Detecting a tool used on a touch screen

An electronic system comprising:

• a capacitive touch sensing device;
• a processor coupled to said capacitive touch sensing device;
• a memory coupled to said processor, wherein said electronic system is configured to:
• access a cell value for each cell of said touch sensing device, wherein said cell value indicates a force applied to said cell;
• determine a touch area sample count as a count of how many of said cells have a cell value above a noise floor;
• determine a touch area weight as a sum of all cell values for said cells having a cell value above a said noise floor;
• and
• identify an object touching said touch sensing device based on said touch area sample count and said touch area weight.

An article of manufacture including a non-transitory computer readable medium having instructions stored thereon that, responsive to execution by an electronic system, cause said electronic system to perform operations comprising:

• accessing a cell value for each cell of a touch screen, wherein said cell value indicates a force applied to said cell;
• determining a touch area sample count as a count of how many of said cells have a cell value above a noise floor;
• determining a touch area weight as a sum of all cell values for said cells having a cell value above a said noise floor;
• and
• identifying an object touching said touch screen based on said touch area sample count and said touch area weight.