The sensor forms an image and OpenCV detects the actual touch configuration. It appears you can use the raw data from the Arduino, too, but it might be a little harder.

A recent ACM paper shows how just about any capacitive sensor can work as a multitouch sensor with nothing more than an Arduino although a PC running processing interprets the data for higher ...

The EasyTouch capacitive touch sensor can be used with either the Arduino platform or the Raspberry Pi mini PC using the EasyPlug breakout board if required.