for( unsigned int d = 0; d < I::ImageDimension; d++ )
dist += std::abs( long( a[ d ] ) - long( b[ d ] ) );
if( this->m_NeighborhoodOrder == 1 )
for( unsigned int d = 0; d < I::ImageDimension; d++ )
dist += std::abs( long( a[ d ] ) - long( b[ d ] ) );
if( this->m_NeighborhoodOrder == 1 )