A method and apparatus for setting or modifying a programmable operating parameter associated with a power driven wheelchair is provided. The apparatus has an accessing tool for accessing the patient region, the tool having a distal end, and a proximal end at which the tool can be manipulated to place the distal end adjacent to the patient region. The reduced image reflectance component calculating unit calculates a reflectance component indicating a ratio of brightness between each pixel and the peripheral pixels thereof for the each pixel in the reduced image.