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
       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
       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
       returned.

DIAGNOSTICS
       All error messages are directed to the TIFFError(3TIFF) 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 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
       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
       interfaces to read these formats.

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

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



libtiff                        October 15, 1995        TIFFReadScanline(3TIFF)
