How to align face images c++ opencv

Question

I am developing a C++ application for face authentication. First, I have to detect the face and pre-process the image.

1. For face detection I have used the HaarC

Answer 1

Have a look at CSIRO face analysis SDK (website and demos, source code) software, it does face alignment, tracking with 66 fiducial points. It is fast and very accurate.

Answer 2

The state-of-the-art approach for face alignment must be this:

Supervised Descent Method and its Application to Face Alignment X. Xiong and F. De la Torre in CVPR 2013

It is extremely fast and effective. You can check their project website IntraFace.

They provide an easy-to-use software. However, the core part code, i.e supervised descent method (SDM) is not released, it is only simple linear regression which can be easily implemented.

A demo to show that it can handle tilted face is here (for privacy issue, add blur and pay attention to the axis in the top-left corner): https://drive.google.com/file/d/0BztytuqPViMoTG9QaEpZWi1NMGc/edit?usp=sharing

Answer 3

Can't you then use another Haar classifier to find each eye (eyes are very easy to find) then assuming the person has two eyes and we define a 'level' face to mean the eyes are horizontal.

Simply measure the anlge between the two eyes and rotate the image by that angle.

angle = atan ( eye1.Y - eye2.Y ) / (eye1.X - eye2.X )