src/tiff/html/man/TIFFReadScanline.3tiff.html

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<title>TIFFReadScanline</title>
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<h1 align=center>TIFFReadScanline</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>
<a name="NAME"></a>
<h2>NAME</h2>
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<p>TIFFReadScanline &minus; read and decode a scanline of
data from an open <small>TIFF</small> file</p>
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<a name="SYNOPSIS"></a>
<h2>SYNOPSIS</h2>
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<p><b>#include &lt;tiffio.h&gt;</b></p>
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<p><b>int TIFFReadScanline(TIFF *</b><i>tif</i><b>,
tdata_t</b> <i>buf</i><b>, uint32</b> <i>row</i><b>,
tsample_t</b> <i>sample</i><b>)</b></p>
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<a name="DESCRIPTION"></a>
<h2>DESCRIPTION</h2>
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<p>Read the data for the specified row into the (user
supplied) data buffer <i>buf</i>. The data are returned
decompressed and, in the native byte- and bit-ordering, but
are otherwise packed (see further below). The buffer must be
large enough to hold an entire scanline of data.
Applications should call the routine <i>TIFFScanlineSize</i>
to find out the size (in bytes) of a scanline buffer. The
<i>row</i> parameter is always used by
<i>TIFFReadScanline</i>; the <i>sample</i> parameter is used
only if data are organized in separate planes
(<i>PlanarConfiguration</i>=2).</p>
</td>
</table>
<a name="NOTES"></a>
<h2>NOTES</h2>
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<p>The library attempts to hide bit- and byte-ordering
differences between the image and the native machine by
converting data to the native machine order. Bit reversal is
done if the <i>FillOrder</i> tag is opposite to the native
machine bit order. 16- and 32-bit samples are automatically
byte-swapped if the file was written with a byte order
opposite to the native machine byte order,</p>
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<p>In C++ the <i>sample</i> parameter defaults to 0.</p>
</td>
</table>
<a name="RETURN VALUES"></a>
<h2>RETURN VALUES</h2>
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<p><i>TIFFReadScanline</i> returns &minus;1 if it detects an
error; otherwise 1 is returned.</p>
</td>
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<a name="DIAGNOSTICS"></a>
<h2>DIAGNOSTICS</h2>
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<td width="8%"></td>
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<p>All error messages are directed to the
<i>TIFFError</i>(3TIFF) routine.</p>
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<p><b>Compression algorithm does not support random
access</b>. Data was requested in a non-sequential order
from a file that uses a compression algorithm and that has
<i>RowsPerStrip</i> greater than one. That is, data in the
image is stored in a compressed form, and with multiple rows
packed into a strip. In this case, the library does not
support random access to the data. The data should either be
accessed sequentially, or the file should be converted so
that each strip is made up of one row of data.</p>
</td>
</table>
<a name="BUGS"></a>
<h2>BUGS</h2>
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<p>Reading subsampled YCbCR data does not work correctly
because, for <i>PlanarConfiguration</i>=2 the size of a
scanline is not calculated on a per-sample basis, and for
<i>PlanarConfiguration</i>=1 the library does not unpack the
block-interleaved samples; use the strip- and tile-based
interfaces to read these formats.</p>
</td>
</table>
<a name="SEE ALSO"></a>
<h2>SEE ALSO</h2>
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<p><b>TIFFOpen</b>(3TIFF),
<b>TIFFReadEncodedStrip</b>(3TIFF),
<b>TIFFReadRawStrip</b>(3TIFF), <b>libtiff</b>(3TIFF)</p>
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<p>Libtiff library home page:
<b>http://www.remotesensing.org/libtiff/</b></p>
</td>
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Commit	Line	Data
	1	<!-- Creator : groff version 1.18.1 -->
	2	<!-- CreationDate: Sat Feb 24 18:37:17 2007 -->
	3	<html>
	4	<head>
	5	<meta name="generator" content="groff -Thtml, see www.gnu.org">
	6	<meta name="Content-Style" content="text/css">
	7	<title>TIFFReadScanline</title>
	8	</head>
	9	<body>
	10
	11	<h1 align=center>TIFFReadScanline</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="#BUGS">BUGS</a><br>
	19	<a href="#SEE ALSO">SEE ALSO</a><br>
	20
	21	<hr>
	22	<a name="NAME"></a>
	23	<h2>NAME</h2>
	24	<!-- INDENTATION -->
	25	<table width="100%" border=0 rules="none" frame="void"
	26	cols="2" cellspacing="0" cellpadding="0">
	27	<tr valign="top" align="left">
	28	<td width="8%"></td>
	29	<td width="91%">
	30	<p>TIFFReadScanline − read and decode a scanline of
	31	data from an open <small>TIFF</small> file</p>
	32	</td>
	33	</table>
	34	<a name="SYNOPSIS"></a>
	35	<h2>SYNOPSIS</h2>
	36	<!-- INDENTATION -->
	37	<table width="100%" border=0 rules="none" frame="void"
	38	cols="2" cellspacing="0" cellpadding="0">
	39	<tr valign="top" align="left">
	40	<td width="8%"></td>
	41	<td width="91%">
	42	<p><b>#include <tiffio.h></b></p>
	43	<!-- INDENTATION -->
	44	<p><b>int TIFFReadScanline(TIFF *</b><i>tif</i><b>,
	45	tdata_t</b> <i>buf</i><b>, uint32</b> <i>row</i><b>,
	46	tsample_t</b> <i>sample</i><b>)</b></p>
	47	</td>
	48	</table>
	49	<a name="DESCRIPTION"></a>
	50	<h2>DESCRIPTION</h2>
	51	<!-- INDENTATION -->
	52	<table width="100%" border=0 rules="none" frame="void"
	53	cols="2" cellspacing="0" cellpadding="0">
	54	<tr valign="top" align="left">
	55	<td width="8%"></td>
	56	<td width="91%">
	57	<p>Read the data for the specified row into the (user
	58	supplied) data buffer <i>buf</i>. The data are returned
	59	decompressed and, in the native byte- and bit-ordering, but
	60	are otherwise packed (see further below). The buffer must be
	61	large enough to hold an entire scanline of data.
	62	Applications should call the routine <i>TIFFScanlineSize</i>
	63	to find out the size (in bytes) of a scanline buffer. The
	64	<i>row</i> parameter is always used by
	65	<i>TIFFReadScanline</i>; the <i>sample</i> parameter is used
	66	only if data are organized in separate planes
	67	(<i>PlanarConfiguration</i>=2).</p>
	68	</td>
	69	</table>
	70	<a name="NOTES"></a>
	71	<h2>NOTES</h2>
	72	<!-- INDENTATION -->
	73	<table width="100%" border=0 rules="none" frame="void"
	74	cols="2" cellspacing="0" cellpadding="0">
	75	<tr valign="top" align="left">
	76	<td width="8%"></td>
	77	<td width="91%">
	78	<p>The library attempts to hide bit- and byte-ordering
	79	differences between the image and the native machine by
	80	converting data to the native machine order. Bit reversal is
	81	done if the <i>FillOrder</i> tag is opposite to the native
	82	machine bit order. 16- and 32-bit samples are automatically
	83	byte-swapped if the file was written with a byte order
	84	opposite to the native machine byte order,</p>
	85	<!-- INDENTATION -->
	86	<p>In C++ the <i>sample</i> parameter defaults to 0.</p>
	87	</td>
	88	</table>
	89	<a name="RETURN VALUES"></a>
	90	<h2>RETURN VALUES</h2>
	91	<!-- INDENTATION -->
	92	<table width="100%" border=0 rules="none" frame="void"
	93	cols="2" cellspacing="0" cellpadding="0">
	94	<tr valign="top" align="left">
	95	<td width="8%"></td>
	96	<td width="91%">
	97	<p><i>TIFFReadScanline</i> returns −1 if it detects an
	98	error; otherwise 1 is returned.</p>
	99	</td>
	100	</table>
	101	<a name="DIAGNOSTICS"></a>
	102	<h2>DIAGNOSTICS</h2>
	103	<!-- INDENTATION -->
	104	<table width="100%" border=0 rules="none" frame="void"
	105	cols="2" cellspacing="0" cellpadding="0">
	106	<tr valign="top" align="left">
	107	<td width="8%"></td>
	108	<td width="91%">
	109	<p>All error messages are directed to the
	110	<i>TIFFError</i>(3TIFF) routine.</p>
	111	<!-- INDENTATION -->
	112	<p><b>Compression algorithm does not support random
	113	access</b>. Data was requested in a non-sequential order
	114	from a file that uses a compression algorithm and that has
	115	<i>RowsPerStrip</i> greater than one. That is, data in the
	116	image is stored in a compressed form, and with multiple rows
	117	packed into a strip. In this case, the library does not
	118	support random access to the data. The data should either be
	119	accessed sequentially, or the file should be converted so
	120	that each strip is made up of one row of data.</p>
	121	</td>
	122	</table>
	123	<a name="BUGS"></a>
	124	<h2>BUGS</h2>
	125	<!-- INDENTATION -->
	126	<table width="100%" border=0 rules="none" frame="void"
	127	cols="2" cellspacing="0" cellpadding="0">
	128	<tr valign="top" align="left">
	129	<td width="8%"></td>
	130	<td width="91%">
	131	<p>Reading subsampled YCbCR data does not work correctly
	132	because, for <i>PlanarConfiguration</i>=2 the size of a
	133	scanline is not calculated on a per-sample basis, and for
	134	<i>PlanarConfiguration</i>=1 the library does not unpack the
	135	block-interleaved samples; use the strip- and tile-based
	136	interfaces to read these formats.</p>
	137	</td>
	138	</table>
	139	<a name="SEE ALSO"></a>
	140	<h2>SEE ALSO</h2>
	141	<!-- INDENTATION -->
	142	<table width="100%" border=0 rules="none" frame="void"
	143	cols="2" cellspacing="0" cellpadding="0">
	144	<tr valign="top" align="left">
	145	<td width="8%"></td>
	146	<td width="91%">
	147	<p><b>TIFFOpen</b>(3TIFF),
	148	<b>TIFFReadEncodedStrip</b>(3TIFF),
	149	<b>TIFFReadRawStrip</b>(3TIFF), <b>libtiff</b>(3TIFF)</p>
	150	<!-- INDENTATION -->
	151	<p>Libtiff library home page:
	152	<b>http://www.remotesensing.org/libtiff/</b></p>
	153	</td>
	154	</table>
	155	<hr>
	156	</body>
	157	</html>