Luma

Luminance of a pixel (read more on Wikipeia) is a measure of perceived brightness and is calculated in SUB2r code using the following formula:

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

in accordance with the BT.709 recommendation (and not the “expected” CCIR 601) and the UVC descriptors for USB video transmission reflect that choice.