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- <!-- Creator : groff version 1.18.1 -->
- <!-- CreationDate: Sat Feb 24 18:37:17 2007 -->
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- <meta name="generator" content="groff -Thtml, see www.gnu.org">
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- <title>TIFFReadRGBATile</title>
- </head>
- <body>
- <h1 align=center>TIFFReadRGBATile</h1>
- <a href="#NAME">NAME</a><br>
- <a href="#SYNOPSIS">SYNOPSIS</a><br>
- <a href="#DESCRIPTION">DESCRIPTION</a><br>
- <a href="#NOTES">NOTES</a><br>
- <a href="#RETURN VALUES">RETURN VALUES</a><br>
- <a href="#DIAGNOSTICS">DIAGNOSTICS</a><br>
- <a href="#SEE ALSO">SEE ALSO</a><br>
- <hr>
- <a name="NAME"></a>
- <h2>NAME</h2>
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- <td width="91%">
- <p>TIFFReadRGBATile − read and decode an image tile
- into a fixed-format raster</p>
- </td>
- </table>
- <a name="SYNOPSIS"></a>
- <h2>SYNOPSIS</h2>
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- <p><b>#include <tiffio.h></b></p>
- </td>
- </table>
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- <td width="8%"></td>
- <td width="-2%">
- <p><b>#define TIFFGetR(abgr)</b></p>
- </td>
- <td width="25%"></td>
- <td width="6%"></td>
- <td width="61%">
- <p><b>((abgr) & 0xff)</b></p>
- </td>
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- <td width="8%"></td>
- <td width="-2%">
- <p><b>#define TIFFGetG(abgr)</b></p>
- </td>
- <td width="25%"></td>
- <td width="6%"></td>
- <td width="61%">
- <p><b>(((abgr) >> 8) & 0xff)</b></p>
- </td>
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- <td width="8%"></td>
- <td width="-2%">
- <p><b>#define TIFFGetB(abgr)</b></p>
- </td>
- <td width="25%"></td>
- <td width="6%"></td>
- <td width="61%">
- <p><b>(((abgr) >> 16) & 0xff)</b></p>
- </td>
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- <td width="8%"></td>
- <td width="-2%">
- <p><b>#define TIFFGetA(abgr)</b></p>
- </td>
- <td width="25%"></td>
- <td width="6%"></td>
- <td width="61%">
- <p><b>(((abgr) >> 24) & 0xff)</b></p>
- </td>
- </table>
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- <td width="8%"></td>
- <td width="91%">
- <p><b>int TIFFReadRGBATile(TIFF *</b><i>tif</i><b>,
- uint32_t</b> <i>x</i><b>, uint32_t</b> <i>y</i><b>, uint32_t
- *</b><i>raster</i><b>)</b></p>
- </td>
- </table>
- <a name="DESCRIPTION"></a>
- <h2>DESCRIPTION</h2>
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- <p><i>TIFFReadRGBATile</i> reads a single tile of a
- tile-based image into memory, storing the result in the user
- supplied RGBA <i>raster</i>. The raster is assumed to be an
- array of width times length 32-bit entries, where width is
- the width of a tile (TIFFTAG_TILEWIDTH) and length is the
- height of a tile (TIFFTAG_TILELENGTH).</p>
- <!-- INDENTATION -->
- <p>The <i>x</i> and <i>y</i> values are the offsets from the
- top left corner to the top left corner of the tile to be
- read. They must be an exact multiple of the tile width and
- length.</p>
- <!-- INDENTATION -->
- <p>Note that the raster is assume to be organized such that
- the pixel at location (<i>x</i>,<i>y</i>) is
- <i>raster</i>[<i>y</i>*<i>width</i>+<i>x</i>]; with the
- raster origin in the <i>lower-left hand corner</i> of the
- tile. That is bottom to top organization. Edge tiles which
- partly fall off the image will be filled out with
- appropriate zeroed areas.</p>
- <!-- INDENTATION -->
- <p>Raster pixels are 8-bit packed red, green, blue, alpha
- samples. The macros <i>TIFFGetR</i>, <i>TIFFGetG</i>,
- <i>TIFFGetB</i>, and <i>TIFFGetA</i> should be used to
- access individual samples. Images without Associated Alpha
- matting information have a constant Alpha of 1.0 (255).</p>
- <!-- INDENTATION -->
- <p>See the <i>TIFFRGBAImage</i>(3TIFF) page for more details
- on how various image types are converted to RGBA values.</p>
- </td>
- </table>
- <a name="NOTES"></a>
- <h2>NOTES</h2>
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- <p>Samples must be either 1, 2, 4, 8, or 16 bits.
- Colorimetric samples/pixel must be either 1, 3, or 4 (i.e.
- <i>SamplesPerPixel</i> minus <i>ExtraSamples</i>).</p>
- <!-- INDENTATION -->
- <p>Palette image colormaps that appear to be incorrectly
- written as 8-bit values are automatically scaled to
- 16-bits.</p>
- <!-- INDENTATION -->
- <p><i>TIFFReadRGBATile</i> is just a wrapper around the more
- general <i>TIFFRGBAImage</i>(3TIFF) facilities. It’s
- main advantage over the similar <i>TIFFReadRGBAImage()</i>
- function is that for large images a single buffer capable of
- holding the whole image doesn’t need to be allocated,
- only enough for one tile. The <i>TIFFReadRGBAStrip()</i>
- function does a similar operation for stripped images.</p>
- </td>
- </table>
- <a name="RETURN VALUES"></a>
- <h2>RETURN VALUES</h2>
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- <p>1 is returned if the image was successfully read and
- converted. Otherwise, 0 is returned if an error was
- encountered.</p>
- </td>
- </table>
- <a name="DIAGNOSTICS"></a>
- <h2>DIAGNOSTICS</h2>
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- <p>All error messages are directed to the
- <i>TIFFError</i>(3TIFF) routine.</p>
- <!-- INDENTATION -->
- <p><b>Sorry, can not handle %d-bit pictures</b>. The image
- had <i>BitsPerSample</i> other than 1, 2, 4, 8, or 16.</p>
- <!-- INDENTATION -->
- <p><b>Sorry, can not handle %d-channel images</b>. The image
- had <i>SamplesPerPixel</i> other than 1, 3, or 4.</p>
- <!-- INDENTATION -->
- <p><b>Missing needed "PhotometricInterpretation"
- tag</b>. The image did not have a tag that describes how to
- display the data.</p>
- <!-- INDENTATION -->
- <p><b>No "PhotometricInterpretation" tag, assuming
- RGB</b>. The image was missing a tag that describes how to
- display it, but because it has 3 or 4 samples/pixel, it is
- assumed to be <small>RGB.</small></p>
- <!-- INDENTATION -->
- <p><b>No "PhotometricInterpretation" tag, assuming
- min-is-black</b>. The image was missing a tag that describes
- how to display it, but because it has 1 sample/pixel, it is
- assumed to be a grayscale or bilevel image.</p>
- <!-- INDENTATION -->
- <p><b>No space for photometric conversion table</b>. There
- was insufficient memory for a table used to convert image
- samples to 8-bit <small>RGB.</small></p>
- <!-- INDENTATION -->
- <p><b>Missing required "Colormap" tag</b>. A
- Palette image did not have a required <i>Colormap</i>
- tag.</p>
- <!-- INDENTATION -->
- <p><b>No space for tile buffer</b>. There was insufficient
- memory to allocate an i/o buffer.</p>
- <!-- INDENTATION -->
- <p><b>No space for strip buffer</b>. There was insufficient
- memory to allocate an i/o buffer.</p>
- <!-- INDENTATION -->
- <p><b>Can not handle format</b>. The image has a format
- (combination of <i>BitsPerSample</i>,
- <i>SamplesPerPixel</i>, and
- <i>PhotometricInterpretation</i>) that
- <i>TIFFReadRGBAImage</i> can not handle.</p>
- <!-- INDENTATION -->
- <p><b>No space for B&W mapping table</b>. There was
- insufficient memory to allocate a table used to map
- grayscale data to <small>RGB.</small></p>
- <!-- INDENTATION -->
- <p><b>No space for Palette mapping table</b>. There was
- insufficient memory to allocate a table used to map data to
- 8-bit <small>RGB.</small></p>
- </td>
- </table>
- <a name="SEE ALSO"></a>
- <h2>SEE ALSO</h2>
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- <p><b>TIFFOpen</b>(3TIFF), <b>TIFFRGBAImage</b>(3TIFF),
- <b>TIFFReadRGBAImage</b>(3TIFF),
- <b>TIFFReadRGBAStrip</b>(3TIFF), <b>libtiff</b>(3TIFF)</p>
- <!-- INDENTATION -->
- <p>Libtiff library home page:
- <b>http://www.simplesystems.org/libtiff/</b></p>
- </td>
- </table>
- <hr>
- </body>
- </html>
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