src/tiff/html/man/TIFFReadScanline.3tiff.html

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   7 <title>TIFFReadScanline</title>
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  10
  11 <h1 align=center>TIFFReadScanline</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="#NOTES">NOTES</a><br>
  16 <a href="#RETURN VALUES">RETURN VALUES</a><br>
  17 <a href="#DIAGNOSTICS">DIAGNOSTICS</a><br>
  18 <a href="#BUGS">BUGS</a><br>
  19 <a href="#SEE ALSO">SEE ALSO</a><br>
  20
  21 <hr>
  22 <a name="NAME"></a>
  23 <h2>NAME</h2>
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  30 <p>TIFFReadScanline &minus; read and decode a scanline of
  31 data from an open <small>TIFF</small> file</p>
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  33 </table>
  34 <a name="SYNOPSIS"></a>
  35 <h2>SYNOPSIS</h2>
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  42 <p><b>#include &lt;tiffio.h&gt;</b></p>
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  44 <p><b>int TIFFReadScanline(TIFF *</b><i>tif</i><b>,
  45 tdata_t</b> <i>buf</i><b>, uint32</b> <i>row</i><b>,
  46 tsample_t</b> <i>sample</i><b>)</b></p>
  47 </td>
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  49 <a name="DESCRIPTION"></a>
  50 <h2>DESCRIPTION</h2>
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  57 <p>Read the data for the specified row into the (user
  58 supplied) data buffer <i>buf</i>. The data are returned
  59 decompressed and, in the native byte- and bit-ordering, but
  60 are otherwise packed (see further below). The buffer must be
  61 large enough to hold an entire scanline of data.
  62 Applications should call the routine <i>TIFFScanlineSize</i>
  63 to find out the size (in bytes) of a scanline buffer. The
  64 <i>row</i> parameter is always used by
  65 <i>TIFFReadScanline</i>; the <i>sample</i> parameter is used
  66 only if data are organized in separate planes
  67 (<i>PlanarConfiguration</i>=2).</p>
  68 </td>
  69 </table>
  70 <a name="NOTES"></a>
  71 <h2>NOTES</h2>
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  78 <p>The library attempts to hide bit- and byte-ordering
  79 differences between the image and the native machine by
  80 converting data to the native machine order. Bit reversal is
  81 done if the <i>FillOrder</i> tag is opposite to the native
  82 machine bit order. 16- and 32-bit samples are automatically
  83 byte-swapped if the file was written with a byte order
  84 opposite to the native machine byte order,</p>
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  86 <p>In C++ the <i>sample</i> parameter defaults to 0.</p>
  87 </td>
  88 </table>
  89 <a name="RETURN VALUES"></a>
  90 <h2>RETURN VALUES</h2>
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  97 <p><i>TIFFReadScanline</i> returns &minus;1 if it detects an
  98 error; otherwise 1 is returned.</p>
  99 </td>
 100 </table>
 101 <a name="DIAGNOSTICS"></a>
 102 <h2>DIAGNOSTICS</h2>
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 109 <p>All error messages are directed to the
 110 <i>TIFFError</i>(3TIFF) routine.</p>
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 112 <p><b>Compression algorithm does not support random
 113 access</b>. Data was requested in a non-sequential order
 114 from a file that uses a compression algorithm and that has
 115 <i>RowsPerStrip</i> greater than one. That is, data in the
 116 image is stored in a compressed form, and with multiple rows
 117 packed into a strip. In this case, the library does not
 118 support random access to the data. The data should either be
 119 accessed sequentially, or the file should be converted so
 120 that each strip is made up of one row of data.</p>
 121 </td>
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 123 <a name="BUGS"></a>
 124 <h2>BUGS</h2>
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 131 <p>Reading subsampled YCbCR data does not work correctly
 132 because, for <i>PlanarConfiguration</i>=2 the size of a
 133 scanline is not calculated on a per-sample basis, and for
 134 <i>PlanarConfiguration</i>=1 the library does not unpack the
 135 block-interleaved samples; use the strip- and tile-based
 136 interfaces to read these formats.</p>
 137 </td>
 138 </table>
 139 <a name="SEE ALSO"></a>
 140 <h2>SEE ALSO</h2>
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 147 <p><b>TIFFOpen</b>(3TIFF),
 148 <b>TIFFReadEncodedStrip</b>(3TIFF),
 149 <b>TIFFReadRawStrip</b>(3TIFF), <b>libtiff</b>(3TIFF)</p>
 150 <!-- INDENTATION -->
 151 <p>Libtiff library home page:
 152 <b>http://www.remotesensing.org/libtiff/</b></p>
 153 </td>
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