TIFFReadScanline(3T)													      TIFFReadScanline(3T)

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 sample)

DESCRIPTION

       Read  the data for the specified row into the (user supplied) data buffer 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.
       Applications  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 organized 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
       machine order.  Bit reversal is done if the FillOrder tag is opposite to the native machine bit order.  16- and 32-bit samples are automat-
       ically 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 returned.

DIAGNOSTICS

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

       Compression algorithm does not support random access.  Data was requested 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  sequen-
       tially, 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 PlanarConfiguration=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 inter-
       faces to read these formats.

SEE ALSO

       libtiff(3T), TIFFOpen(3T), TIFFReadEncodedStrip(3T), TIFFReadRawStrip(3T)

								 October 15, 1995					      TIFFReadScanline(3T)