This app comes from Yahoo Japan. The app works by masking your face using a provided photo of... anything, like a celebrity or an animal. You can then upload your cat-face on social network. Simply select one of the premade masks or make your own with he provided tools.
The app tracks facial feature points, like this. It captures the movements of these feature points, in synch with the motion of your mouth and eyebrows. So it can change how your face looks by synthesizing the mask picture accordingly. A feature of this application is that it tracks in real time, even on a smartphone. We think there aren't many apps that can track facial feature points using just the processing power of a smartphone.
This can track your face even if you vary the angle a lot. It even tracks unusual expressions, so it's fun to make all sorts of expressions with your mouth.