135 lines
5.0 KiB
HTML
135 lines
5.0 KiB
HTML
<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>TIFFReadScanline</title>
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</head>
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<body>
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<h1 align=center>TIFFReadScanline</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="#NOTES">NOTES</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="#BUGS">BUGS</a><br>
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<a href="#SEE ALSO">SEE ALSO</a><br>
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<hr>
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<!-- Creator : groff version 1.17.2 -->
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<!-- CreationDate: Mon Dec 22 00:39:25 2003 -->
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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="10%"></td><td width="90%">
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TIFFReadScanline - read and decode a scanline of data from an open <small>TIFF</small> file</td></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="10%"></td><td width="90%">
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<b>#include <tiffio.h><br>
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int TIFFReadScanline(TIFF* tif, tdata_t buf, uint32 row,
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tsample_t sample)</b></td></table>
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<a name="DESCRIPTION"></a>
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<h2>DESCRIPTION</h2>
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cols="2" cellspacing="0" cellpadding="0">
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<td width="10%"></td><td width="90%">
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Read the data for the specified row into the (user supplied)
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data buffer <i>buf</i>. The data are returned decompressed
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and, in the native byte- and bit-ordering, but are otherwise
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packed (see further below). The buffer must be large enough
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to hold an entire scanline of data. Applications should call
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the routine <i>TIFFScanlineSize</i> to find out the size (in
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bytes) of a scanline buffer. The <i>row</i> parameter is
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always used by <i>TIFFReadScanline</i>; the <i>sample</i>
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parameter is used only if data are organized in separate
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planes (<i>PlanarConfiguration</i>=2).</td></table>
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<a name="NOTES"></a>
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<h2>NOTES</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="10%"></td><td width="90%">
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The library attempts to hide bit- and byte-ordering
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differences between the image and the native machine by
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converting data to the native machine order. Bit reversal is
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done if the <i>FillOrder</i> tag is opposite to the native
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machine bit order. 16- and 32-bit samples are automatically
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byte-swapped if the file was written with a byte order
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opposite to the native machine byte order,</td></table>
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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="10%"></td><td width="90%">
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In C++ the <i>sample</i> parameter defaults to
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0.</td></table>
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<a name="RETURN VALUES"></a>
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<h2>RETURN VALUES</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="10%"></td><td width="90%">
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<i>TIFFReadScanline</i> returns -1 if it detects an error;
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otherwise 1 is returned.</td></table>
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<a name="DIAGNOSTICS"></a>
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<h2>DIAGNOSTICS</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="10%"></td><td width="90%">
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All error messages are directed to the <i>TIFFError</i>(3T)
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routine.</td></table>
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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="10%"></td><td width="90%">
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<b>Compression algorithm does not support random access</b>.
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Data was requested in a non-sequential order from a file
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that uses a compression algorithm and that has
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<i>RowsPerStrip</i> greater than one. That is, data in the
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image is stored in a compressed form, and with multiple rows
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packed into a strip. In this case, the library does not
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support random access to the data. The data should either be
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accessed sequentially, or the file should be converted so
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that each strip is made up of one row of data.</td></table>
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<a name="BUGS"></a>
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<h2>BUGS</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="10%"></td><td width="90%">
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Reading subsampled YCbCR data does not work correctly
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because, for <i>PlanarConfiguration</i>=2 the size of a
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scanline is not calculated on a per-sample basis, and for
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<i>PlanarConfiguration</i>=1 the library does not unpack the
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block-interleaved samples; use the strip- and tile-based
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interfaces to read these formats.</td></table>
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<a name="SEE ALSO"></a>
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<h2>SEE ALSO</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="10%"></td><td width="90%">
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<i>libtiff</i>(3T), <i>TIFFOpen</i>(3T),
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<i>TIFFReadEncodedStrip</i>(3T),
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<i>TIFFReadRawStrip</i>(3T)</td></table>
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<hr>
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</body>
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</html>
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