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TIFFReadScanline(3TIFF)				       TIFFReadScanline(3TIFF)

NAME
       TIFFReadScanline	- read and decode a scanline of	data from an open TIFF
       file

SYNOPSIS
       #include	<tiffio.h>

       int TIFFReadScanline(TIFF *tif, tdata_t buf, uint32 row,	tsample_t sam-
       ple)

DESCRIPTION
       Read  the data for the specified	row into the (user supplied) data buf-
       fer buf.	 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.	Appli-
       cations	should	call the routine TIFFScanlineSize to find out the size
       (in bytes) of a scanline	buffer.	 The row parameter is always  used  by
       TIFFReadScanline;  the  sample parameter	is used	only if	data are orga-
       nized in	separate planes	(PlanarConfiguration=2).

NOTES
       The library attempts to hide bit- and byte-ordering differences between
       the  image  and the native machine by converting	data to	the native ma-
       chine order.  Bit reversal is done if the FillOrder 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,

       In C++ the sample parameter defaults to 0.

RETURN VALUES
       TIFFReadScanline	 returns -1 if it detects an error; otherwise 1	is re-
       turned.

DIAGNOSTICS
       All error messages are directed to the TIFFError(3TIFF) routine.

       Compression algorithm does not support random  access.	Data  was  re-
       quested	in  a non-sequential order from	a file that uses a compression
       algorithm and that has RowsPerStrip 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.

BUGS
       Reading subsampled YCbCR	data does not work correctly because, for Pla-
       narConfiguration=2 the size of a	scanline is not	calculated on  a  per-
       sample basis, and for PlanarConfiguration=1 the library does not	unpack
       the block-interleaved samples; use the strip- and tile-based interfaces
       to read these formats.

SEE ALSO
       TIFFOpen(3TIFF),	 TIFFReadEncodedStrip(3TIFF), TIFFReadRawStrip(3TIFF),
       libtiff(3TIFF)

       Libtiff library home page: http://www.simplesystems.org/libtiff/

libtiff			       October 15, 1995	       TIFFReadScanline(3TIFF)

NAME | SYNOPSIS | DESCRIPTION | NOTES | RETURN VALUES | DIAGNOSTICS | BUGS | SEE ALSO

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