Infrared camera refers to the visible light visible to the human eye. The order of wavelengths from long to short is red, orange, yellow, green, blue, purple, and shorter. The light with a wavelength shorter than the wavelength of violet light is called infrared. The light with a longer wavelength than red is called infrared. The infrared is not visible to the naked eye. Because the digital camera uses the CCD to sense all the light, it causes the shot image to be very different from the image that we see with only the visible light. In order to solve this problem, the digital camera is equipped with an infrared filter between the lens and the CCD, its role is to block the infrared light from entering the CCD, so that the CCD can only sense the visible light, so that the video captured by the digital camera and our naked eye The images seen are consistent. At present, most infrared cameras use LED infrared light emitting diodes as the main material of infrared cameras.
With the development of CCD and DSP technology, low-light infrared cameras have become mature and stable. Many manufacturers (businessmen) have lower the standard of the camera's illumination parameters, from 1.0lux to 0.1lux, to 0.001lux, etc. Does the camera really have such high sensitivity? In order to truly understand the low-intensity infrared camera, elaborated from the following aspects.
Lens
As an important part of the infrared camera part, its role is to focus the light of the subject for the CCD of the infrared camera, so that the scene is imaged on the CCD. The amount of light that can be captured directly determines the clarity of the CCD image. To measure how much light is taken by the lens, it is called the amount of light, and the amount of light entering the lens is expressed by the F value (aperture). F value = f (focal distance) / D (effective aperture of the lens), which is inversely proportional to the aperture, and is proportional to the distance from the focal point. With the same focal length, the larger the aperture of the lens, the smaller the F value and the greater the amount of light entering the lens. The F value of common lenses is mostly 1.2, 1.4, and there are currently F1.0 lenses. Therefore, in order to make the infrared camera obtain the ideal low illumination effect, it is necessary to configure a lens with a suitable or configured F value.
CCD photosensitive device
At present, there are three major suppliers of CCDs for infrared cameras, namely SONY, SHARP, and LG. In these three types of CCDs, SONY's CCD sensitivity is relatively good. The commonly used SONY CCD low-light technology is SuperHADCCD; later SONY has developed super- Sensitivity CCD, SONY called REVIEWCCD, the sensitivity of the CCD is 5 times SuperHADCCD.
In addition, the size of the CCD also has a great impact on the sensitivity, the larger the size, the better the sensitivity. In order to make infrared cameras have a lower illuminance index, 1/2-inch CCD cameras are often used. Data shows that the 1/3-inch CCD has only 56% of the 1/2-inch CCD, while the 1/4-inch CCD has only 44% of the 1/3-inch CCD.
Image DSP processing
Since the development of low-intensity infrared cameras, not only has the development of hardware technology, but also outstanding performance for DSP image processing, such as color to black technology and low-speed electronic shutter, that is, the emergence of frame accumulation technology.
Color to black technology
The sensitivity of a black-and-white camera is usually much higher than that of a color camera. Since the black-and-white camera, the DSP operation only processes two colors, namely black and white, so a considerable part of the low-intensity infrared camera now has a color to black and white. The function, that is, the daytime color image, is converted into a black and white image by software processing at night, and a lower illumination is obtained by sacrificing the color effect.
The process of converting color to black and white is controlled by the charge converted by the CCD to collect light. When the charge intensity reaches a certain critical value, it is automatically converted to a black and white image. Similarly, to ensure that the critical value does not cause repeated switching, it will do A delay in processing.
With the development of CCD and DSP technology, low-light infrared cameras have become mature and stable. Many manufacturers (businessmen) have lower the standard of the camera's illumination parameters, from 1.0lux to 0.1lux, to 0.001lux, etc. Does the camera really have such high sensitivity? In order to truly understand the low-intensity infrared camera, elaborated from the following aspects.
Lens
As an important part of the infrared camera part, its role is to focus the light of the subject for the CCD of the infrared camera, so that the scene is imaged on the CCD. The amount of light that can be captured directly determines the clarity of the CCD image. To measure how much light is taken by the lens, it is called the amount of light, and the amount of light entering the lens is expressed by the F value (aperture). F value = f (focal distance) / D (effective aperture of the lens), which is inversely proportional to the aperture, and is proportional to the distance from the focal point. With the same focal length, the larger the aperture of the lens, the smaller the F value and the greater the amount of light entering the lens. The F value of common lenses is mostly 1.2, 1.4, and there are currently F1.0 lenses. Therefore, in order to make the infrared camera obtain the ideal low illumination effect, it is necessary to configure a lens with a suitable or configured F value.
CCD photosensitive device
At present, there are three major suppliers of CCDs for infrared cameras, namely SONY, SHARP, and LG. In these three types of CCDs, SONY's CCD sensitivity is relatively good. The commonly used SONY CCD low-light technology is SuperHADCCD; later SONY has developed super- Sensitivity CCD, SONY called REVIEWCCD, the sensitivity of the CCD is 5 times SuperHADCCD.
In addition, the size of the CCD also has a great impact on the sensitivity, the larger the size, the better the sensitivity. In order to make infrared cameras have a lower illuminance index, 1/2-inch CCD cameras are often used. Data shows that the 1/3-inch CCD has only 56% of the 1/2-inch CCD, while the 1/4-inch CCD has only 44% of the 1/3-inch CCD.
Image DSP processing
Since the development of low-intensity infrared cameras, not only has the development of hardware technology, but also outstanding performance for DSP image processing, such as color to black technology and low-speed electronic shutter, that is, the emergence of frame accumulation technology.
Color to black technology
The sensitivity of a black-and-white camera is usually much higher than that of a color camera. Since the black-and-white camera, the DSP operation only processes two colors, namely black and white, so a considerable part of the low-intensity infrared camera now has a color to black and white. The function, that is, the daytime color image, is converted into a black and white image by software processing at night, and a lower illumination is obtained by sacrificing the color effect.
The process of converting color to black and white is controlled by the charge converted by the CCD to collect light. When the charge intensity reaches a certain critical value, it is automatically converted to a black and white image. Similarly, to ensure that the critical value does not cause repeated switching, it will do A delay in processing.
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