TIFFReadScanline(3T)                 Image Format Library C++ Reference Manual



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

SYNOPSIS
     #include <tiffio.h>
     int TIFFReadScanline(TIFF* tif, tdatat buf, uint32 row, tsamplet
     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(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 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.





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TIFFReadScanline(3T)                 Image Format Library C++ Reference Manual



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





















































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