| 摘要 |
PURPOSE:To exactly detect a focal shift without being influenced by a surface state of an object to be brought to image pickup, shading, a light and shade variation of a light source, etc., by deriving a differential signal exceeding a prescribed level from the respective luminance signals which have been brought to image pickup by plural image pickup means, and comparing each counting value thereof. CONSTITUTION:The titled device is provided with plural image pickup means 13a, 13b-15a, and 15b for bringing plural patterns 12a-12d being equal to each other of an object to be brought to pickup 11, to image pickup, respectively, and converting them to luminance signals, differentiators 23a, 23b for obtaining a differential signal of the luminance signal, counters 26a, 26b for counting the differential signal whose signal level is above the first prescribed value Th1, and a comparator 27 for comparing a ratio of each counting value to plural patterns 12a-12d, and the second prescribed value. In this state, based on a result of comparison, a relative focal shift of plural image pickup means 13a, 13b-15a, and 15b and the object to be brought to image pickup 11 is detected. In this way, the focal shift can be detected exactly without being influenced by a surface state of the object to be brought to image pickup, and also, without being influenced by shading and a dark and shade variation of a light source, etc. |
