Flicker detection in a video imaging device

摘要

A method of detecting lighting flicker in the output of a video imaging device, and video imaging devices adapted to implement the method. The video imaging device has a main picture area divided into pixels and producing successive images at a frame rate. The method comprises producing a series of signals from at least one additional picture area adjacent the main picture area, the additional picture area having a size substantially larger than a pixel. Each of the signals is a function of light incident on the additional picture area in a time period substantially shorter than that of the frame rate. Predetermined numbers of said signals are accumulated to form a series of compound samples and the compound samples are filtered to detect components indicative of flicker, using a bandpass filter tuned to the nominal flicker frequency. The compound samples are formed at a sample rate which is a multiple of the nominal flicker frequency, and said filtering is effected by taking the fundamental output component of a radix-N butterfly.