Pop Art.

Pop art attempt with Miley Cyrus, going from her young years to recent, Britney Spears, from now to her first album Baby One More Time, and Avril Lavigne, from Sk8er Boi, to Best Damn Thing, to Goodbye Lullaby.

For Miley I used a threshold and replaced the color. I also added a gradient in the background with circle pixels.
For Britney I used a comic book effect.
For Avril I used different effects the changed the opacity of certain layers and saturated the pictures as well as posterized

Some of the pictures didn't look good with certain effects, so I had to do quite a bit of adjusting.