i>filename</i> and returns a handle to be used in
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subsequent calls to routines in <i>libtiff</i>. If the open
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operation fails, then zero is returned. The <i>mode</i>
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parameter specifies if the file is to be opened for reading
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(‘‘r’’), writing
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(‘‘w’’), or appending
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(‘‘a’’) and, optionally, whether to
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override certain default aspects of library operation (see
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below). When a file is opened for appending, existing data
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will not be touched; instead new data will be written as
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additional subfiles. If an existing file is opened for
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writing, all previous data is overwritten.</p>
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<p>If a file is opened for reading, the first
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<small>TIFF</small> directory in the file is automatically
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read (also see <i>TIFFSetDirectory</i>(3TIFF) for reading
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directories other than the first). If a file is opened for
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writing or appending, a default directory is automatically
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created for writing subsequent data. This directory has all
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the default values specified in <small>TIFF</small> Revision
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6.0: <i>BitsPerSample</i>=1, <i>ThreshHolding</i>=bilevel
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art scan, <i>FillOrder</i>=1 (most significant bit of each
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data byte is filled first), <i>Orientation</i>=1 (the 0th
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row represents the visual top of the image, and the 0th
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column represents the visual left hand side),
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<i>SamplesPerPixel</i>=1, <i>RowsPerStrip</i>=infinity,
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<i>ResolutionUnit</i>=2 (inches), and <i>Compression</i>=1
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(no compression). To alter these values, or to define values
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for additional fields, <i>TIFFSetField</i>(3TIFF) must be
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used.</p>
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<p><i>TIFFFdOpen</i> is like <i>TIFFOpen</i> except that it
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opens a <small>TIFF</small> file given an open file
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descriptor <i>fd</i>. The file’s name and mode must
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reflect that of the open descriptor. The object associated
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with the file descriptor <b>must support random
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access</b>.</p>
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<p><i>TIFFClientOpen</i> is like <i>TIFFOpen</i> except that
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the caller supplies a collection of functions that the
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library will use to do <small>UNIX</small> -like I/O
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operations. The <i>readproc</i> and <i>writeproc</i> are
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called to read and write data at the current file position.
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<i>seekproc</i> is called to change the current file
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position a la <i>lseek</i>(2). <i>closeproc</i> is invoked
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to release any resources associated with an open file.
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<i>sizeproc</i> is invoked to obtain the size in bytes of a
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file. <i>mapproc</i> and <i>unmapproc</i> are called to map
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and unmap a file’s contents in memory; c.f.
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<i>mmap</i>(2) and <i>munmap</i>(2). The <i>clientdata</i>
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parameter is an opaque ‘‘handle’’
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passed to the client-specified routines passed as parameters
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to <i>TIFFClientOpen</i>.</p>
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</td>
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</table>
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<a name="OPTIONS"></a>
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<h2>OPTIONS</h2>
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="8%"></td>
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<td width="91%">
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<p>The open mode parameter can include the following flags
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in addition to the ‘‘r’’,
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‘‘w’’, and
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‘‘a’’ flags. Note however that
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option flags must follow the read-write-append
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specification.</p>
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</td>
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</table>
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<!-- TABS -->
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<table width="100%" border=0 rules="none" frame="void"
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cols="5" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td>
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<td width="2%">
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<p><b>l</b></p>
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</td>
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<td width="6%"></td>
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<td width="80%">
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<p>When creating a new file force information be written
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with Little-Endian byte order (but see below). By default
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the library will create new files using the native
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<small>CPU</small> byte order.</p>
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</td>
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<td width="0%">
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</td>
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<tr valign="top" align="left">
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<td width="10%"></td>
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<td width="2%">
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<p><b>b</b></p>
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</td>
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<td width="6%"></td>
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<td width="80%">
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<p>When creating a new file force information be written
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with Big-Endian byte order (but see below). By default the
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library will create new files using the native
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<small>CPU</small> byte order.</p>
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</td>
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<td width="0%">
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</td>
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<tr valign="top" align="left">
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<td width="10%"></td>
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<td width="2%">
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<p><b>L</b></p>
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</td>
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<td width="6%"></td>
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<td width="80%">
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<p>Force image data that is read or written to be treated
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with bits filled from Least Significant Bit (
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<small>LSB</small> ) to Most Significant Bit (
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<small>MSB</small> ). Note that this is the opposite to the
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way the library has worked from its inception.</p>
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</td>
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<td width="0%">
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</td>
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<tr valign="top" align="left">
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<td width="10%"></td>
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<td width="2%">
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<p><b>B</b></p>
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</td>
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<td width="6%"></td>
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<td width="80%">
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<p>Force image data that is read or written to be treated
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with bits filled from Most Significant Bit (
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<small>MSB</small> ) to Least Significant Bit (
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<small>LSB</small> ); this is the default.</p>
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</td>
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<td width="0%">
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</td>
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<tr valign="top" align="left">
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<td width="10%"></td>
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<td width="2%">
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<p><b>H</b></p>
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</td>
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<td width="6%"></td>
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<td width="80%">
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<p>Force image data that is read or written to be treated
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with bits filled in the same order as the native
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<small>CPU.</small></p>
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</td>
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<td width="0%">
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</td>
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<tr valign="top" align="left">
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<td width="10%"></td>
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<td width="2%">
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<p><b>M</b></p>
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</td>
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<td width="6%"></td>
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<td width="80%">
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<p>Enable the use of memory-mapped files for images opened
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read-only. If the underlying system does not support
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memory-mapped files or if the specific image being opened
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cannot be memory-mapped then the library will fallback to
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using the normal system interface for reading information.
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By default the library will attempt to use memory-mapped
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files.</p>
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</td>
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<td width="0%">
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</td>
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<tr valign="top" align="left">
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<td width="10%"></td>
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<td width="2%">
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<p><b>m</b></p>
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</td>
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<td width="6%"></td>
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<td width="80%">
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<p>Disable the use of memory-mapped files.</p>
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</td>
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<td width="0%">
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</td>
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<tr valign="top" align="left">
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<td width="10%"></td>
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<td width="2%">
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<p><b>C</b></p>
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</td>
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<td width="6%"></td>
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<td width="80%">
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<p>Enable the use of ‘‘strip
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chopping’’ when reading images that are
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comprised of a single strip or tile of uncompressed data.
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Strip chopping is a mechanism by which the library will
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automatically convert the single-strip image to multiple
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strips, each of which has about 8 Kilobytes of data. This
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facility can be useful in reducing the amount of memory used
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to read an image because the library normally reads each
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strip in its entirety. Strip chopping does however alter the
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apparent contents of the image because when an image is
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divided into multiple strips it looks as though the
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underlying file contains multiple separate strips. Finally,
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note that default handling of strip chopping is a
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compile-time configuration parameter. The default behaviour,
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for backwards compatibility, is to enable strip
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chopping.</p>
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</td>
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<td width="0%">
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</td>
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<tr valign="top" align="left">
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<td width="10%"></td>
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<td width="2%">
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<p><b>c</b></p>
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</td>
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<td width="6%"></td>
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<td width="80%">
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<p>Disable the use of strip chopping when reading
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images.</p>
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</td>
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<td width="0%">
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</td>
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</table>
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<a name="BYTE ORDER"></a>
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<h2>BYTE ORDER</h2>
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<!-- INDENTATION -->
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="8%"></td>
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<td width="91%">
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<p>The <small>TIFF</small> specification (<b>all
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versions</b>) states that compliant readers <i>must be
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capable of reading images written in either byte order</i>.
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Nonetheless some software that claims to support the reading
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of <small>TIFF</small> images is incapable of reading images
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in anything but the native <small>CPU</small> byte order on
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which the software was written. (Especially notorious are
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applications written to run on Intel-based machines.) By
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default the library will create new files with the native
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byte-order of the <small>CPU</small> on which the
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application is run. This ensures optimal performance and is
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portable to any application that conforms to the TIFF
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specification. To force the library to use a specific
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byte-order when creating a new file the
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‘‘b’’ and
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‘‘l’’ option flags may be included
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in the call to open a file; for example,
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‘‘wb’’ or
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‘‘wl’’.</p>
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</td>
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</table>
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<a name="RETURN VALUES"></a>
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<h2>RETURN VALUES</h2>
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<!-- INDENTATION -->
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="8%"></td>
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<td width="91%">
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<p>Upon successful completion <i>TIFFOpen</i>,
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<i>TIFFFdOpen</i>, and <i>TIFFClientOpen</i> return a
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<small>TIFF</small> pointer. Otherwise, NULL is
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returned.</p>
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</td>
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</table>
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<a name="DIAGNOSTICS"></a>
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<h2>DIAGNOSTICS</h2>
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<!-- INDENTATION -->
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="8%"></td>
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<td width="91%">
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<p>All error messages are directed to the
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<i>TIFFError</i>(3TIFF) routine. Likewise, warning messages
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are directed to the <i>TIFFWarning</i>(3TIFF) routine.</p>
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<!-- INDENTATION -->
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<p><b>"%s": Bad mode</b>. The specified
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<i>mode</i> parameter was not one of
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‘‘r’’ (read),
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‘‘w’’ (write), or
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‘‘a’’ (append).</p>
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<!-- INDENTATION -->
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<p><b>%s: Cannot open</b>. <i>TIFFOpen</i>() was unable to
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open the specified filename for read/writing.</p>
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<!-- INDENTATION -->
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<p><b>Cannot read TIFF header</b>. An error occurred while
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attempting to read the header information.</p>
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<!-- INDENTATION -->
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<p><b>Error writing TIFF header</b>. An error occurred while
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writing the default header information for a new file.</p>
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<!-- INDENTATION -->
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<p><b>Not a TIFF file, bad magic number %d (0x%x)</b>. The
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magic number in the header was not (hex) 0x4d4d or (hex)
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0x4949.</p>
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<!-- INDENTATION -->
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<p><b>Not a TIFF file, bad version number %d (0x%x)</b>. The
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version field in the header was not 42 (decimal).</p>
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<!-- INDENTATION -->
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<p><b>Cannot append to file that has opposite byte
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ordering</b>. A file with a byte ordering opposite to the
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native byte ordering of the current machine was opened for
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appending (‘‘a’’). This is a
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limitation of the library.</p>
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</td>
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</table>
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<a name="SEE ALSO"></a>
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<h2>SEE ALSO</h2>
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<!-- INDENTATION -->
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="8%"></td>
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<td width="91%">
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<p><i>libtiff</i>(3TIFF), <i>TIFFClose</i>(3TIFF)</p>
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</td>
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</table>
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<hr>
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</body>
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</html>
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