title: Area of interest and Hough Line Detection for distorted lines accuracy
body: <p>I am trying to do segmentation of book spines stacked both horizontal and vertically. I have came across a problem when the picture is too big.
  <img src="https://i.stack.imgur.com/1koxD.gif" alt="enter image description here"></p>
  
  <p>Only part of the image can be seen in the whole window, meaning it does not process the original image it is suppose to process:</p>
  
  <p><img src="https://i.stack.imgur.com/Skqt4.gif" alt="enter image description here"></p>
  
  <p>The image it processed
  <img src="https://i.stack.imgur.com/Gxp3U.gif" alt="enter image description here"></p>
  
  <p>The image it should process instead
  <img src="https://i.stack.imgur.com/OpNhq.gif" alt="enter image description here"></p>
  
  <p>I cannot even view the whole image which is suppose to be processed. Hence, I tried to minimise the window just for this picture using=></p>
  
  <p>cv::resize(image, image, cv::Size2i(image.cols/6, image.rows/6) ); // resize to 1/6 of the image</p>
  
  <p>which lead to another problem, when the picture is small, it become too small that the straight lines cannot even be detected.</p>
  
  <p>Hence, I tried =>
  cv::resize(image, image, cv::Size2i(750, 400) );</p>
  
  <p>this lead to another problem. While the image above is above to display the whole window, for smaller pictures, my houghline detection becomes more unstable. </p>
  
  <p><img src="https://i.stack.imgur.com/JTsRI.gif" alt="enter image description here">
  <img src="https://i.stack.imgur.com/OEtti.gif" alt="enter image description here"></p>
  
  <p>Do anybody have an idea on how to solve this sizing problem? And also how to improve my Hough Line detection which is pretty unstable now to separate the books? I wish to draw a line in between the stack of books.</p>
  
  <p>Hope to hear from you guys soon. Thanks!!! </p>