[Boost-users] [GIL] convert image view to const image view

I originally hoped that an actual function argument of type GIL mutable image view (e.g., gray8_view_t) would be automatically promoted to a (immutable or const) view (e.g., gray8c_view_t). But my experience (with version 1.44.0) indicates otherwise. It also seems like the const_view function, which generates a (const) view from an image is not overloaded to do the same using a mutable view. Obviously, I'm just getting starting using GIL, since this sort of conversion would, I presume, be used often. I've been searching the online documentation without success. Can someone point me to the answer for this basic task? In the meantime, I'll be reading the GIL header files. Thanks.