EXPOSURE CONTROLLER, EXPOSURE CONTROL METHOD AND IMAGE PICKUP DEVICE

摘要

PURPOSE: To always provide proper exposure by controlling a diaphragm means based on the luminance level of a picture element having the chrominance information of a high saturation degree among image data fetched into an image memory regardlessly of the lightness of the background of an object. ;CONSTITUTION: Inside a diaphragm control signal processing circuit 12, it is decided whether a saturation degree S concerning each picture element exceeds a threshold value ε or not. When the luminance level of a picture is high like back light, the luminance values of all the picture elements, whose saturation degree S exceeds the threshold value ε, are integrated and normalized. When the normalized integrated value is compared with a reference value, it is larger than the reference value. Therefore, a diaphragm control signal 9 for further closing the diaphragm of a lens is outputted and an iris 4 is controlled. When the luminance level is low like intensive follow light, the luminance values of all the picture elements, whose saturation degree S exceeds the threshold value ε, are integrated and normalized. When the normalized integrated value is compared with a reference value, it is smaller than the reference value. Therefore, the signal 9 for opening the diaphragm of the lens is outputted to an iris motor 13 and the iris 4 of a lens block 2 is controlled.;COPYRIGHT: (C)1996,JPO