Luminance level?

[Insolit]

I have just made a few encodings following the CCE guide present here in doom9 site.
All the encodings I made, although the image was great, I got much brighter image than the source.
So I decided to test the setting, 0 to 255 in luminance, and I got a perfect match.
Why is 16 to 235 the default setting? Is there any special reason?

[wmansir]

Read: Q12: How do I set the "Luminance Level" option correctly?

in the FAQ at the top of this forum.