[nevcairiel]

Originally Posted by Dogway

Don't raise any eyebrows, every conversion behaves like a lowpass filter when done successively, even with full chroma. This is original chroma plane, this is chroma plane after YUV,RGB,YUV444,RGB,YUV. And yes, it even has a lowpass filter feel to it when I use YUV444 for the last conversion. Test script.

Thats absolute nonsense. Maybe if you store the intermediates in 8-bit all the time (like your test script appears to do), but if you store them with enough precision, it does not result in any image degredation.
I don't know what kind of Matrix madshi uses for this intermediate steps, but for example YCgCo is proven to be mathematically perfectly lossless given enough intermediate precision.