title: How to detect lines using houghlines on the actual image rather than in the hough graph
body: <p>I want to detect lines in a text document. Here is the <a href="http://imgur.com/styPieg" rel="nofollow">original image</a> this was eroded to make the task of edge detection easier using the <code>erode</code> function. Here is the <a href="http://imgur.com/CBjI5hv" rel="nofollow">eroded image</a>.</p>
  
  <p>Now to detect the lines I used <code>houghlines</code>, and used the following code in my script file.</p>
  
  <pre><code>I  = imread('c:\new.jpg');
  rotI = imrotate(I,33,'crop');
  bw_I = rgb2gray(rotI);
  BW = edge(bw_I,'canny');
  [H,T,R] = hough(BW);
  imshow(H,[],'XData',T,'YData',R,...
              'InitialMagnification','fit');
  xlabel('\theta'), ylabel('\rho');
  axis on, axis normal, hold on;
  P  = houghpeaks(H,5,'threshold',ceil(0.3*max(H(:))));
  x = T(P(:,2)); y = R(P(:,1));
  plot(x,y,'s','color','white');
  % Find lines and plot them
  lines = houghlines(BW,T,R,P,'FillGap',5,'MinLength',7);
  figure, imshow(rotI), hold on
  max_len = 0;
  for k = 1:length(lines)
     xy = [lines(k).point1; lines(k).point2];
     plot(xy(:,1),xy(:,2),'LineWidth',2,'Color','green');
  
     % Plot beginnings and ends of lines
     plot(xy(1,1),xy(1,2),'x','LineWidth',2,'Color','yellow');
     plot(xy(2,1),xy(2,2),'x','LineWidth',2,'Color','red');
  
     % Determine the endpoints of the longest line segment
     len = norm(lines(k).point1 - lines(k).point2);
     if ( len &gt; max_len)
        max_len = len;
        xy_long = xy;
     end
  end
  
  % highlight the longest line segment
  plot(xy_long(:,1),xy_long(:,2),'LineWidth',2,'Color','blue');
  </code></pre>
  
  <p>This produced <a href="http://imgur.com/8kYDjuM" rel="nofollow">this result</a>. Now I know that the intersecting points are the detected lines. What I want is to somehow show these lines detected onto the original image such as highlighting lines or underlining them. Is this possible? Which function would I use for that?</p>
  
  <p>edit: What I wanted to say was that how do I translate the detected lines( intersecting points) from the last result to a more clearer result. </p>