| 摘要 |
PURPOSE:To exactly execute recognition, by varying in order a threshold level in case of electrically processing a photographic image of an object to be recognized, to a value decided in advance, also statistically processing a signal quantity of the object to be recognized, and varying a reference value of said threshold level. CONSTITUTION:When recognition has become impossible due to variation of brightness of a photographic image of an object to be recognized 1, an NG signal is outputted to a threshold value control part 8. The threshold level control part 8 selects a threshold level in order as theta+DELTAtheta, theta-DELTAtheta, theta+DELTA2theta, and theta-DELTA2theta from theta. Also, a level of a signal recognized in case of repeated recognition is processed statistically in a reference control part 9, its distributing state is detected, a center value of its distribution is compared with the threshold level theta which is used at present, a definite value of the threshold level theta is made to conform with said center value, and a range which can be covered by each threshold level can always be held in an effective state. As a result, the recognition is executed exactly, and also the work efficiency is improved. |
