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Analysis Of The Clarity Of The Surveillance Cameras And The Most Low-Light Indicators

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#1 iacemomo


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Posted 28 February 2013 - 01:32 AM

Analysis of the clarity of the surveillance cameras and the most low-light indicators
    How to recognize a security product? Believe that in most cases the user is to understand through its parameter indicators. Users rarely have the opportunity or can put in the time and labor costs to treat selected products 11 pager test. Therefore, the understanding of a product, or start from the specifications. Still camera, for example, examine the parameters include: the basic parameters of the CCD size, horizontal resolution, minimum illumination value, the signal-to-noise ratio, and shutter speed, automatic white balance, automatic gain power supply, installation, communications interface hardware supporting conditions. Integrated camera lens performance indicators needs to be investigated. The list of these parameters are indicators enough to make the users get confused, how "Quweicunzhen, you must first clear demand for product selection and corresponding demand to examine key indicators.
    In order to better understand "Specifications, we need to understand the" mystery "in the larger parameters of impact on product performance. Surveillance cameras as an example, we have a brief analysis of the clarity, minimum illumination attention focused indicators.
    Definition of indicators. This product color pages to see the camera at first glance parameters of concern. Sense the camera's resolution the indicator determines its grade. Now available in the market most of analog products with a level of more than 500 lines of clarity, the products of section 960H program has reached 700 lines of horizontal. Digital video cameras, multi-pixel level performance can reach a level of clarity, such as 1.3 million pixels, 200 million pixels, to roughly correspond 700TVL and 1000TVL. However, individual businesses will present a virtual standard or sweeping. If analog camera Monogram level of resolution 540TVL, pay attention will find behind the words, "center sharpness. What do you mean? Limited by the camera comes with lens, CCD + DSP programs and other factors, some cameras can only be close to the center of the image position showing the highest resolution in the edge of the part you can not achieve this clarity, the overall average to distinguish rate may only 520TVL, or even lower. Need extra pay attention to the choice.
    Minimum illumination indicators. This is an important parameter for analog cameras, but the parameters can be said to be the most tricky camera indicators (no one). Minimum illumination of the camera, also known as the sensitivity of the camera. Affect camera minimum illumination value of many factors, including the amount of light through the lens of the camera with parameters (F value), set the parameters of the color temperature of the light source, video the level amplitude IRE level, and the camera function parameters.
    First, the amount of light through parameters. An aperture of F1.4 lens through the level of the amount of light is F1.2 lens is twice as compared to F10 lens F1.0 lens 100 times the amount of light. Therefore, the use of different F value of the lens, have a decisive influence on the determination of the camera minimum illumination value.
    Secondly, there is a light source color temperature. The color temperature is expressed indicators of the light source in the wavelength of light the contents of a 3200K light source of most of the wavelengths are between 600 nanometers and 900 nanometers, and a 9300K light source of most of the wavelengths are between 300 to 500 nanometers, so different color temperature will completely change test results. In a typical CCD sensor, a light source of a wavelength of 600 nm than the wavelength of a 900 nm wavelength of the light source produce 10 times more electronic. This is why the color temperature is particularly marked significance to the minimum illumination measurement results.
    Third, in IRE level. The maximum amplitude of the video output of the CCD camera is generally set in 100IRE (or 700 mV), a 100IRE video can completely drive a monitor the performance of high-quality images of the best brightness and contrast. 50IRE video represents only half of the contrast, 30IRE (or 210 mV) represents only 30% of the original amplitude, usually 30IRE minimum performance can be used the values ​​of the image. Therefore, the a minimum illumination measurement results that did not mark the IRE level not with the actual comparable.
    Finally, the special features of the camera settings. Some cameras have a frame accumulation (also known as the sensitivity enhancement) function, this function is to reduce the scanning speed for the CCD accumulation of electrons in the intake of each frame, this exhibit highlighting screen in low-light environments. Turn this feature allows the minimum illumination measured value exponentially enhance. If the camera in a 512-fold sensitivity enhancement can easily reach 0.0001Lux Star-class, but at the expense of the full sense of the continuity of the image, the image rendered animation. In summary, the the minimum illumination indicators should have significance Note F value, color temperature, IRE level, and whether cumulative set to open the frame, 0.5Lux (F1.45600K30IRE the SensUp OFF).

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