concept ImageViewConcept<RandomAccess2DImageViewConcept View> {
where PixelValueConcept<value_type>;
where PixelIteratorConcept<x_iterator>;
where PixelIteratorConcept<y_iterator>;
where x_coord_t == y_coord_t;
typename coord_t = x_coord_t;
std::size_t View::num_channels() const;
};