I have two graphs(x-axis signal length & y-axis amplitude) of signals,,, how to calculate its mean square error from graph??

I have two graphs of different signal (x-axis signal length & y-axis amplitude).First graph has two curves that is original and recovered signal.Similarly , second graph has two curves. how to calculate its mean square error from graph??I have two graphs(x-axis signal length & y-axis amplitude) of signals,,, how to calculate its mean square error from graph??