258 lines
9.7 KiB
HTML
258 lines
9.7 KiB
HTML
<html>
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<meta name="generator" content="groff -Thtml, see www.gnu.org">
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<meta name="Content-Style" content="text/css">
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<title>TIFFReadRGBATile</title>
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</head>
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<body>
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<h1 align=center>TIFFReadRGBATile</h1>
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<a href="#NAME">NAME</a><br>
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<a href="#SYNOPSIS">SYNOPSIS</a><br>
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<a href="#DESCRIPTION">DESCRIPTION</a><br>
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<a href="#NOTES">NOTES</a><br>
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<a href="#RETURN VALUES">RETURN VALUES</a><br>
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<a href="#DIAGNOSTICS">DIAGNOSTICS</a><br>
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<a href="#SEE ALSO">SEE ALSO</a><br>
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<hr>
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<!-- Creator : groff version 1.17.2 -->
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<!-- CreationDate: Mon Dec 22 00:39:25 2003 -->
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<a name="NAME"></a>
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<h2>NAME</h2>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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TIFFReadRGBATile - read and decode an image tile into a fixed-format raster</td></table>
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<a name="SYNOPSIS"></a>
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<h2>SYNOPSIS</h2>
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<pre><b>#include <tiffio.h>
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#define TIFFGetR(abgr) ((abgr) & 0xff)
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#define TIFFGetG(abgr) (((abgr) >> 8) & 0xff)
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#define TIFFGetB(abgr) (((abgr) >> 16) & 0xff)
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#define TIFFGetA(abgr) (((abgr) >> 24) & 0xff)
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int TIFFReadRGBATile(TIFF* tif, uint32 x, uint32 y, uint32 * raster )
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</b></pre></td></table>
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<a name="DESCRIPTION"></a>
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<h2>DESCRIPTION</h2>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<i>TIFFReadRGBATile</i> reads a single tile of a tile-based
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image into memory, storing the result in the user supplied
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RGBA <i>raster</i>. The raster is assumed to be an array of
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width times length 32-bit entries, where width is the width
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of a tile (TIFFTAG_TILEWIDTH) and length is the height of a
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tile (TIFFTAG_TILELENGTH).</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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The <i>x</i> and <i>y</i> values are the offsets from the
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top left corner to the top left corner of the tile to be
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read. They must be an exact multiple of the tile width and
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length.</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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Note that the raster is assume to be organized such that the
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pixel at location (<i>x</i>,<i>y</i>) is
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<i>raster</i>[<i>y</i>*<i>width</i>+<i>x</i>]; with the
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raster origin in the <i>lower-left hand corner</i> of the
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tile. That is bottom to top organization. Edge tiles which
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partly fall off the image will be filled out with
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appropriate zeroed areas.</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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Raster pixels are 8-bit packed red, green, blue, alpha
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samples. The macros <i>TIFFGetR</i>, <i>TIFFGetG</i>,
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<i>TIFFGetB</i>, and <i>TIFFGetA</i> should be used to
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access individual samples. Images without Associated Alpha
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matting information have a constant Alpha of 1.0
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(255).</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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See the <i>TIFFRGBAImage</i>(3T) page for more details on
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how various image types are converted to RGBA
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values.</td></table>
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<a name="NOTES"></a>
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<h2>NOTES</h2>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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Samples must be either 1, 2, 4, 8, or 16 bits. Colorimetric
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samples/pixel must be either 1, 3, or 4 (i.e.
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<i>SamplesPerPixel</i> minus
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<i>ExtraSamples</i>).</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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Palette image colormaps that appear to be incorrectly
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written as 8-bit values are automatically scaled to
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16-bits.</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<i>TIFFReadRGBATile</i> is just a wrapper around the more
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general <i>TIFFRGBAImage</i>(3T) facilities. It's main
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advantage over the similar <i>TIFFReadRGBAImage()</i>
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function is that for large images a single buffer capable of
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holding the whole image doesn't need to be allocated, only
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enough for one tile. The <i>TIFFReadRGBAStrip()</i> function
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does a similar operation for stripped images.</td></table>
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<a name="RETURN VALUES"></a>
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<h2>RETURN VALUES</h2>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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1 is returned if the image was successfully read and
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converted. Otherwise, 0 is returned if an error was
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encountered.</td></table>
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<a name="DIAGNOSTICS"></a>
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<h2>DIAGNOSTICS</h2>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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All error messages are directed to the <i>TIFFError</i>(3T)
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routine.</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<b>Sorry, can not handle %d-bit pictures</b>. The image had
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<i>BitsPerSample</i> other than 1, 2, 4, 8, or
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16.</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<b>Sorry, can not handle %d-channel images</b>. The image
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had <i>SamplesPerPixel</i> other than 1, 3, or
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4.</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<b>Missing needed "PhotometricInterpretation"
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tag</b>. The image did not have a tag that describes how to
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display the data.</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<b>No "PhotometricInterpretation" tag, assuming
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RGB</b>. The image was missing a tag that describes how to
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display it, but because it has 3 or 4 samples/pixel, it is
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assumed to be <small>RGB.</small></td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<b>No "PhotometricInterpretation" tag, assuming
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min-is-black</b>. The image was missing a tag that describes
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how to display it, but because it has 1 sample/pixel, it is
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assumed to be a grayscale or bilevel image.</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<b>No space for photometric conversion table</b>. There was
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insufficient memory for a table used to convert image
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samples to 8-bit <small>RGB.</small></td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<b>Missing required "Colormap" tag</b>. A Palette
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image did not have a required <i>Colormap</i>
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tag.</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<b>No space for tile buffer</b>. There was insufficient
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memory to allocate an i/o buffer.</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<b>No space for strip buffer</b>. There was insufficient
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memory to allocate an i/o buffer.</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<b>Can not handle format</b>. The image has a format
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(combination of <i>BitsPerSample</i>,
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<i>SamplesPerPixel</i>, and
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<i>PhotometricInterpretation</i>) that
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<i>TIFFReadRGBAImage</i> can not handle.</td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<b>No space for B&W mapping table</b>. There was
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insufficient memory to allocate a table used to map
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grayscale data to <small>RGB.</small></td></table>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<b>No space for Palette mapping table</b>. There was
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insufficient memory to allocate a table used to map data to
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8-bit <small>RGB.</small></td></table>
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<a name="SEE ALSO"></a>
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<h2>SEE ALSO</h2>
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<table width="100%" border=0 rules="none" frame="void"
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cols="2" cellspacing="0" cellpadding="0">
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<tr valign="top" align="left">
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<td width="10%"></td><td width="90%">
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<i>libtiff</i>(3T), <i>TIFFOpen</i>(3T),
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<i>TIFFRGBAImage</i>(3T), <i>TIFFReadRGBAImage</i>(3T),
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<i>TIFFReadRGBAStrip</i>(3T)</td></table>
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<hr>
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</body>
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</html>
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