1. A method of capacitive sensing, comprising: obtaining, from a plurality of sensor electrodes, a first capacitive image of a sensing region; identifying an object signal value within the first capacitive image, wherein the object signal value is identified from a first object response that is produced by an input object that is proximate to the plurality of sensor electrodes; determining, using the object signal value of the first object response, an artifact threshold that identifies a first artifact response within the first capacitive image, wherein determining the artifact threshold comprises: determining a maximum signal amplitude of the first object response, and designating the artifact threshold as a proportion of the maximum signal amplitude; determining a plurality of capacitive responses within the first capacitive image; determining, using the artifact threshold, which of the plurality of capacitive responses are artifact responses; and excluding one or more of the artifact responses from a first report to a computing system.