def gauss_blur( sigma, max_error = 1.0 / 0x100 )
      filter_type = DFLOAT.align typecode
      filter = Sequence[ *Array.gauss_blur_filter( sigma, max_error / dimension ) ].
        to_type filter_type
      ( dimension - 1 ).downto( 0 ).inject self do |retval,i|
        retval.convolve filter
      end
    end
def gauss_blur( sigma, max_error = 1.0 / 0x100 )
      filter_type = DFLOAT.align typecode
      filter = Sequence[ *Array.gauss_blur_filter( sigma, max_error / dimension ) ].
        to_type filter_type
      ( dimension - 1 ).downto( 0 ).inject self do |retval,i|
        retval.convolve filter
      end
    end
Gaussian blur

 @param [Float] sigma Spread of Gauss bell.
 @param [Float] max_error Error of approximated filter.

 @return [Node] Result of filter operation.