Pixel Bender Chroma Keying code for flex3 / as3

Does anybody know where i can find a good chroma keying pixel bender code example. Or does anybody know how to write such a code in pixel bender. Or a create pixel bender tutorial to create开发者_高级运维 a chroma keying filter. Does anybody know how to get it in flex 3.

every help is welcome.

---

Here is a simple Difference Key pixel bender kernel: http://code.google.com/p/quasimondolibs/source/browse/trunk/quasimondolibs/com/quasimondo/shaders/DifferenceKey.pbk

---

Yep http://code.google.com/p/quasimondolibs/source/browse/trunk/quasimondolibs/com/quasimondo/shaders/DifferenceKey.pbk by Quasimondo is perfect. Easy to build upon as well