In order to better "understand" the specification parameters, we need to understand the "mystery" under the parameter indicators that have a great impact on product performance. Taking a surveillance camera as an example, we briefly analyze the two key indicators of high clarity and minimum illumination.
Sharpness indicator. This is the first parameter to look at when looking at the camera's color page. In a sense, the camera's sharpness index determines its grade. Most analog products on the market now have a sharpness level of 500 lines or more, and some 960H solutions have reached 700 lines. Digital cameras, on the other hand, represent the level of sharpness they can achieve at the pixel level, such as 1.3 million pixels and 2 million pixels, which roughly correspond to 700TVL and 1000TVL, respectively. However, individual businesses may also have false or partial conditions. If there is an analog camera monogram horizontal resolution of 540TVL, a little attention will be found behind the small print "central resolution". what does this mean? Limited by the camera's own lens, CCD + DSP program and other factors, some cameras can only show the highest sharpness near the center of the image, while the edge can not achieve this clarity, the overall average resolution may be only 520TVL, Even lower. So you need to pay extra attention to your choice.
The minimum illumination index. This is an important parameter of the analog camera, but this parameter can be said to be the most intriguing camera indicator (no one). The camera's minimum illumination is also called the camera's sensitivity. There are many factors that affect the camera's minimum illuminance value, which mainly include the light quantity parameter (F-number) of the camera lens, the light source color temperature parameter, the video level amplitude IRE level, and the camera's several function parameter settings. First, it is the light quantity parameter. A lens with a f-stop of F1.4 has twice the throughput of the F1.2 lens, while the F1.0 lens has 100 times the light throughput of the F10 lens. Therefore, using lenses with different F values ​​will have a decisive influence on the determination of the camera's minimum illuminance value. Second, the light source color temperature. Color temperature is an indicator of the wavelength of light in a light source. A 3200K light source has most wavelengths between 600 nm and 900 nm. A 9300K light source has wavelengths between 300 and 500 nm. Therefore, different color temperatures will completely change. Test Results. On a typical CCD sensor, a light source with a wavelength of 600 nanometers will produce 10 times more electrons than a light source with a wavelength of 900 nanometers. This is why the color temperature is particularly marked as the meaning of the minimum illuminance measurement result. The third is the IRE level. The maximum amplitude of the CCD camera's video output is typically set at 100 IRE (or 700 mV). A 100 IRE video representation can completely drive a monitor with the best brightness and contrast.
The 50 IRE video represents only half the contrast, 30 IRE (or 210 mV) represents only 30% of the original amplitude, and typically 30 IRE is the lowest value of the available image. Therefore, there is no actual comparability of the minimum illuminance measurement results without the IRE rating. Finally, it is the camera's special function settings. Some cameras have a frame accumulation (also known as sensitivity boost) function. This function allows the CCD to accumulate more electrons per frame of the image in a way that reduces the scanning speed so as to present a highlight image in a low illumination environment. Turning on this function can increase the minimum illuminance measurement by a geometric multiple. For example, a camera with a 512x increase in sensitivity can easily achieve a level of 0.0001 Lux, but at the expense of image coherence, the imagery is full of animation. To sum up, a meaningful minimum illuminance indicator should be annotated with its F value, color temperature, IRE level, and whether the frame accumulation setting is turned on, such as 0.5 Lux (F1.45600K30IRE, sensitivity is raised OFF).
Food Additives Refers to the production of food by the food manufacturer in the process of adding some chemicals, used to change the color of food, smell, or adjust the food taste and prolong the preservation time (preservatives, antioxidants), but some will Leading to cancer, such as many of the meat material added by some of the substances in the stomach due to protein, stomach acid, additives generated by the interaction of nitrite, can lead to physiological and chronic lesions. These chemicals are known as food additives.
main effect
Food additives have greatly contributed to the development of the food industry, and known as the soul of the modern food industry, which is mainly to the food industry to bring many benefits, its main role is as follows:
1. Preserving to prevent deterioration such as: preservatives can prevent food spoilage caused by microorganisms, extend the shelf life of food, but also have to prevent the pollution caused by microbial poisoning. Another example: antioxidants can prevent or delay the oxidation of food deterioration, to provide food stability and resistance to storage, but also to prevent the possible harmful oil automatic oxidation of the formation. In addition, can also be used to prevent food, especially fruits, vegetables, enzymatic browning and non-enzymatic browning. These are the preservation of food is of a certain significance.
2. Improving the sensory properties of food The color, smell, taste, shape and texture of food are important indicators of food quality. Appropriate use of colorants, colorants, bleach, edible spices and emulsifiers, thickeners and other food additives, can significantly improve the sensory quality of food to meet people's different needs.
3. Maintain or improve the nutritional value of food in food processing properly add some of the natural nutritional range of food nutrition enhancer, can greatly improve the nutritional value of food, which prevent malnutrition and nutritional deficiencies, promote nutritional balance, improve People's health level is of great significance.
4. Increased variety and convenience of food The market now has as many as 20,000 kinds of food for consumers to choose, although most of these food production through a certain packaging and different processing methods, but in the production process, some color , Fragrant, taste with the whole product, mostly to varying degrees to add the coloring, aroma, seasoning and even other food additives. It is these a lot of food, especially the convenience of food supply, to people's lives and work to bring great convenience.
Now commonly used food pigments include two categories: natural pigments and synthetic pigments. Natural pigments come from natural, mainly extracted from plant tissue, and also include some pigments from animals and microbes. Synthetic pigment refers to the use of artificial chemical synthesis of organic pigment, mainly in coal tar separated from the aniline dye made of raw materials. In the course of a long period of Food Additive reporting process, because people do not recognize the harm of synthetic pigments, and synthetic pigments and natural pigments compared with bright color, strong coloring, stable nature and cheap, many countries in the The food processing industry generally uses synthetic pigments. With the development of society and the improvement of people's living standards, more and more people in the use of synthetic food in the food will not cause harm to human health questioned. At the same time, a large number of research reports that almost all of the synthetic pigment can not provide nutrients to the human body, some synthetic pigment and even endanger human health. Eat a fine snack, fast food lunch, fragrant hot dog, glance at the printing of exquisite packaging food on the nutritional table, you will find that each food has additive ingredients. It is understood that the conversion of fat, refined cereal products, salt, high fructose syrup four components in the processing of food is the most common, these ingredients harm the human health. Some if there are too much harm, such as: citric acid, aspartame, sodium Finland white pigment, vanillin, potassium ... basically no harm, as long as it is added But not excessive
Additives
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