How do I align a face for preprocessing

1. What is alignment in face recognition?
2. Why do we need face alignment?
3. How to precisely align face in Python with OpenCV and dlib?

What is alignment in face recognition?

Face Alignment is the technique in which the image of the person is rotated according to the angle of the eyes. This technique is actually used as a part of the pipeline process in which facial detection is done using the image.

Why do we need face alignment?

Face alignment is a computer vision technology for identifying the geometric structure of human faces in digital images. Given the location and size of a face, it automatically determines the shape of the face components such as eyes and nose.

How to precisely align face in Python with OpenCV and dlib?

Make a triangle using nose and eyes coordinates, find the median of this triangle. Face detection. Get the coordinates of the centre of a top side of a face rectangle (center of a top side). Make a second triangle using the coordinates of the end of the median, nose coordinates and center of top side coordinates.