The definition index used to describe CCD sensor is the effective pixel in the horizontal direction of CCD sensor. At present, the effective pixels of two mainstream standard definition CCDs on the market are 5 10H and 760H respectively, which correspond to the definition of CIF and D 1 respectively. Although the horizontal definition of the camera can be improved from 540TVL to 560TVL through ISP optimization, it still can't reach the 650TVL required for analog HD due to the limited effective pixel number of CCD itself. Therefore, in order to realize analog HD, the CCD sensor must be 960 h.
Compared with 760H, the effective pixels of 960H have increased by 30%, which is reflected in the video image. Because the number of horizontal pixels has increased from 440,000 to 570,000, the image details have increased and the image is clearer.
Network service provider
The main functions of ISP are demosaicing (image interpolation), 3A, gamma correction, image denoising, wide dynamic and so on. To support analog HD, ISP must support 960H CCD, in order to achieve the horizontal definition above 650TVL.
In addition, in order to adapt to more applications, analog high-definition ISP has greatly improved the functions of image drying and wide dynamic. Analog HD ISP adopts 3D noise reduction technology, which adds the function of inter-frame noise reduction on the basis of the original intra-frame noise reduction, and the noise reduction effect is more obvious.
In the aspect of wide dynamic processing, the analog high-definition ISP also realized the inter-frame wide dynamic technology, which improved the wide dynamic range to 120dB (more than 6000 times), greatly exceeding the original 160 times wide dynamic effect.
camera lens
Camera lens is the most critical equipment in video surveillance system, and its quality (index) directly affects the overall index of the camera. In order to meet the definition requirements, the analog high-definition camera should choose a megapixel lens to achieve better results.
Application of analog high-definition camera
From the above technical analysis, we can sum up the characteristics of analog HD cameras as follows:
However, because it also outputs standard CVBS signals, it is completely compatible with the original analog standard definition system, transmission media, transmission distance, engineering construction and so on. No change, only by replacing the analog camera can the definition be improved. If equipped with Dahua's 960H DVR, not only the definition can be greatly improved by 30%, but also it has better wide dynamic and low noise effects;
For engineers, there is no need to change the construction method and additional training, which is in line with the original working habits;
Page 2: Application of Analog HD Camera
Analog signals are completely compatible, and it is easy to locate and eliminate faults. However, the network high-definition system needs to solve the problem of equipment compatibility, and when it fails, it needs to eliminate complex network problems first;
The analog high-definition camera continues the advantages of the simulator system, without coding and delay, and the image restoration effect is more realistic;
Cost-effective, Dahua launched a complete solution of analog high-definition camera +960H DVR. The code stream is controlled at about 2.5M, which is 25% higher than that of D 1. For the whole system, the cost of analog HD system is less than 20% higher than that of D 1 SD system with 30% higher definition. With the popularization of analog HD, the cost increase will be reduced to 1.
Based on the above characteristics of analog high-definition camera, the application of analog high-definition camera is illustrated by selecting bank business hall monitoring.
The business hall of a bank is an important place for the transfer of funds between banks and customers, which requires high security. Basically, analog video surveillance systems are installed. In view of the increasingly complex external environment and the ever-changing criminal means and forms, higher requirements are put forward for the existing video surveillance, so as to realize the high definition and intelligence of video surveillance and improve the security capability of video surveillance system. The monitoring of bank business hall is also a typical wide dynamic and low noise scene, so the requirements for cameras are higher.
The specific monitoring points are deployed as follows:
Outside the business hall: deploy 700-line analog high-definition infrared cameras to monitor the external environment of the business hall day and night;
Business hall: deploy 700-line analog high-definition wide dynamic camera or network high-definition camera to realize clear monitoring of people's faces in the hall and provide powerful image support for real-time monitoring and evidence collection afterwards;
Business counter: each window is equipped with 700-line analog high-definition wide dynamic camera to monitor the daily situation of tellers, standardize operations and provide service quality;
Internal office area: 700-line infrared hemispherical camera is deployed in each relatively closed office space to monitor the internal situation of the office, standardize the work and prevent the loss of internal property.
At present, the video monitoring system runs independently of other fire alarm systems, and it is impossible to realize the linkage video picture when the smoke or fire alarm occurs. A security vendor has also introduced a camera which can sense smoke and temperature, and realized the visual management of the fire risk system.
In this scheme, the camera with the national patent function of smoke temperature detection and the back-end 960H DVR are used to realize the superposition of temperature and smoke information and the alarm linkage of video preview storage, and the fire alarm system and video monitoring system are perfectly integrated to realize the visualization of the fire alarm system.