A1ex, I notice on the site front page that the vectorscope might be coming soon. Have you considered adding a skin tone line to the scope?
The "I" line in a YIQ color space lays along the axis of human skin color (regardless of race/skin type).
Check out http://en.wikipedia.org/wiki/YIQ (http://en.wikipedia.org/wiki/YIQ) I see that there are already color indicators, but all the vectorscopes I have used retain the I axis even if used for PAL YUV space.
The reason http://www.kdenlive.org/users/granjow/vectorscope-what-i-and-q-lines-are-good (http://www.kdenlive.org/users/granjow/vectorscope-what-i-and-q-lines-are-good)
Interesting for me, thanks for the link.
Done, can you check if the slope of I/Q lines is correct?
(http://bitbucket.org/hudson/magic-lantern/raw/c6b3a46fdf90/doc/vectorscope.png)