Art of Sketch - FREE by Xionghui Liu

You can give your photos a dramatic effect by converting them to sketch, while keeping the region and details that you choose in color.
How to:
1. Use your finger as a brush to "paint" area of the sketch image, or to bring back the original color.
2. Move photo by two-finger move.
3. Zooming in and out by two-finger pinching.

Add a demo circle to indicate which pixels will be changed.