| 摘要 |
PURPOSE:To enable auto-focusing even in case of an integral value smaller than a certain value by performing auto-focusing in a focus zone where the integral value is maximum and the image length is maximum when the integral value of the number of times of polarity inversion at the time of binarization the output signal of an image sensor with a prescribed binarization level is smaller than the certain value. CONSTITUTION:The output signal of an image sensor 56 is compared with a binarization level (a) for negative and a binarization level (b) for positive, and numbers of times of polarity inversion for binarization levels (a) and (b) are integrated independently of each other and the image length is integrated. When these numbers of times of polarity inversion are smaller than certain values, these numbers of times of polarity inversion and the image length are stored together with the focus zone position and the focus zone is switched to repeat this operation. If numbers of times of polarity inversion in all focus zones are smaller than certain values, the focus zone where they are maximum is obtained; and the image sensor 56 is returned to the obtained focus zone, where the image length is maximum, to perform auto-focusing when plural focus zones are obtained. Thus, auto-focusing is possible even though numbers of times of inversion in all focus zones are smaller than certain values. |
