Technical analysis: How much do you know about wide dynamic cameras?
2020-04-20
WDR camera technology is a technology used to let the camera see the characteristics of the image under very strong contrast, when the high brightness area and the relatively low brightness area such as shadows and backlight under the illumination of a strong light source exist in the image at the same time, the bright area of the camera output will become white due to overexposure, and the dark area will become black due to underexposure, which seriously affects the image quality. The camera has limitations on the performance of the brightest area and the darker area in the same scene, which is usually the dynamic range, and the technical characteristics of the wide dynamic camera are to use the wide dynamic range to mainly solve the backlight compensation problem of the camera.
In terms of technical implementation, it is mainly divided into the following two types
1. CCD+DSP technology:
Dual-speed CCD with DSP processing mode, the core of this double exposure technology is for the scene with large contrast between light and dark, the camera first performs a rapid exposure to the bright area, obtains a clear and normal image of the bright area and stores it in the data buffer memory; 。 This avoids overexposure of highlights and underexposure of shadows, so that the entire frame is clearly visible to achieve wide dynamic range processing, but if different DSP chips are used, there are still obvious differences in specific details, such as sensitivity, color reproduction, white balance, etc.
2. CMOS+DPS technology:
DPS adopts each pixel individual exposure and control technology, coupled with the linear superposition of multi-frame images collected by CMOS sensor to synthesize a complete image, compared with the two exposure imaging of CCD, there is a higher dynamic range, numerically speaking, the CMOS camera using DPS technology can reach 120dB on the current processing technology, while expanding the dynamic range, DPS also solves the shortcomings of CCD sensor in processing dynamic range and color authenticity, and its color reproduction is more realistic, which can meet the requirements of the applicationThe camera using this technology uses an analog-to-digital converter in each pixel of the digital image sensor, which directly converts the optical signal into a digital signal when it is captured, minimizing the attenuation and interference of the signal in the arrangement.
At present, most of the general surveillance network cameras use CMOS+DPS wide dynamic technology, and the application scenarios are wide. Including finance, education, transportation and other fields, wide dynamic camera has become an indispensable function of high-definition cameras, and the market demand is very strong.
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