In recent years, CMOS image sensors have been widely applied to various image capturing devices, e.g., a digital picture camera, a digital video camera, a mobile phone, etc. Due to different photo-electric conversion time of respective pixels or rows of pixels in the course of photo-electric conversion, there may be bright and dark horizontal strips in a captured image, especially in the case that the image is captured under fluorescent lighting or some other lighting condition with periodically changing brightness. Such a horizontal stripe in the captured image arising from periodically changing lighting is referred to “flicker”.
An exposure period of time can be set reasonably dependent upon the frequency of flicker to suppress and even eliminate flicker in the captured image. This necessitates the detection of the presence of flicker and the frequency of flicker.
Traditional method of detecting the presence of flicker and the frequency of flicker suffer from the disadvantages of poor detection accuracy, a low detectable rate and being subjected to a considerable influence from motion in a sequence of image frames.
Thus, there is a need of a flicker detection method and a flicker detection apparatus capable of detecting flicker in a sequence of image frames efficiently and accurately and further capable of being subjected to an inconsiderable influence from motion in the sequence of image frames.