1. A method comprising: determining, with a processor, a number of preceding, consecutive frames during which a filtered value has been greater than a current value of a current frame or the number of preceding, consecutive frames during which the filtered value has been less than the current value of the current frame; determining a weight based upon the number of preceding, consecutive frames, wherein the weight varies in a direct relationship to the number of preceding, consecutive frames; and determining a filtered value of the current frame based upon a combination of the weight and a difference between a prior filtered value and the current value of the current frame.