Wide dynamic

Digital wide dynamic does not achieve the real purpose of expanding the dynamic range of imaging, but improves the contrast of local area through the image post-processing algorithm of software, which is generally realized by the camera ISP module. The range of gray scale that can be distinguished by the naked eye is very limited, but in fact, the computer can distinguish very weak gray differences. Digital wide dynamic enhances these weak differences to the naked eye through image processing algorithm. Then, based on the CCD hardware technology, the dual frame synthesis wide dynamic appears. The solution is to use a CCD, but each point above is exposed twice in a single time, a long exposure (low shutter) and a short exposure (high shutter).

Therefore, there are two data outputs at each point, which is called “dual output CCD”. Using the special image processing algorithm of DSP, the parts with appropriate brightness in the two images are cut respectively, and finally superimposed and synthesized to output an image with clear light and dark areas. Whether it is digital wide dynamic or double shutter wide dynamic, its wide dynamic effect is not ideal.

With the evolution of DSP and CMOS technology, DPS adopts the independent exposure and control technology of each pixel, combined with the linear superposition of multiple frames collected by CMOS sensor to synthesize a complete image, which has a higher dynamic range than the two exposure imaging of CCD. Numerically speaking, the dynamic range of CMOS camera with DPS technology can reach 120dB or even 140dB according to the current processing technology. Wide dynamic technology has become an important index to measure the performance of a camera. At present, the standard wide dynamic function has become the consensus of IPC manufacturers.

Fog penetration

With the deterioration of domestic haze weather environment in recent years, the market has a strong demand for fog penetrating cameras. Because the optical fog penetrating lens is relatively expensive, in order to reduce the value of fog penetrating cameras and achieve better fog penetrating effect, mainstream IPC manufacturers have begun to study the fog penetrating algorithm technology of camera video images, The haze free region can be restored according to the haze concentration of the haze model, and the haze free region can be formed according to the haze physical algorithm. The fog penetration algorithm can preserve the original color of the image and greatly improve the fog penetration effect of the image.

Intelligent analysis

HD webcam has developed from two or three intelligent analysis functions such as motion detection and video occlusion launched in 2011 to today. Almost all mainstream manufacturers have more than 10 standard intelligent functions for HD webcam. Of course, at present, most of these standard intelligent functions are only limited to medium and high-end industry products. According to market business applications, these intelligent analysis functions can be divided into the following points:

1. Diagnostic intelligent analysis. The diagnostic intelligent analysis of HD webcam is mainly to accurately analyze, judge and alarm the common camera faults such as black screen, blur, PTZ out of control, picture freezing and video signal interference such as scene change and items left / disappeared. Diagnostic intelligent analysis technology is relatively simple to implement. Usually, these intelligent functions are integrated in the front end. Of course, the back end such as NVR also has similar diagnostic intelligent functions.

2. Identification intelligent analysis. This technology of HD webcam is biased towards the analysis and processing of static scenes. Through core technologies such as image recognition, image comparison and pattern matching, it can extract and analyze relevant feature information such as people, vehicles and objects. In the application of vehicle recognition and analysis, it is mainly license plate recognition technology. License plate recognition technology is widely used in entrances and exits of parking lots, highway toll stations and other places. In recent years, it has developed rapidly: with the traffic electronic bayonet system, license plate recognition technology is widely used to capture vehicle traffic violations, which effectively reduces the number of vehicle traffic violations and greatly reduces the occurrence of traffic accidents.

3. Behavioral intelligence analysis. HD webcam this technology focuses on the analysis and processing of dynamic scenes. Typical functions include: Vehicle retrograde, defense zone intrusion detection, personnel focus detection, trip line crossing detection, rapid movement, personnel wandering detection and passenger flow statistics. Motion detection (VMD) is the “early intelligence” in this kind of intelligent analysis. VMD judges according to the motion changes of pixel blocks in the video picture. Due to the two-dimensional image intelligent analysis, the false alarm is high, so it is unable to identify whether the moving pixel block is interference or target. In addition, there are differences in algorithm technology between various security manufacturers, The accuracy of behavior and recognition intelligent analysis is generally not high.

High pixel

HD cameras with more than 3 million pixels were mainly launched by HD enterprises in 2012, and HD cameras with more than 2 million pixels were still rarely launched in 2012. With the introduction of CMOS technology, HD network cameras seem to have taken a shot in the arm. After 2013, cameras with 3 million, 4 million, 5 million, 6 million and 12 million pixels have sprung up like mushrooms. This is that technological innovation has brought innovation to the product system. In the existing mainstream security enterprises in the “Pearl River Delta”, “Yangtze River Delta” and “Bohai Rim”, almost high pixels have become the standard configuration of manufacturers, and even 4K has become the standard configuration of manufacturers. For users, 4K is not only the experience and enjoyment of vision, but the resolution of 4K is 4 times that of 1080p. If 4K camera and 1080p camera are used to shoot the same scene at the same field angle, 4K camera will use 4 times the amount of information used by 1080p camera to restore the scene, and the picture will naturally be clearer and closer to reality. From the perspective of “use”, since the amount of information of 4K picture is four times that of 1080p, more accurate intelligent analysis can be realized based on more information. Once 4K is deployed on a large scale, the accuracy of intelligent analysis can rise to a higher level, and richer and more amazing intelligent applications will be realized.

Starlight level

0.001lux and below are recognized as starlight cameras in the industry. The most representative starlight camera is ti dm8127 / anba S2 + Sony imx185 hardware scheme. At present, it is widely used in Ping’an City, finance, hotel buildings, Ping’an Village, port, highway and other projects without large-scale installation of supplementary lighting facilities, You can get a better demand for night HD color monitoring picture. The star level illumination monitoring technology is mainly affected by the lens, image sensor, back-end image processing technology and other factors. The manufacturers of safety enterprises also improve from the following aspects:

1. Use of large aperture lens: the lens is an important part of the camera component. Its role in low light monitoring application technology is to focus the light of the subject for the camera. The key of low light application and technology here is that the larger the aperture of the lens is, the greater the light input will be, that is, the increase of lens aperture can effectively improve the light input, So that the camera can obtain the ideal low illumination effect.

2. Select large target sensor: the essence of the camera is to convert light energy into electric energy, and the core component of quantification is the sensor. The function of the sensor is to photoelectrically convert the light of different intensities transmitted to it, convert it into voltage information, and finally generate digital image information. The part receiving light on the sensor is naturally the core of the core. If the camera has the same resolution, the larger the target area of the image sensor, the greater the light input per unit pixel, the stronger the ability to suppress noise, and the better the image quality when shooting at low illumination.

3. Good image processing technology: in the past, the camera used the traditional 2D algorithm to realize the noise reduction function, but now the 3D noise reduction technology is used. On the basis of the original intra noise reduction, through the comparison and screening of the images of the previous and subsequent frames, the noise position is found and its gain is controlled. The 3D digital noise reduction function can reduce the noise interference of the weak signal image. Because the appearance of image noise is random, the noise of each frame is different. 3D digital noise reduction automatically filters out non overlapping information (i.e. noise) by comparing several adjacent images. With 3D noise reduction camera, the image noise will be significantly reduced and the image will be clearer and more thorough, so as to display a relatively pure and delicate picture.

Responsible editor: CT

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