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2011.04.15 11:50 "[Tiff] File size too large when using custom tiff tags", by
2011.04.15 13:04 "Re: [Tiff] File size too large when using custom tiff tags", by Frank Warmerdam

2011.04.15 11:50 "[Tiff] File size too large when using custom tiff tags", by

Hey guys,

I'm using Libtiff to store a array of long values (32 bit) in a custom tiff tag. The type of the tag is TIFF_LONG. Everything works pretty well, except that the file size is too large by factor 2.

For example, there is an array of 361000 long values. The file size should be ~ 1.44 MB (size of data ) + 531 KB ( size of the picture) = 1.971 MB.

But the size is 3.4 MB. How could that be? Any Ideas?

That's my cutom tag:

void TagExtender( TIFF *tiff )

{

      assert( tiff );

      static const TIFFFieldInfo xtiffFieldInfo[] = {

            { TIFFTAG_LAYER0, -3, -3, TIFF_LONG, FIELD_CUSTOM, 1, 1,
"Data" },

      };

      TIFFMergeFieldInfo( tiff, xtiffFieldInfo,

            sizeof(xtiffFieldInfo) / sizeof(xtiffFieldInfo[0]) );

}

This is how the array is stored:

class TiffHandler{

private:

      TIFF              * m_tiff;

...

void TiffHandler::AddData( int directory, const std::vector<long>& data
)

{

      assert( m_tiff );

      assert( data.size() );

      TIFFSetTagExtender( TagExtender );

      TIFFSetErrorHandler( TIFFError );

      TIFFSetDirectory( m_tiff, directory );

      TIFFSetField( m_tiff, TIFFTAG_LAYER0, data.size(), &data[0] );

      TIFFRewriteDirectory( m_tiff );

}