How can I Connect camera circuit with arduino circuit ?(simulink)

I finished my color detection circuit with simulink (microsoft usb web cam) and now I want to connect the out put to the arduino mega 2560. for example, when red color detect LED light which connected to arduino will turn on.

do I need USB shield? how can i solve the problem?

i attached 3 pics 1- my color detection circuit with normal mode(no error) 2- my color detection circuit with normal mode connceted to arduino pin 9 (no error) 3- my color detection circuit with external mode connceted to arduino pin 9 (error)