An image-based method and corresponding apparatus for measuring, in scientifically basic terms, the complete fiber length distribution from a tapered beard. An intensive target throttle angle is computed based on the running state of the engine, regardless of a combustion mode which is underway. If this number exceeds a first threshold, the datagram is discarded. Oxygen ions are implanted into the metal layer in one active area to form an implanted metal layer which is oxidized to form a metal oxide layer.