For calculating area

I used the spine function to make the region. Is there way I can calculate the area of this region?

Here is my code.

figure, imshow('ac21sag.png')
hold on
xy = [];
n = 0;
but = 1;
while but == 1
    [xi,yi,but] = ginput(1);
    plot(xi,yi,'ro')
    n = n+1;
    xy(:,n) = [xi;yi];
end
t = 1:n;
ts = 1: 0.1: n;
xys = spline(t,xy,ts);
plot(xys(1,:),xys(2,:),'r-');
hold off

Answer 1

[Jonathan Sullivan]

polyarea

 A = polyarea(xys(1,:),xys(2,:));