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TIFFReadDirectory.3tiff.html
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TIFFReadDirectory.3tiff.html
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<!-- Creator : groff version 1.18.1 -->
<!-- CreationDate: Sat Feb 24 18:37:16 2007 -->
<html>
<head>
<meta name="generator" content="groff -Thtml, see www.gnu.org">
<meta name="Content-Style" content="text/css">
<title>TIFFReadDirectory</title>
</head>
<body>
<h1 align=center>TIFFReadDirectory</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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<p><big>TIFFReadDirectory − get the contents of the
next directory in an open</big> TIFF <big>file</big></p>
</td>
</table>
<a name="SYNOPSIS"></a>
<h2>SYNOPSIS</h2>
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<p><big><b>#include <tiffio.h></b></big></p>
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<p><big><b>int TIFFReadDirectory(TIFF
*</b><i>tif</i><b>)</b></big></p>
</td>
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<a name="DESCRIPTION"></a>
<h2>DESCRIPTION</h2>
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<p><big>Read the next directory in the specified file and
make it the current directory. Applications only need to
call <i>TIFFReadDirectory</i> to read multiple subfiles in a
single</big> TIFF <big>file— the first directory in a
file is automatically read when <i>TIFFOpen</i> is
called.</big></p>
</td>
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<a name="NOTES"></a>
<h2>NOTES</h2>
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<p><big>If the library is compiled with</big>
STRIPCHOP_SUPPORT <big>enabled, then images that have a
single uncompressed strip or tile of data are automatically
treated as if they were made up of multiple strips or tiles
of approximately 8 kilobytes each. This operation is done
only in-memory; it does not alter the contents of the file.
However, the construction of the ‘‘chopped
strips’’ is visible to the application through
the number of strips [tiles] returned by
<i>TIFFNumberOfStrips</i>
[<i>TIFFNumberOfTiles</i>].</big></p>
</td>
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<a name="RETURN VALUES"></a>
<h2>RETURN VALUES</h2>
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<p><big>If the next directory was successfully read, 1 is
returned. Otherwise, 0 is returned if an error was
encountered, or if there are no more directories to be
read.</big></p>
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<a name="DIAGNOSTICS"></a>
<h2>DIAGNOSTICS</h2>
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<p><big>All error messages are directed to the
<i>TIFFError</i>(3TIFF) routine. All warning messages are
directed to the <i>TIFFWarning</i>(3TIFF) routine.</big></p>
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<p><big><b>Seek error accessing TIFF directory</b>. An error
occurred while positioning to the location of the
directory.</big></p>
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<p><big><b>Wrong data type %d for field "%s"</b>.
The tag entry in the directory had an incorrect data type.
For example, an <i>ImageDescription</i> tag with a</big>
SHORT <big>data type.</big></p>
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<p><big><b>TIFF directory is missing required "%s"
field</b>. The specified tag is required to be present by
the</big> TIFF <big>5.0 specification, but is missing. The
directory is (usually) unusable.</big></p>
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<p><big><b>%s: Rational with zero denominator</b>. A
directory tag has a</big> RATIONAL <big>value whose
denominator is zero.</big></p>
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<p><big><b>Incorrect count %d for field "%s" (%lu,
expecting %lu); tag ignored</b>. The specified tag’s
count field is bad. For example, a count other than 1 for a
<i>SubFileType</i> tag.</big></p>
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<p><big><b>Cannot handle different per-sample values for
field "%s"</b>. The tag has <i>SamplesPerPixel</i>
values and they are not all the same; e.g.
<i>BitsPerSample</i>. The library is unable to handle images
of this sort.</big></p>
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<p><big><b>Count mismatch for field "%s";
expecting %d, got %d</b>. The count field in a tag does not
agree with the number expected by the library. This should
never happen, so if it does, the library refuses to read the
directory.</big></p>
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<p><big><b>Invalid TIFF directory; tags are not sorted in
ascending order</b>. The directory tags are not properly
sorted as specified in the</big> TIFF <big>5.0
specification. This error is not fatal.</big></p>
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<p><big><b>Ignoring unknown field with tag %d (0x%x)</b>. An
unknown tag was encountered in the directory; the library
ignores all such tags.</big></p>
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<p><big><b>TIFF directory is missing requred
"ImageLength" field</b>. The image violates the
specification by not having a necessary field. There is no
way for the library to recover from this error.</big></p>
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<p><big><b>TIFF directory is missing requred
"PlanarConfig" field</b>. The image violates the
specification by not having a necessary field. There is no
way for the library to recover from this error.</big></p>
<!-- INDENTATION -->
<p><big><b>TIFF directory is missing requred
"StripOffsets" field</b>. The image has multiple
strips, but is missing the tag that specifies the file
offset to each strip of data. There is no way for the
library to recover from this error.</big></p>
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<p><big><b>TIFF directory is missing requred
"TileOffsets" field</b>. The image has multiple
tiles, but is missing the tag that specifies the file offset
to each tile of data. There is no way for the library to
recover from this error.</big></p>
<!-- INDENTATION -->
<p><big><b>TIFF directory is missing required
"StripByteCounts" field</b>. The image has
multiple strips, but is missing the tag that specifies the
size of each strip of data. There is no way for the library
to recover from this error.</big></p>
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<p><big><b>TIFF directory is missing required
"StripByteCounts" field, calculating from
imagelength</b>. The image violates the specification by not
having a necessary field. However, when the image is
comprised of only one strip or tile, the library will
estimate the missing value based on the file size.</big></p>
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<p><big><b>Bogus "StripByteCounts" field, ignoring
and calculating from imagelength</b>. Certain vendors
violate the specification by writing zero for the
StripByteCounts tag when they want to leave the value
unspecified. If the image has a single strip, the library
will estimate the missing value based on the file
size.</big></p>
</td>
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<a name="SEE ALSO"></a>
<h2>SEE ALSO</h2>
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<p><big><b>TIFFOpen</b>(3TIFF),
<b>TIFFWriteDirectory</b>(3TIFF),
<b>TIFFSetDirectory</b>(3TIFF),
<b>TIFFSetSubDirectory</b>(3TIFF),
<b>libtiff</b>(3TIFF)</big></p>
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<p><big>Libtiff library home page:
<b>http://www.simplesystems.org/libtiff/</b></big></p>
</td>
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