Extracting A Yellow Matte Using Either Colorx Or Reorder Node

[user_deleted]

Is it possible to extracting a Yellow matte using either colorx or reorder node? I can't figure it out I put a+b in each channel but it doesn't seem to work. Help anyone?

[user_deleted]

there is an excellent macro by Howard Jones called secondary color pack which probably would do what you want:
http://www.highend3d.com/shake/downloads/m...-Pack-4376.html

an other idea worth a try could be to use a color keyer, like primatte.
++ chris

[user_deleted]

Hi,

ColorX1 = ColorX(0, r, g, b, 1-(2-(g+r)), z);

Try That. Just view the alpha. Should do the trick.

Tim Walker

[user_deleted]

clever trick, but it doesnt really look like an accurate yellow mask to me..

compare this sample (which is essentially your colorx expression):

CODE
Color1 = Color(720, 576, 1, 1, 1, 1, 1, 0);
Grad1 = Grad(720, 576, 1, 0.5, 0.5, 1, 0, 0, 1, 0, 0, 1, 0.5,
    1, 0, 1, 0.5, 0, 1, 0, 0, 0, 0, 1, 0);
Reorder2 = Reorder(Grad1, "gggg");
Reorder3 = Reorder(Grad1, "rrrr");
ISub2 = ISub(Color1, Reorder2, 1, 100);
ISub3 = ISub(Reorder3, ISub2, 1, 100);

to the cmy mask macro:
CODE
Grad2 = Grad(720, 576, 1, 0.5, 0.5, 1, 0, 0, 1, 0, 0, 1, 0.5,
    1, 0, 1, 0.5, 0, 1, 0, 0, 0, 0, 1, 0);
RGB_CMY_Mattes1 = RGB_CMY_Mattes(Grad2, 4, 2, 3, 1, 0.8, 2, 0,
    0, 0.8311953);
Reorder1 = Reorder(RGB_CMY_Mattes1, "bbbb");

[joojaa]

theres a erithmetic mistake in the

ColorX1 = ColorX(0, r, g, b, 1-(2-(g+r)), z);

But more than thet itheres a big thinking error in it too. g+r is way too wide

(r+g)/2-b

yields a much better yellow matte.

Al tough a working in hsv sapace is better and easier to definitively as the above cant account for white yellows