Differences to DirectXTex #3
Description
For some reason, texconv (DirectXTex) converts 16-bit UNORMs and 5/6-bit UNORMs to 8 bit differently than this library.
For 5/6-bit UNORMs, it just repeats the top bits. So e.g. 5->8 is u5 << 3 | u5 >> 2. I have not been able to find the relevant section in texconv's source, but I know that this is what it does by simply looking at its output.
I have not looked into what it does for 16->8.