[dom0]

> I wonder what's meant here. Is it just a matter of rounding or is there more to it than that?

Many colour spaces are non-overlapping, ie. one colour space has colours a different colour space simply doesn't have, so converting between them is often lossy and thus non-invertible.

[dragonwriter]

> Many colour spaces are non-overlapping, ie. one colour space has colours a different colour space simply doesn't have

Wouldn't that be overlapping but non-coextensive? Non-overlapping would be no colors in common between color spaces, which would be odd.

[dom0]

Yes. I didn't realize that difference between my intermediate language and the output language of these comments :)