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As an important member of HD products, HD cameras often do not know where to judge its performance when choosing. I believe that the performance of HD camera is mainly considered from the following aspects:
First of all, when users choose HD cameras, they need to understand their own needs. HD cameras are mainly used for monitoring financial systems and road traffic. Because these places have special requirements for images, if the user uses the location, it is not necessary to see the face. Features, license plate numbers, etc., there is no need to choose HD cameras, it is ok to choose an ordinary camera. After all, HD cameras are higher in price than ordinary ones, so we must first define our own needs when choosing.
The second is the function of the camera, which is mainly reflected in the clarity of the picture. When viewing the picture, the main observation is static definition, dynamic definition, color reproduction, and shooting scenery, scenery, flowers, moving objects. When you look at the picture, it is clean and the color is natural and realistic. The clarity of the picture is not only the horizontal resolution, but also the wide dynamics, automatic white balance, sharpness adjustment of the image, super digital noise reduction, intelligent digital automatic metering compensation and so on. When detecting the wide dynamic function, it is necessary to observe whether the transition between the bright area and the dark area is clear and natural, and whether the wide dynamic range can be automatically adjusted. A good camera will have rich layers and delicate performance in both the bright and dark areas. When looking at the license plate under the headlights at night, the outlines, filaments and license plates of the headlights are very clear and there are no vertical lines. The low illumination is to observe whether the camera's monitoring picture is clear at night, and how the noise is. These aspects all affect the function of the camera.
The third is the other aspects of the camera, such as the camera's operation settings. The current HD camera settings are mainly adjusted by menu and dialing. The camera with menu needs to pay attention to whether the menu function is rich, whether Easy to adjust, can meet different complex monitoring environments. In addition, some cameras have different modes, and users only need to select according to different environments when they use them. Also depends on whether the data interface of the camera is rich, because during the use, there will be a phenomenon that the surveillance camera cannot work normally due to environmental or human damage. At the time of installation and debugging, you should also pay attention to the lens selection, because the quality of the lens is not good, or the selection is not good, which will affect the clarity of the picture to a large extent. Also pay attention to the camera's accessory products, because in order to achieve high-definition effects, in addition to the front-end is a high-definition camera, the transmission system, the intermediate system and the terminal display system must meet the bandwidth and compression requirements. Finally, look at the technical support of the camera manufacturers, including whether it can provide specialized technical training, detailed explanation of the special functions and operation menus of the products, and whether maintenance can be carried out in the shortest time after problems occur.
HD camera composition
The focus here is on HD-SDI or IP HD cameras:
1. A camera CCD or CMOS imaging device converts an optical image into an electrical signal and outputs an electronic image signal.
2, AFE, analog front end, used for CCD imaging, digitize the CCD image signal, and generate CCD control timing. For the CMOS type imaging device, the digital signal can be directly output, so the AFE analog front end is not required.
3. The CPU is the core device of the entire HD camera. It mainly performs image signal processing (ImageSignalProcessor) and image signal encoding and decoding (codec is MPEG4, H.264 standard image data, etc.). The early CPU, DSP (DigitalSignalProcessor), mainly performs image signal processing, such as lens correction, gamma correction, edge correction, auto exposure, auto focus, automatic black and white balance, anti-shake and other processing and control.
The CPU of the IP high-definition camera also needs to complete the encoding and compression of the image, and then output through the IP network port, and the HD-SDI high-definition camera outputs the original digital signal through the HDMI or HD-SDI port without encoding compression. In general, in addition to the image processing and encoding functions, the CPU also completes the HD camera system control and calculation, and serves as the central processor of the entire system.
4. Storage interface: Storage mainly refers to data storage such as memory card/hard disk.
5, signal output interface: HDMI for high-definition digital multimedia interface, support high-speed signal transmission rate of 5Gpbs or more, for civilian consumer electronic interface; HD-SDI for high-speed serial interface, in line with the SMPTE organization for digital video and video for film and television studio Signal transmission is a professional standard. Its early support for standard-definition digital TV signal 270 Mbps rate has been developed to transmit 1.485 Gbps high-definition digital TV signals, and then to the current 2.97 Gbps high-speed signals for the transmission of RGB 24 bit high-definition digital TV signals.
HD camera technology development
With the gradual popularization of high-definition video system applications such as high-definition professional video cameras, high-definition video conferencing, and high-definition video surveillance, the HD video era has come. For the majority of video industry practitioners, important changes in camera technology are worthy of attention.
1, HD camera is a digital camera
CMOS high-definition cameras start with CMOS Sensors output image signals. The image signals in the entire system are digital signals, and digital signal processing technology runs through the system. This is fundamentally different from standard-definition cameras. Standard-definition cameras, many models of image chips output analog image signals, and the whole machine also outputs many analog image signals.
CCD high-definition camera Although the image signal output by the CCD chip is an analog signal, it is converted into a digital signal after AFE (analog front end), and the subsequent part of the system is also digital signal processing technology to complete image signal processing and output.
2. A series of technological innovations brought by digital cameras
i. HD cameras often perform image compression, such as MPEG4 and H.264 compression, in the DSP image signal processing stage. This is a feature brought about by digital image signal processing. In the era of standard definition cameras, video servers with video and video compression encodings are often separated.
Ii. The high-definition video data of the HD camera is large and high speed. The high-speed high-definition video data of digitalization has led to significant changes in the high-definition era of transmission media and transmission equipment in the SD era, and it is no longer applicable. Uncompressed 1080P HD data can reach more than 1Gbps. After H.264 algorithm image compression, the data traffic will also reach 8Mbps or even higher. For video surveillance applications, this change can even be said to be huge. High-speed digital signals, to a large extent, can not use standard-definition analog image signal transmission equipment and networking.
Iii. In the era of standard definition, when digital video processing such as video server and IPCAM is digitally processed, in many cases, the subjective and objective quality of the image signal is sacrificed, and the convenience of digital transmission and storage is exchanged. In the HD era, HD cameras are digital cameras, and this is no longer the case.
Discuss HD camera performance and composition
[ Huaqiang Security Network News ] With the rapid development of high-definition surveillance, HD cameras have been widely used. A high-definition camera can achieve the monitoring effect of several ordinary cameras, which is highly recognized by customers. Let's discuss the performance and composition of HD cameras. HD camera performance judgment