Question about resizing and cropping

edit

https://snag.gy/DOdZBc.jpg

First: I have an image that I want to adjust the resolution of to a set resolution with a desired scale to ratio around the head..

currently i have this going

widthO, heightO = image.shape[:2] ## original width and height
image = cv2.resize(image,(2170, 2894), interpolation = cv2.INTER_AREA)
new_dimensionX = heightO * 631 / ((pointOfEight)  - (pointOfInterestX))
new_dimensionY = widthO * 631 / ((pointOfEight) - (pointOfInterestX ))
image = cv2.resize(image,(int(new_dimensionX), int(new_dimensionY))

I need the head to be with the height of 631. I'd like to maintain the 2170,2894 size on the last calculation. Any help?

Also, on that note. Once that occurs, I can calculate those three dots. And I want to center the image based on the middle dot such that the nose will have a straight line going vertically through it at the center.

This is my attempt:

Rx = new_dimensionX / heightO
Ry = new_dimensionY / widthO
crop_img = crop_img[0:2894,  int((pointOfNose  - 2170/2) * Ry):int(pointOfNose  + 2170/2 * Ry)]