Photochromic materials comprising indeno-fused naphthopyrans having substituents comprising a 4-fluorophenyl group and a 4-aminophenyl group bonded to the 3-position of the indeno-fused naphthopyran are disclosed. A memory stores a standard angle and a comparison distance corresponding to the scanning angle. The hidden program is being updated dynamically to strengthen it against reverse engineering efforts. This method can provide smooth startup andor restart at any speed.