boost::gil::memunit_step

template<typename NonAlignedPixelReference>
std::ptrdiff_t
memunit_step(bit_aligned_pixel_iterator<NonAlignedPixelReference> const&);

template<typename Iterator>
std::ptrdiff_t
memunit_step(memory_based_step_iterator<Iterator> const& p);

template<typename P>
std::ptrdiff_t
memunit_step(P const*);

template<
    typename Iterator,
    typename DFn>
std::iterator_traits<Iterator>::difference_type
memunit_step(dereference_iterator_adaptor<Iterator, DFn> const& p);

template<
    typename IC,
    typename C>
std::ptrdiff_t
memunit_step(planar_pixel_iterator<IC, C> const&);