Re-set bitmap mask after applying the duotone filter.

svtools/source/graphic/transformer.cxx

@@ -147,10 +147,11 @@ uno::Reference< graphic::XGraphic > SAL_CALL GraphicTransformer::applyDuotone(
     ::Graphic aGraphic( *::unographic::Graphic::getImplementation( xIFace ) );
 
     BitmapEx    aBitmapEx( aGraphic.GetBitmapEx() );
+    Bitmap      aMask( aBitmapEx.GetMask() );
     Bitmap      aBitmap( aBitmapEx.GetBitmap() );
     BmpFilterParam aFilter( (sal_uLong) nColorOne, (sal_uLong) nColorTwo );
     aBitmap.Filter( BMP_FILTER_DUOTONE, &aFilter );
-    aGraphic = ::Graphic( BitmapEx( aBitmap ) );
+    aGraphic = ::Graphic( BitmapEx( aBitmap, aMask ) );
 
     ::unographic::Graphic* pUnoGraphic = new ::unographic::Graphic();
     pUnoGraphic->init( aGraphic );