1. A non-transitory machine readable storage medium encoded with computer program code, such that when the computer program code is executed by a processor, the processor performs the operations of: forming respective wafer fingerprints by selecting a respective object of one or more objects in a respective wafer map of a plurality of wafer maps; determining a respective feature in each of the respective wafer maps using the respective selected object, classifying a respective pattern for each of the respective wafer maps using the respective determined feature and stored pattern information, and identifying a semiconductor wafer fabrication process or tool to be adjusted using the respective wafer fingerprints formed for each of the plurality of wafer maps.