LIGHTING-CHANGE COMPENSATOR

摘要

PURPOSE: To compensate the variation of an image signal due to the illuminance change of an object by comparing the picture signal level of the object with a logical picture signal level and adjusting the amplitude of the image signal. CONSTITUTION: The image signal level of the object is compared with the logical image signal level and a microprocessor 50 controls an image signal preprocessor circuit 35 to change the amplitude of the image signal based on one of two references in accordance with judgment whether prescribed relation between the image signal level of the object and the logical image signal exists or not. When the prescribed relation exists, the amplitude of the image signal is adjusted until the signal level of a background and the signal level of the object respectively correspond to prescribed values. When the prescribed signal level relation does not exist, the amplitude of the image signal is adjusted until a difference between the image signal level of the background and the logical image signal level of the object becomes equal to a prescribed value. Consequently the variation of the image signal due to the temporary change of illumination intensity for a taken scene is compensated.