The principle of high-definition fog-penetrating integrated movement technology

In recent years, with the rapid development of cities, a series of environmental pollution has been brought about, such as automobile exhaust, industrial emissions, construction dust, slag burning, etc. The mixture of these pollution sources constitutes "smog weather". In hazy weather, the color of the images monitored by most video surveillance systems will be dim and the contrast will be lower, which will cause some important details to be swallowed up in the fog and difficult to find, which will lead to video surveillance systems. Normal functioning is affected. Although the smog is so serious, you may not be able to find your way home when you walk in the cold wind, but why is the traffic e system still generating revenue? This question puzzles many drivers. Therefore, today, the editor will take you to take a look at this black technology product of the traffic - the fog-penetrating camera. 1. The fog-penetrating principle of fog-penetrating camera Natural light is composed of light waves with different wavelengths. The visible range of the human eye is roughly 390nm-780nm. The wavelengths from long to short correspond to seven colors of red, orange, blue, green, green, orange, and purple. Among them, the wavelengths less than 390nm are called ultraviolet rays, and those with wavelengths greater than 780nm are called ultraviolet rays. called infrared. The small particles in the air such as fog and smoke have a blocking effect on the light, so that the light cannot be reflected and cannot pass through. Therefore, the human eye that can only receive visible light cannot see the object behind the smoke and fog. The longer the wavelength, the stronger the diffraction ability, that is, the stronger the ability to bypass obstructions, while the infrared rays are less affected by aerosols during propagation due to their longer wavelengths, and can pass through a certain concentration of fog and dust to achieve precise focusing. , which is the basis for optical fog penetration. Three elements to complete the fog: In the range of invisible light, light of a certain frequency can penetrate fog, but due to the different starting wavelengths, it needs to be processed on the camera to achieve the purpose of focusing on it, and it is also necessary to redesign the camera to use Stop imaging the invisible light of this frequency. Since this invisible light has no corresponding visible light color map, the image presented on the monitor is black and white. (1) Lenses with chromatic aberration compensation In order to get a better fog penetration effect, the design of the lens is very important. In order to ensure that the visible light imaging system can obtain ideal images before and after the fog is passed through, the lens must ensure high transmittance in the visible light and near-infrared bands, and the chromatic aberration correction is stopped during the switching of the two bands to ensure that no further changes are required after switching. Adjust the focal length. The central wavelength of the transmission spectrum of ordinary lenses is between 500 and 600 m, and the lens in the fog-transmitting system needs to have high transmittance at 500 to 600 nm and 780 to 900 nm. Therefore, the lens adopts multi-layer coating technology. The transmittance of the lens in the 500-900 nm band is all greater than 80%. In principle, the wider the applicable near-infrared band, the better, but limited by the difficulty of the optical path design of the lens and the light-sensing ability of the CCD, the longest infrared band known to be applicable to the lens in the security industry is 1100nm. (2) CCD with high near-infrared flexibility The spectrum from the visible light band to the near-infrared band has a good frequency response curve. The ultra-flexible CCD camera is a necessary condition for an excellent system, so that only one camera can reach the visible light band and the near-red band by changing the filter. The separate use of the visible light band to improve the clarity of the image and the use of the near-infrared band to penetrate the mist to increase the viewing distance. (3) Image processing of black level stretching The scattering of water vapor and solid particles over oceans and cities results in flat, gray and white colors in the distance within the visible interval. Long-distance imaging cannot exceed the visible interval. The use of filters undoubtedly plays a significant role, but it is necessary to Reach people's application requirements for viewing images from a distance, the clearer the better, and the farther the distance, the better. It is necessary to use electronic processing technology to further filter out the gray-white film-like interference signal caused by scattering, and then process the useful white light or black and white signal, so as to obtain excellent image signals of distant objects. Second, the fog penetration technology is mainly divided into four types: Optical fog Ordinary visible light cannot penetrate clouds and smoke, but near-infrared rays can penetrate a certain concentration of fog and smoke. Optical fog penetration applies the principle that near-infrared rays can diffract tiny particles to achieve precise and fast focusing. The key to the technology is mainly in the lens and filter. Through the physical method, the principle of optical imaging is applied to improve the clarity of the picture. The disadvantage is that only black and white monitoring pictures can be obtained. Algorithm through fog Algorithmic fog penetration technology, also known as video image anti-reflection technology, generally refers to clearing the hazy image caused by fog, water vapor and dust, emphasizing some interesting features in the image, and suppressing uninteresting features. The quality of the image is improved, and the amount of information is enhanced. Photoelectricity through fog Photoelectric fog penetration is to separate the above two functions, through the integration of the movement, through the embedded FPGA chip and ISP/DSP processing processing to complete the color image output. On the one hand, this fog-penetrating technology can distinguish factors such as long-range, close-range, and fog density. Selecting the fog-penetrating level can achieve the best regional effect, which is different from the overall improvement of the picture contrast in the past, and there is no delay. On the other hand, the high-speed operation of the chip will inevitably generate noise points, especially when the light is lacking at night, so the integrated movement generally needs to use a CCD sensor and a large aperture lens to achieve a good low-light effect. It is currently the best technology for fog penetration on the market. fake fog This is mainly by artificially adjusting the values ​​of contrast, sharpness, saturation, brightness, etc., or by switching and installing some filters, so that the image focus is highlighted, thereby improving the objective visual effect. The disadvantage is that it cannot refocus on the scene, and it is difficult to satisfy the visual experience. 3. Conclusion With the development of industry and its impact on climate, smog has increasingly become a common weather phenomenon, which has a great impact on the picture quality of monitoring systems used in outdoor applications. The defogging technology can improve the quality of video surveillance from multiple angles, and can be used for fog treatment in various foggy weather conditions; it can significantly improve the contrast of the image, make the image transparent and clear; it can significantly enhance the image quality. Detail information, so that the original hidden image details are fully displayed; it can enhance the saturation of the image, make the image color bright and vivid, and the image after the fogging treatment maintains accurate color and natural appearance, so a good image is obtained. quality and visual perception.