Adding image compare element to portfolio single image style

In the process of adding new portfolio we described here:

http://knb.owwwlab.com/owwwlab-support/adding-portfolio-item/

you can add these steps to have your images compared.

This tutorial aims to build the section that compare two images within portfolio single image style which you can see here:  http://demo.owwwlab.com/wp-toranj-demo3/?owlabpfl=portfolio-1