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2 <!-- CreationDate: Mon Mar 13 18:03:10 2006 --> |
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5 <meta name="generator" content="groff -Thtml, see www.gnu.org"> |
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6 <meta name="Content-Style" content="text/css"> |
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7 <title>TIFFReadScanline</title> |
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8 </head> |
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9 <body> |
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10 |
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11 <h1 align=center>TIFFReadScanline</h1> |
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12 <a href="#NAME">NAME</a><br> |
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13 <a href="#SYNOPSIS">SYNOPSIS</a><br> |
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14 <a href="#DESCRIPTION">DESCRIPTION</a><br> |
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15 <a href="#NOTES">NOTES</a><br> |
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16 <a href="#RETURN VALUES">RETURN VALUES</a><br> |
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17 <a href="#DIAGNOSTICS">DIAGNOSTICS</a><br> |
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18 <a href="#BUGS">BUGS</a><br> |
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19 <a href="#SEE ALSO">SEE ALSO</a><br> |
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20 |
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21 <hr> |
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22 <a name="NAME"></a> |
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23 <h2>NAME</h2> |
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29 <td width="91%"> |
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30 <p>TIFFReadScanline − read and decode a scanline of |
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31 data from an open <small>TIFF</small> file</p> |
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32 </td> |
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33 </table> |
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34 <a name="SYNOPSIS"></a> |
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35 <h2>SYNOPSIS</h2> |
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42 <p><b>#include <tiffio.h></b></p> |
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43 <!-- INDENTATION --> |
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44 <p><b>int TIFFReadScanline(TIFF *</b><i>tif</i><b>, |
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45 tdata_t</b> <i>buf</i><b>, uint32</b> <i>row</i><b>, |
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46 tsample_t</b> <i>sample</i><b>)</b></p> |
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47 </td> |
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48 </table> |
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49 <a name="DESCRIPTION"></a> |
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50 <h2>DESCRIPTION</h2> |
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57 <p>Read the data for the specified row into the (user |
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58 supplied) data buffer <i>buf</i>. The data are returned |
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59 decompressed and, in the native byte- and bit-ordering, but |
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60 are otherwise packed (see further below). The buffer must be |
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61 large enough to hold an entire scanline of data. |
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62 Applications should call the routine <i>TIFFScanlineSize</i> |
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63 to find out the size (in bytes) of a scanline buffer. The |
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64 <i>row</i> parameter is always used by |
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65 <i>TIFFReadScanline</i>; the <i>sample</i> parameter is used |
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66 only if data are organized in separate planes |
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67 (<i>PlanarConfiguration</i>=2).</p> |
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68 </td> |
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69 </table> |
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70 <a name="NOTES"></a> |
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71 <h2>NOTES</h2> |
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78 <p>The library attempts to hide bit- and byte-ordering |
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79 differences between the image and the native machine by |
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80 converting data to the native machine order. Bit reversal is |
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81 done if the <i>FillOrder</i> tag is opposite to the native |
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82 machine bit order. 16- and 32-bit samples are automatically |
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83 byte-swapped if the file was written with a byte order |
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84 opposite to the native machine byte order,</p> |
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85 <!-- INDENTATION --> |
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86 <p>In C++ the <i>sample</i> parameter defaults to 0.</p> |
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87 </td> |
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88 </table> |
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89 <a name="RETURN VALUES"></a> |
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90 <h2>RETURN VALUES</h2> |
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91 <!-- INDENTATION --> |
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95 <td width="8%"></td> |
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96 <td width="91%"> |
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97 <p><i>TIFFReadScanline</i> returns −1 if it detects an |
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98 error; otherwise 1 is returned.</p> |
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99 </td> |
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100 </table> |
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101 <a name="DIAGNOSTICS"></a> |
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102 <h2>DIAGNOSTICS</h2> |
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109 <p>All error messages are directed to the |
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110 <i>TIFFError</i>(3TIFF) routine.</p> |
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111 <!-- INDENTATION --> |
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112 <p><b>Compression algorithm does not support random |
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113 access</b>. Data was requested in a non-sequential order |
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114 from a file that uses a compression algorithm and that has |
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115 <i>RowsPerStrip</i> greater than one. That is, data in the |
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116 image is stored in a compressed form, and with multiple rows |
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117 packed into a strip. In this case, the library does not |
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118 support random access to the data. The data should either be |
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119 accessed sequentially, or the file should be converted so |
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120 that each strip is made up of one row of data.</p> |
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121 </td> |
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122 </table> |
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123 <a name="BUGS"></a> |
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124 <h2>BUGS</h2> |
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125 <!-- INDENTATION --> |
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131 <p>Reading subsampled YCbCR data does not work correctly |
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132 because, for <i>PlanarConfiguration</i>=2 the size of a |
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133 scanline is not calculated on a per-sample basis, and for |
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134 <i>PlanarConfiguration</i>=1 the library does not unpack the |
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135 block-interleaved samples; use the strip- and tile-based |
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136 interfaces to read these formats.</p> |
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137 </td> |
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138 </table> |
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139 <a name="SEE ALSO"></a> |
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140 <h2>SEE ALSO</h2> |
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141 <!-- INDENTATION --> |
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145 <td width="8%"></td> |
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146 <td width="91%"> |
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147 <p><b>TIFFOpen</b>(3TIFF), |
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148 <b>TIFFReadEncodedStrip</b>(3TIFF), |
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149 <b>TIFFReadRawStrip</b>(3TIFF), <b>libtiff</b>(3TIFF)</p> |
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150 <!-- INDENTATION --> |
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151 <p>Libtiff library home page: |
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152 <b>http://www.remotesensing.org/libtiff/</b></p> |
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153 </td> |
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154 </table> |
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155 <hr> |
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156 </body> |
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157 </html> |