Contour is a plot method, therefore you don't extract data FROM it, you give data TO it. What I think your problem is, that your data grid resolution is not high enough for some reason. You can try to interpolate your grid to have a smoother contour plot. See this matlab example:

x1=0:20:90;

y1=0:0.125:0.725;

[X1,Y1]=meshgrid(x1,y1);

Z=(X1-45).^2+1D4*(Y1-0.4).^2;

figure()

contour(X1,Y1,Z);

x2=0:1:90;

y2=0:0.005:0.725;

[X2,Y2]=meshgrid(x2,y2);

Z2=interp2(X1,Y1,Z,X2,Y2,"spline");

figure()

contour(X2,Y2, Z2);