====== Luma ======

===== BT. 709 =====
Luminance of a pixel (read more on [[https://en.wikipedia.org/wiki/Rec._709|Wikipeia]]) is a measure of perceived brightness and is calculated in SUB2r code using the following formula:

\[
 luma = 0.2126R + 0.7152G + 0.0722B
\]

This is in accordance with the HDTV's BT.709 recommendation (and not the "expected" CCIR 601) and the UVC descriptors for USB video transmission reflect that choice.

===== BT. 601 =====
A.k.a. [[https://en.wikipedia.org/wiki/Rec._601|CCIR 601]]
If we were to chose the CCIR 601, which is used in most digital standard definitions, the coefficients would be:

\[
 luma = 0.299R + 0.587G + 0.114B
\]

===== BT. 2020 =====
According to [[https://en.wikipedia.org/wiki/Rec._2020|Wikipedia]] the new standard's coefficients are yet different still:

\[
 luma = 0.2627R + 0.678G + 0.0593B
\]