There’s an Adobe pdf converter iPhone camera app that will center them as perfect scan like images.
It's already included in your phone. Hold down your Notes icon, a menu will pop up, "Scan Document" and just point your camera at the page. It's crazy easy, you're welcome.
I just did this in 2 minutes, but didn't have very good lighting:
Super handy thing to know if you have to send a document to someone but you only have your phone on you.