function [XC,YC,R] = locatecenter(IMAGE,TOL,NPTS)
F = imread(IMAGE);
FG = rgb2gray(F);
[DY,DX] = size(FG);
XC = 0;
YC = 0;
K = 0;
for J = 1:DX
    for I = 1:DY
        if (F(I,J) <= TOL)
            XC = XC + J;
            YC = YC + I;
            K = K + 1;
        end;
    end;
end;
XC = uint8(XC/K);
YC = uint8(YC/K);
I = 0;
while F(YC+I,XC)-F(YC,XC) <= TOL
    I = I + 1;
end
R = I;
THETA = linspace(0.0,2.0*pi,NPTS);
X = 0.1*R*cos(THETA)+double(XC);
Y = 0.1*R*sin(THETA)+double(YC);
imshow(F);
hold on;
plot(X,Y,'y-');
X = R*sin(THETA)+double(XC);
Y = R*cos(THETA)+double(YC);
plot(X,Y,'r-');
end