A Research Method Of Smart Phone Fast Detection And Shooting Lightning Scenes

Smartphone are quite common in everyday life because of its compact, easy to carry and increasingly powerful camera features. Throughout smart camera phones at home and abroad, the major business make the appropriate upgrade and improve its performance to meet the basic outdoor scenery pictures, portrait, macro, or indoor light does not require enough shooting situations on the camera resolution, screen resolution and focus, continuous shooting, color and other features. But smartphone can not shoot satisfactory night as lightning and other special scene. A mobile phone company proposed the solutions to the needs of the smart phone to detect and shoot lightning in order to increase the selling point.Based on smartphone CMOS imaging technology, we build an experimental platform to simulate lightning smartphones. Because of smart phones and camera already highly integrated, it is difficult to control under current experimental conditions. Therefore, in the laboratory we choose CMOS industrial camera with motorized lens as an experimental platform, and use simulation lightning flash. Among them, the industrial cameras complete the automatic detection and exposure functions and motorized lens complete the autofocus function. The experimental platform for detection and imaging methods have been well verified, to achieve lightning fast detection and shooting purposes. Specific studies are as follows:First of all, lightning fast detection is based on image camera video stream. Two adjacent gradation frame image make difference operation processing and do take the absolute value. If lightning signal value after the removal of the background exceeds the set threshold, this reached lightning detection purposes;Secondly, the autofocus lens is achieved by three variable electric. Lightning shooting scenes can be regarded as actual infinity. At a fixed aperture and focal length, the lens focus infinity first to improve focus speed and then fine-tuning. The lens tuning through AF algorithm and auto-focus algorithm include image sharpness evaluation and pole search algorithm. This article briefly describes the purpose of several image clarity evaluation function and compare its performance to select a good performance evaluation methods to achieve autofocus combining pole fast search algorithm;Finally, automatic exposure control the camera exposure time. Due to the night scene being recorded, the camera use a smaller gain control value to prevent too much noise. Firstly, the automatic exposure control is determined by image based on ambient light conditions to determine the AE target luminance value of the target image. For lightning fleeting characteristics, selection algorithm is based on look-up table of the automatic exposure. Exposure-related parameters will be calculated in advance is stored in a table. Based on the brightness values look-up table it obtain directly previous frame image in the exposure calculation process and calculate the exposure value corresponding to the next frame possessing exposure lightning images, and get the exposure in lightning scenario.