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_t 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.simplesystems.org/libtiff/

libtiff                                         October 15, 1995                         TIFFReadScanline(3TIFF)