1. A device comprising: a controller; a memory coupled to the controller; and an input interface arranged to receive at least first and second event signals; wherein the controller is configured to: determine an estimated value of at least the first event signal using a transform function and the second event signal; determine a deviation between the estimated value and the first event signal, compare the deviation with a pre-determined threshold value, and determine whether an artifact is present in at least the first event signal in accordance with the comparison of the deviation and the pre-determined threshold value.