Working in the style of Lichtenstein

In my spare time I like to do a few digital designs to help me progress my skills on illustrator.
I have recently been browsing on my Smart Phone at a range of Photo Editing Apps.
I came across an advanced editing app which I can't remember the name of but it had a range of different art techniques which I thought would interesting to try.
Recently, I have been going through a faze of being a little obsessed with Johnny Depp. So, I took an old image of him and changed the contrast and brightness of it to make it look darker.
I then took that image and found the perfect effect that gave it a Roy Liechtenstein feel about it of the dots on the face.
For my first attempt, I am really pleased with how it looks!