Cloak Effect - Where do I even start?

I want to create a cloaking effect in my game like off the film “Predator” or like the infiltrator from PlanetSide 2…

I’m using Slick2D as my framework. Do I use a shader? Pixel manipulation? I have no idea…

http://iridar.net/wp-content/uploads/2016/06/20111118_4ec6f04249c20.jpg

Here’s an example of the effect I’d like.