src/tiff/html/man/TIFFReadRGBATile.3tiff.html

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   7 <title>TIFFReadRGBATile</title>
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  10
  11 <h1 align=center>TIFFReadRGBATile</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="#SEE ALSO">SEE ALSO</a><br>
  19
  20 <hr>
  21 <a name="NAME"></a>
  22 <h2>NAME</h2>
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  29 <p>TIFFReadRGBATile &minus; read and decode an image tile
  30 into a fixed-format raster</p>
  31 </td>
  32 </table>
  33 <a name="SYNOPSIS"></a>
  34 <h2>SYNOPSIS</h2>
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  41 <p><b>#include &lt;tiffio.h&gt;</b></p>
  42 </td>
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  50
  51 <p><b>#define TIFFGetR(abgr)</b></p>
  52 </td>
  53 <td width="25%"></td>
  54 <td width="6%"></td>
  55 <td width="61%">
  56
  57 <p><b>((abgr) &amp; 0xff)</b></p>
  58 </td>
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  60 <td width="8%"></td>
  61 <td width="-2%">
  62
  63 <p><b>#define TIFFGetG(abgr)</b></p>
  64 </td>
  65 <td width="25%"></td>
  66 <td width="6%"></td>
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  68
  69 <p><b>(((abgr) &gt;&gt; 8) &amp; 0xff)</b></p>
  70 </td>
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  72 <td width="8%"></td>
  73 <td width="-2%">
  74
  75 <p><b>#define TIFFGetB(abgr)</b></p>
  76 </td>
  77 <td width="25%"></td>
  78 <td width="6%"></td>
  79 <td width="61%">
  80
  81 <p><b>(((abgr) &gt;&gt; 16) &amp; 0xff)</b></p>
  82 </td>
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  84 <td width="8%"></td>
  85 <td width="-2%">
  86
  87 <p><b>#define TIFFGetA(abgr)</b></p>
  88 </td>
  89 <td width="25%"></td>
  90 <td width="6%"></td>
  91 <td width="61%">
  92
  93 <p><b>(((abgr) &gt;&gt; 24) &amp; 0xff)</b></p>
  94 </td>
  95 </table>
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 102 <p><b>int TIFFReadRGBATile(TIFF *</b><i>tif</i><b>,
 103 uint32</b> <i>x</i><b>, uint32</b> <i>y</i><b>, uint32
 104 *</b><i>raster</i><b>)</b></p>
 105 </td>
 106 </table>
 107 <a name="DESCRIPTION"></a>
 108 <h2>DESCRIPTION</h2>
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 115 <p><i>TIFFReadRGBATile</i> reads a single tile of a
 116 tile-based image into memory, storing the result in the user
 117 supplied RGBA <i>raster</i>. The raster is assumed to be an
 118 array of width times length 32-bit entries, where width is
 119 the width of a tile (TIFFTAG_TILEWIDTH) and length is the
 120 height of a tile (TIFFTAG_TILELENGTH).</p>
 121 <!-- INDENTATION -->
 122 <p>The <i>x</i> and <i>y</i> values are the offsets from the
 123 top left corner to the top left corner of the tile to be
 124 read. They must be an exact multiple of the tile width and
 125 length.</p>
 126 <!-- INDENTATION -->
 127 <p>Note that the raster is assume to be organized such that
 128 the pixel at location (<i>x</i>,<i>y</i>) is
 129 <i>raster</i>[<i>y</i>*<i>width</i>+<i>x</i>]; with the
 130 raster origin in the <i>lower-left hand corner</i> of the
 131 tile. That is bottom to top organization. Edge tiles which
 132 partly fall off the image will be filled out with
 133 appropriate zeroed areas.</p>
 134 <!-- INDENTATION -->
 135 <p>Raster pixels are 8-bit packed red, green, blue, alpha
 136 samples. The macros <i>TIFFGetR</i>, <i>TIFFGetG</i>,
 137 <i>TIFFGetB</i>, and <i>TIFFGetA</i> should be used to
 138 access individual samples. Images without Associated Alpha
 139 matting information have a constant Alpha of 1.0 (255).</p>
 140 <!-- INDENTATION -->
 141 <p>See the <i>TIFFRGBAImage</i>(3TIFF) page for more details
 142 on how various image types are converted to RGBA values.</p>
 143 </td>
 144 </table>
 145 <a name="NOTES"></a>
 146 <h2>NOTES</h2>
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 153 <p>Samples must be either 1, 2, 4, 8, or 16 bits.
 154 Colorimetric samples/pixel must be either 1, 3, or 4 (i.e.
 155 <i>SamplesPerPixel</i> minus <i>ExtraSamples</i>).</p>
 156 <!-- INDENTATION -->
 157 <p>Palette image colormaps that appear to be incorrectly
 158 written as 8-bit values are automatically scaled to
 159 16-bits.</p>
 160 <!-- INDENTATION -->
 161 <p><i>TIFFReadRGBATile</i> is just a wrapper around the more
 162 general <i>TIFFRGBAImage</i>(3TIFF) facilities. It&rsquo;s
 163 main advantage over the similar <i>TIFFReadRGBAImage()</i>
 164 function is that for large images a single buffer capable of
 165 holding the whole image doesn&rsquo;t need to be allocated,
 166 only enough for one tile. The <i>TIFFReadRGBAStrip()</i>
 167 function does a similar operation for stripped images.</p>
 168 </td>
 169 </table>
 170 <a name="RETURN VALUES"></a>
 171 <h2>RETURN VALUES</h2>
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 178 <p>1 is returned if the image was successfully read and
 179 converted. Otherwise, 0 is returned if an error was
 180 encountered.</p>
 181 </td>
 182 </table>
 183 <a name="DIAGNOSTICS"></a>
 184 <h2>DIAGNOSTICS</h2>
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 191 <p>All error messages are directed to the
 192 <i>TIFFError</i>(3TIFF) routine.</p>
 193 <!-- INDENTATION -->
 194 <p><b>Sorry, can not handle %d-bit pictures</b>. The image
 195 had <i>BitsPerSample</i> other than 1, 2, 4, 8, or 16.</p>
 196 <!-- INDENTATION -->
 197 <p><b>Sorry, can not handle %d-channel images</b>. The image
 198 had <i>SamplesPerPixel</i> other than 1, 3, or 4.</p>
 199 <!-- INDENTATION -->
 200 <p><b>Missing needed &quot;PhotometricInterpretation&quot;
 201 tag</b>. The image did not have a tag that describes how to
 202 display the data.</p>
 203 <!-- INDENTATION -->
 204 <p><b>No &quot;PhotometricInterpretation&quot; tag, assuming
 205 RGB</b>. The image was missing a tag that describes how to
 206 display it, but because it has 3 or 4 samples/pixel, it is
 207 assumed to be <small>RGB.</small></p>
 208 <!-- INDENTATION -->
 209 <p><b>No &quot;PhotometricInterpretation&quot; tag, assuming
 210 min-is-black</b>. The image was missing a tag that describes
 211 how to display it, but because it has 1 sample/pixel, it is
 212 assumed to be a grayscale or bilevel image.</p>
 213 <!-- INDENTATION -->
 214 <p><b>No space for photometric conversion table</b>. There
 215 was insufficient memory for a table used to convert image
 216 samples to 8-bit <small>RGB.</small></p>
 217 <!-- INDENTATION -->
 218 <p><b>Missing required &quot;Colormap&quot; tag</b>. A
 219 Palette image did not have a required <i>Colormap</i>
 220 tag.</p>
 221 <!-- INDENTATION -->
 222 <p><b>No space for tile buffer</b>. There was insufficient
 223 memory to allocate an i/o buffer.</p>
 224 <!-- INDENTATION -->
 225 <p><b>No space for strip buffer</b>. There was insufficient
 226 memory to allocate an i/o buffer.</p>
 227 <!-- INDENTATION -->
 228 <p><b>Can not handle format</b>. The image has a format
 229 (combination of <i>BitsPerSample</i>,
 230 <i>SamplesPerPixel</i>, and
 231 <i>PhotometricInterpretation</i>) that
 232 <i>TIFFReadRGBAImage</i> can not handle.</p>
 233 <!-- INDENTATION -->
 234 <p><b>No space for B&amp;W mapping table</b>. There was
 235 insufficient memory to allocate a table used to map
 236 grayscale data to <small>RGB.</small></p>
 237 <!-- INDENTATION -->
 238 <p><b>No space for Palette mapping table</b>. There was
 239 insufficient memory to allocate a table used to map data to
 240 8-bit <small>RGB.</small></p>
 241 </td>
 242 </table>
 243 <a name="SEE ALSO"></a>
 244 <h2>SEE ALSO</h2>
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 251 <p><b>TIFFOpen</b>(3TIFF), <b>TIFFRGBAImage</b>(3TIFF),
 252 <b>TIFFReadRGBAImage</b>(3TIFF),
 253 <b>TIFFReadRGBAStrip</b>(3TIFF), <b>libtiff</b>(3TIFF)</p>
 254 <!-- INDENTATION -->
 255 <p>Libtiff library home page:
 256 <b>http://www.remotesensing.org/libtiff/</b></p>
 257 </td>
 258 </table>
 259 <hr>
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