title: How to extend a drawn line in OpenCV?
body: <p>I have a project to create a face detection program. One of the requirements is for me to draw a line across the center of the face.</p>
  
  <p>Now the way I have done this is by first drawing a line across the two eyes (by getting each eye's coordinates and using them as line points) and then drawing a perpendicular line to that. This way I can account for face rotation aswell. </p>
  
  <p>However this line is the same length as the line across the eyes. I want this perpendicular line to cut across the entire face if possible. Attached is an example of my output for one the rotated face images. I need the green line to be longer. </p>
  
  <p><img src="https://i.stack.imgur.com/HFmzR.jpg" alt=""></p>