Disclosed is a method 1201 of processing a video stream, the method comprising the steps of determining 1230 a representative age measure from a model for a visual element from the video stream, determining 1250 a representative activity count measure from the model, establishing a functional relationship between the representative activity count measure and the representative age measure, comparing 1240 the functional relationship to a threshold value, and determining 1260 if the visual element is stationary, based on the result of the comparing step.