I = imread('ht_test.tif');

im = double(I);
BW = edge(im,'canny'); 
subplot(1,2,2)
imshow(BW)

[acc,T,R] = hough(BW, 'ThetaResolution', 1, 'RhoResolution', 1);

subplot(1,2,1)
imshow(log(acc+1), [], 'XData', T, 'YData', R, 'InitialMagnification','fit');
xlabel('\theta'), ylabel('\rho'); axis on, axis normal;

P  = houghpeaks(acc, 15, 'Threshold', 0.25*max(acc(:)) );

[xs ys] = size(BW);

theta = T(P(:,2));   
s     = R(P(:,1));            

sprintf('# of lines found: %d', size(P,1))

for i=1:size(P,1)
    subplot(1,2,1)
    hold on
    plot(theta(i), s(i), 's', 'color', 'red');
    hold off
  
    subplot(1,2,2);
    hold on
    ht_plot( theta(i), s(i), xs, ys );
    hold off
    
    pause
end