There are a few formats that use a curve and less bits. They do become lossy and doing dithering on decompress is useful to avoid banding.
The Nikon one you mention was only used very early and is decoded by decode_8bit_wtable() in that file. It's just looking up the 8 bit value in the table and then adding some randomness to prevent the banding.
https://github.com/pedrocr/rawloader/blob/a59bb78d156277781a...
There are a few formats that use a curve and less bits. They do become lossy and doing dithering on decompress is useful to avoid banding.
The Nikon one you mention was only used very early and is decoded by decode_8bit_wtable() in that file. It's just looking up the 8 bit value in the table and then adding some randomness to prevent the banding.