1. A method of operation for vision-based occupant classification in a vehicle cabin, comprising the steps of: producing a series of digital images of a region of said cabin that includes a vehicle seat; executing a static classification routine that processes the produced digital images to detect and classify an occupant of said seat; once said static classification routine has detected and classified the occupant of said seat, suspending further execution of said static classification routine, and instead executing a dynamic detection routine that processes the produced digital images to detect a change in position of the detected occupant; executing a category state change routine following the suspension of said static classification routine for detecting a potential change in an occupant category of said seat; and if said potential change in occupant category is detected by said category state change routine, suspending further execution of said dynamic detection routine and said category state change routine, and instead re-executing said static classification routine to re-detect and re-classify the occupant of said seat.