function plotface(sig,Lim)
    figure; hold on
    [N T] = size(sig);
    v = [1:T];
    for i = 1:N,
        subplot (N,1, i);
        fa=sig(i,:);
        I=reshape(fa,28,23);
        imshow(I,[min(I(:)) max(I(:))]);
        %imshow(I);
        %plot(v,sig(i,:));
        if nargin > 1
            set(gca,'YLim',Lim);
        end
    end
return;