DEVICE FOR MEASURING AMOUNT OF NOISE

摘要

A device for measuring an amount of noise is provided to make it possible to measure the amount of noise with respect to an image input signal onto which automatic gain control is performed. A memory(12) stores an image input signal for at least one frame. A subtracting circuit(13) computes brightness level difference values for respective pixels between image signals for plural regions of the image input signal and image signals of the same regions read from the memory(12). An integral circuit(16) adds absolute values of the computed brightness level difference values for respective regions to the brightness level difference values for respective regions, thereby outputting brightness level difference sums for respective regions. If there is at least one of the brightness levels greater than the critical value in a predetermined region, a brightness determining circuit(14) outputs a detection signal for the predetermined region. A minimum value outputting circuit outputs the minimum value of brightness level difference sum as an amount of noise among the brightness level difference sums for respective regions except the predetermined region.