How to take a screenshot from a matrix

I have a jit matrix receiving input from my webcam. I am trying to find a way that I could grab one frame from this webcam and send it to another matrix. I'm trying to create a "freeze frame" in a separate matrix while the webcam continues in the main window.

I've been trying to work with toggles and bangs and all that, but I think I am going about this wrong. In my head, it makes sense to use a gate, but I can't seem to get it to work. I don't really have a patch to show, because I don't even know how to go about this...