Tags: CCD sensor clarity
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Security video surveillance development for more than 20 years, along with the "Moore's Law" type iterative change of CCD technology and DSP technology, video clarity has evolved from the original analog 300 line to the latest HD 1000 line, especially since 2010, HD products Endlessly, it can be divided into three types: 960H analog HD, HD-SDI digital HD and 720p/1080p network HD. Just as the major cuisines meet different tastes, diversified HD meets different user needs. The high-line analog camera, with its distinctive features, will surely occupy the mainstream market in the next few years.
High-line analog camera features
The clarity of the camera is generally represented by the TV line TVL, such as 480TVL, 540TVL, etc. The industry's definition of 650TVL or above is called analog high definition. Generally speaking, there are three main aspects to determine the resolution of the camera, namely CCD sensor, ISP image signal processing unit and lens. This paper will discuss the technical characteristics and application of high-line analog camera from these three aspects.
1, CCD sensor
The sharpness index used to describe the CCD sensor is the effective pixel in the horizontal direction of the CCD sensor. The effective pixels of the two standard definition CCDs currently on the market are 510H and 760H, respectively, corresponding to the definition of CIF and D1. Although the horizontal resolution of the camera can be increased from 540 TVL to 560 TVL through ISP optimization, it is still limited to the number of effective pixels of the CCD itself, and still does not reach the 650 TVL required for analog HD. Therefore, to achieve analog HD, the CCD sensor must be used. 960H.
At present, the analog HD on the market adopts the EXVIEW HAD CCD released by SONY at the 2010 AMB. The horizontal effective pixels reach 976H, which is 30% higher than the 760H and 960H on the effective pixels, and the low-light sensitivity is also improved. Doubled. Reflected on the video image, because the horizontal pixel points increased by 570,000 from 440,000, the image details increased, the image was clearer, the image noise was smaller under low illumination, and the picture was clearer. From Figure 1, we can visually compare the effects of three specifications of CCD on the picture.
Figure 1 Variation of 960H relative to 760H pixel
For a more detailed description of the three specifications of the CCD, refer to the following table:
960H CCD sensor 760H CCD sensor 510H CCD sensor
Effective pixels PAL976 (H) × 582 (V) Approx. 570K Pixels 752 (H) × 582 (V) Approx. 440K Pixels 500 (H) × 582 (V) Approx. 290K Pixels
NTSC976 (H) × 494 (V) Approx. 480K Pixels 768 (H) × 494 (V) Approx. 380K Pixels 510 (H) × 492 (V) Approx. 250K Pixels.
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