Well I did it exactly the same as mentioned here but somehow I end up with exact the same result as the original, what seems like magic to me anyway, you know the magician that makes the most complicated knots and pulls the cord and it's normal again
I also found this on another site.
R = 2R - (G+B)/2
G = 2G - (R+B)/2
B = 2B - (R+G)/2
And apply that with the original.
I will try that tonight when I'm back at my studio.
Greetings,
Frank