How to relocate face points in opencv / face distortion

Question

I have to simulate facial expressions on a face image ( say open mouth ). For this I first extracted the facial feature points and found the corners of the lips. Now I need to deform the image by moving the points down.

In the above image I need to move the points ( 2 ) and ( 3 ) to some distance left and right respectively. And point ( 18 ) and ( 19 ) littele bit down. So that I will get an expression like opened mouth.

My Questions:

1) Is this the above way right to proceed to simulate facial expression?

2) If it is right how to move the points and create a new image in opencv?

Answer 1

A fairly recent survey and course of techniques people have used in this area is here: http://old.siggraph.org/publications/2006cn/course30.pdf

TL:DR. There is no "right" way to do it, in any absolute sense. You need to define your goal in a way that is computable. Then figure out what additional (prior) information you need to reach it, in addition to the image data themselves. Fiddling with "texture warping" or other interpolation schemes before you decide what you need to do is a waste of time.

You mention "an expression like an opened mouth", and I interpret that to mean that you'd like to produce an image similar to what the real face would look like if the subject had been photographed with their mouth open. The markers you found obviously do not give enough information about that - in particular, they do not express any notion of "mouth". In fact, that notion is nowhere to be found in the image. So, strictly speaking, your task is unsolvable unless you throw more information into it.

I suggest you take a look at the paper pointed above, and rethink your problem again.