title: Finding Pose variation of a face using Opencv
body: <p>In an image there is a face, which is tilted a bit and has a slight pose variation. Using opencv i detected the co-ordinates of eyes, nose, and mouth. Using these 4 points is it possible to re-align this face into an ideal frontal face ? 
  I tried out perspective transformation, which did work for a few images, but gave horrible results for most of the pics. Is there any other way of re-aligning the image into an ideal frontal face without any tilt or pose variation? </p>