| 摘要 |
PURPOSE:To conduct automatic control to keep a gain of a receiving analog system circuit properly. CONSTITUTION:DSC 4 divides an image into partial areas B1-B9, and aquires central values b1-b9 of frame data corresponding to the respective partial areas to be given to an auto gain controller 10. The auto gain controller 10 compares the central values b1 b9 with a designated proper value to detect the suitableness/unsuitableness of a central value of each partial area, and when the number of partial areas, the central values of which are unsuitable, larger than a designated threshold, a gain of a receiving analog system circuit 3 is changed. Thus, the gain of the receiving analog system circuit or the gain of TGC is kept automatically properly, so that a proper image can be always seen without frequent manual adjustment. Furthermore, it is possible to prevent the diagnosing time from being elongated by manual adjustment. |
