IMAGE SENSING APPARATUS HAVING AUTOMATIC IRIS FUNCTION OF AUTOMATICALLY ADJUSTING EXPOSURE IN RESPONSE TO VIDEO SIGNAL

In a video camera having an automatic iris function and a gamma correcting function, an object evaluating value is calculated based on an exposure evaluating value in a sampling area designated as a priority area, a target luminance level for exposure control is changed according to the relation between this object evaluating value and exposure evaluating values in sampling areas other than the sampling area selected as the priority area, a ratio with which the priority area is weighted in calculating the object evaluating value is changed, and a correction value for gamma correction is further changed. As a result, overexposure and underexposure in a picture are decreased. Furthermore, if an extremely small value is included in exposure evaluating values in sampling areas, the value is previously replaced with a predetermined fixed value, so that the effect of noises or the like on exposure adjustment is decreased.