140 lines
3.7 KiB
HTML
140 lines
3.7 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML><HEAD><TITLE>Manpage of TIFFReadScanline</TITLE>
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</HEAD><BODY BGCOLOR=WHITE><FONT FACE="helvetica, sans, arial">
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<H1>TIFFReadScanline</H1>
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Section: Misc. Reference Manual Pages (3T)<BR>Updated: October 15, 1995<BR><A HREF="#index">Index</A>
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<BR><A HREF="index.html">Return to Main Contents</A>
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<HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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TIFFReadScanline - read and decode a scanline of data from an open
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<FONT SIZE="-1">TIFF</FONT>
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file
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>#include <<A HREF="file:/usr/include/tiffio.h">tiffio.h</A>></B>
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<BR>
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<B>int TIFFReadScanline(TIFF* tif, tdata_t buf, uint32 row, tsample_t sample)</B>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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Read the data for the specified row into the (user supplied)
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data buffer
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<I>buf</I>.
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The data are returned decompressed and, in the native byte-
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and bit-ordering, but are otherwise packed (see further below).
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The buffer must be large enough to hold an entire scanline of data.
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Applications should call the routine
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<I>TIFFScanlineSize</I>
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to find out the size (in bytes) of a scanline buffer.
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The
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<I>row</I>
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parameter is always used by
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<I>TIFFReadScanline</I>;
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the
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<I>sample</I>
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parameter is used only if data are organized in separate planes (<I>PlanarConfiguration</I>=2).
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<A NAME="lbAE"> </A>
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<H2>NOTES</H2>
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The library attempts to hide bit- and byte-ordering differences
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between the image and the native machine by converting data
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to the native machine order.
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Bit reversal is done if the
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<I>FillOrder</I>
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tag is opposite to the native machine bit order.
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16- and 32-bit samples are automatically byte-swapped if the
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file was written with a byte order opposite to the native
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machine byte order,
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<P>
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In C++ the
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<I>sample</I>
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parameter defaults to 0.
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<A NAME="lbAF"> </A>
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<H2>RETURN VALUES</H2>
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<I>TIFFReadScanline</I>
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returns -1 if it detects an error; otherwise 1 is returned.
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<A NAME="lbAG"> </A>
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<H2>DIAGNOSTICS</H2>
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All error messages are directed to the
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<I><A HREF="TIFFError.3t.html">TIFFError</A></I>(3T)
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routine.
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<P>
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<B>Compression algorithm does not support random access</B>.
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Data was requested in a non-sequential order from a file that
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uses a compression algorithm and that has
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<I>RowsPerStrip</I>
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greater than one.
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That is, data in the image is stored in a compressed form,
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and with multiple rows packed into a strip.
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In this case, the library does not support random access to the data.
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The data should either be accessed sequentially, or the file
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should be converted so that each strip is made up of one row
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of data.
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<A NAME="lbAH"> </A>
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<H2>BUGS</H2>
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Reading subsampled YCbCR data does not work correctly
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because, for
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<I>PlanarConfiguration</I>=2
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the size of a scanline is not calculated on a per-sample basis,
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and for
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<I>PlanarConfiguration</I>=1
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the library does not unpack the block-interleaved samples; use
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the strip- and tile-based interfaces to read these formats.
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<A NAME="lbAI"> </A>
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<H2>SEE ALSO</H2>
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<I><A HREF="libtiff.3t.html">libtiff</A></I>(3T),
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<I><A HREF="TIFFOpen.3t.html">TIFFOpen</A></I>(3T),
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<I><A HREF="TIFFReadEncodedStrip.3t.html">TIFFReadEncodedStrip</A></I>(3T),
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<I><A HREF="TIFFReadRawStrip.3t.html">TIFFReadRawStrip</A></I>(3T)
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT><A HREF="#lbAB">NAME</A><DD>
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<DT><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT><A HREF="#lbAE">NOTES</A><DD>
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<DT><A HREF="#lbAF">RETURN VALUES</A><DD>
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<DT><A HREF="#lbAG">DIAGNOSTICS</A><DD>
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<DT><A HREF="#lbAH">BUGS</A><DD>
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<DT><A HREF="#lbAI">SEE ALSO</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="index.html">man2html</A>,
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using the manual pages.<BR>
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Time: 01:31:38 GMT, November 23, 1999
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