libtiff/html/man/TIFFReadRGBAImage.3t.html
2003-10-03 11:18:17 +00:00

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<title>TIFFReadRGBAImage</title>
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<h1 align=center>TIFFReadRGBAImage</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="#BUGS">BUGS</a><br>
<a href="#SEE ALSO">SEE ALSO</a><br>
<hr>
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<a name="NAME"></a>
<h2>NAME</h2>
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TIFFReadRGBAImage - read and decode an image into a fixed-format raster</td></table>
<a name="SYNOPSIS"></a>
<h2>SYNOPSIS</h2>
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<b>#include &lt;tiffio.h&gt;</b></td></table>
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<b>#define TIFFGetR(abgr) ((abgr) &amp; 0xff)<br>
#define TIFFGetG(abgr) (((abgr) &gt;&gt; 8) &amp; 0xff)<br>
#define TIFFGetB(abgr) (((abgr) &gt;&gt; 16) &amp; 0xff)<br>
#define TIFFGetA(abgr) (((abgr) &gt;&gt; 24) &amp;
0xff)</b></td></table>
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<b>int TIFFReadRGBAImage(TIFF *</b><i>tif</i><b>, u_long</b>
<i>width</i><b>, u_long</b> <i>height</i><b>, u_long
*</b><i>raster</i><b>, int</b> <i>stopOnError</i><b>)<br>
int TIFFReadRGBAImageOriented(TIFF *</b><i>tif</i><b>,
u_long</b> <i>width</i><b>, u_long</b> <i>height</i><b>,
u_long *</b><i>raster</i><b>, int</b> <i>orientation</i><b>,
int</b> <i>stopOnError</i><b>)</b></td></table>
<a name="DESCRIPTION"></a>
<h2>DESCRIPTION</h2>
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<i>TIFFReadRGBAImage</i> reads a strip- or tile-based image
into memory, storing the result in the user supplied
<i>raster</i>. The raster is assumed to be an array of
<i>width</i> times <i>height</i> 32-bit entries, where
<i>width</i> must be less than or equal to the width of the
image (<i>height</i> may be any non-zero size). If the
raster dimensions are smaller than the image, the image data
is cropped to the raster bounds. If the raster height is
greater than that of the image, then the image data are
placed in the lower part of the raster. (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 lower-left hand corner.)</td></table>
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<i>TIFFReadRGBAImageOriented</i> works like
<i>TIFFReadRGBAImage</i> with except of that user can
specify the raster origin position with the
<i>orientation</i> parameter. Four orientations
supported:</td></table>
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<b>ORIENTATION_TOPLEFT</b></td></table>
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origin in top-left corner,</td></table>
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<b>ORIENTATION_TOPRIGHT</b></td></table>
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origin in top-right corner,</td></table>
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<b>ORIENTATION_BOTLEFT</b></td></table>
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origin in bottom-left corner and</td></table>
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<b>ORIENTATION_BOTRIGHT</b></td></table>
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origin in bottom-right corner.</td></table>
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If you choose <b>ORIENTATION_BOTLEFT</b> result will be the
same as returned by the
<i>TIFFReadRGBAImage.</i></td></table>
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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).</td></table>
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<i>TIFFReadRGBAImage</i> converts non-8-bit images by
scaling sample values. Palette, grayscale, bilevel,
<small>CMYK</small> , and YCbCr images are converted to
<small>RGB</small> transparently. Raster pixels are returned
uncorrected by any colorimetry information present in the
directory.</td></table>
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The paramater <i>stopOnError</i> specifies how to act if an
error is encountered while reading the image. If
<i>stopOnError</i> is non-zero, then an error will terminate
the operation; otherwise <i>TIFFReadRGBAImage</i> will
continue processing data until all the possible data in the
image have been requested.</td></table>
<a name="NOTES"></a>
<h2>NOTES</h2>
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In C++ the <i>stopOnError</i> parameter defaults to
0.</td></table>
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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>).</td></table>
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Palettte image colormaps that appear to be incorrectly
written as 8-bit values are automatically scaled to
16-bits.</td></table>
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<i>TIFFReadRGBAImage</i> is just a wrapper around the more
general <i>TIFFRGBAImage</i>(3T) facilities.</td></table>
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<h2>RETURN VALUES</h2>
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1 is returned if the image was successfully read and
converted. Otherwise, 0 is returned if an error was
encountered and <i>stopOnError</i> is zero.</td></table>
<a name="DIAGNOSTICS"></a>
<h2>DIAGNOSTICS</h2>
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All error messages are directed to the <i>TIFFError</i>(3T)
routine.</td></table>
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<b>Sorry, can not handle %d-bit pictures</b>. The image had
<i>BitsPerSample</i> other than 1, 2, 4, 8, or
16.</td></table>
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<b>Sorry, can not handle %d-channel images</b>. The image
had <i>SamplesPerPixel</i> other than 1, 3, or
4.</td></table>
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<b>Missing needed &quot;PhotometricInterpretation&quot;
tag</b>. The image did not have a tag that describes how to
display the data.</td></table>
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<b>No &quot;PhotometricInterpretation&quot; 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></td></table>
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<b>No &quot;PhotometricInterpretation&quot; 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.</td></table>
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<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></td></table>
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<b>Missing required &quot;Colormap&quot; tag</b>. A Palette
image did not have a required <i>Colormap</i>
tag.</td></table>
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<b>No space for tile buffer</b>. There was insufficient
memory to allocate an i/o buffer.</td></table>
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<b>No space for strip buffer</b>. There was insufficient
memory to allocate an i/o buffer.</td></table>
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<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.</td></table>
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<b>No space for B&amp;W mapping table</b>. There was
insufficient memory to allocate a table used to map
grayscale data to <small>RGB.</small></td></table>
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<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></td></table>
<a name="BUGS"></a>
<h2>BUGS</h2>
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Orientations other than bottom-left, or top-left are not
handled correctly.</td></table>
<a name="SEE ALSO"></a>
<h2>SEE ALSO</h2>
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<i>libtiff</i>(3T), <i>TIFFOpen</i>(3T),
<i>TIFFRGBAImage</i>(3T), <i>TIFFReadRGBAStrip</i>(3T),
<i>TIFFReadRGBATile</i>(3T)</td></table>
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