Stretch image area via opencv or opengl in iOS

Question

I am trying to make a double chin in a bold image, as indicated in my desired image below.

I turned a normal face into a bold face, wrapping the image on a grid and warping the grid.

• Source image

2. Grid wrapped image with offset vertex points

3. Image of the current result

I tried a lot, setting the grid points, but could not get the result, as shown in the first image.

Any ideas how to achieve this by opening GL or opening CV in iOS?

Answer 1

The first image shows that there is an additional effect to create a double or triple chin.
It actually looks like a predefined image mixed with the original or scale, and a stretched version of the original chin mixed with the distorted image.