Even though this is still an unofficial feature, could you add "store as jpeg" checkbox, maybe with the usual compression quality slider?
I normally use the VFB history to see how things have changed over time, rather than reverting to another render in all its multi-channel, full float glory (which quickly chews up disk space and takes forever to load them into the VFB when they're big).
I normally use the VFB history to see how things have changed over time, rather than reverting to another render in all its multi-channel, full float glory (which quickly chews up disk space and takes forever to load them into the VFB when they're big).