doodling passengers on a plane

On a four hour flight and on a break from reading I decided to do a quick sketch of a guy in front of me on the plane. 

The fun thing about ipad drawing is that you can play with the image using a variety of filters. Before anybody bemoans that using filters is cheating, the bottom line is that no amount of filters are going to rescue a bad photograph or drawing. 

Unfortunately after doing the original sketch on profingersketch and importanting to procreate I can't remember the sequence of filters or drawing tweaks. I don't follow one particular pattern/filter to come up with the final result.

Here is the original drawing.