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The Technology You Must Know About HD PTZ Camera

Issuing time:2019-09-03 16:53Author:Zonda.cam@gmail.com

The Technology You Must Know About HD PTZ Camera

Video conferencing is increasingly used. As one of the core components of video conferencing, PTZ cameras play an important role in the effectiveness of video conferencing and conference quality. In the video conferencing system, the camera mainly implements functions such as image information collection, information digitization conversion, information transmission, and information restoration. Through independent research and development of image and audio information processing technology, transmission and conversion technology, we realize the overall coordination and function balance of camera hardware and information processing software, and provides high-quality video conferncing effects for customers while taking into consideration the cost.

Our R& D team has many years of experience and independent research & development and innovation capabilities. Our main technologies include: video image processing technolog (3A control algorithm), audio codec technolog, video codec technolog, autio iris technolog and so on.

1. Video image processing technology

The process of video image processing involves the process of collecting, transmitting, processing, displaying and playing back video image data. These processes together form an overall cycle of the system and can operate continuously. The most important in the scope of video image processing technology is the compression technology of images and the processing technology of video images. The company's video image processing technology mainly includes 3A basic core algorithm, Demosaic, CCM calibration, Noise Reduction and so on.

(1) 3A control algorithm

The 3A control algorithm is short for automatic exposure control (AE), automatic white balance control (AWB), and auto focus control (AF). 3A control is a necessary function of most camera equipment. The excellent 3A control algorithm has a very significant effect on the imaging quality of the camera equipment. It can achieve the maximum image contrast, improve the subject's overexposure or underexposure, and make the picture appear. The chromatic aberration under different light illumination is compensated, thereby presenting higher quality image information. The 3A digital imaging technology camera can effectively guarantee the high-quality output of the image and present a good adaptability to the environment. The 3A control algorithm is the core algorithm of video image processing. Each camera manufacturer has its own 3A control algorithm. The difference lies in the difference in imaging quality in the application.

  • AE

AE-Automatic Exposure affects image brightness. The specific influencing factors are the illumination of the scene, the aperture size of the camera, the exposure time and gain. In the case where the scene illumination is determined, the last three parameters can be adjusted to change the brightness of the image. The adjustment of these three parameters has the characteristics that the aperture adjustment is slow, the maximum exposure time is affected by the frame rate limit, and the gain value is increased to amplify the noise. How to achieve a balance between several influencing factors, improve exposure accuracy, and achieve the most realistic image presentation, which is the difficulty of automatic exposure technology. The traditional meaning of automatic exposure is that the IRE of the image output can reach the certain value and the exposure is accurate. Our automatic exposure algorithm adopts different exposures for the images of the over-light and the dark in the IRIDIX human-eye model. The weight makes the electronic imaging with limited tolerance as close as possible to the high latitude of the human eye, and the accuracy of the exposure is also greatly improved.

  • AWB

Automatic white balance (AWB) refers to the degree of fidelity of the picture color adjusted according to the light source conditions. Objects will have different degrees of chromatic aberration under different light illumination. Generally, the overall color difference signal of an image is used as color temperature data. When most areas of this image are covered by a uniform color, this color compensation may be lost. Part of the complete color. To compensate for this deficiency, some specific automatic white balance algorithms (AWB) have been proposed to accommodate different color temperature conditions. The traditional white balance adopts the gray world algorithm. The biggest problem is that white balance instability occurs in the case of large color block interference, and we optimize the gray world algorithm on the automatic white balance algorithm. When the RG/BG value of the actual conversion exceeds a certain threshold value, the judgment method of the large color block is performed, and the white balance is not calculated in the area, and the stability of the white balance can be greatly improved.

  • AF

The Autofocus Algorithm (AF) maximizes image contrast by moving the lens through the acquired image contrast. In general, autofocus technology achieves the highest image contrast by adjusting the position of the focus lens to achieve higher image contrast. Among them, obtaining the best focus point is an accumulating process, which compares the contrast of each frame image to obtain the largest contrast point in the lens movement range, and then determine the focusing distance. The basic algorithm is the hill-climbing algorithm, and the biggest problem of the hill-climbing algorithm is that it is prone to focus oscillating phenomenon. We improve the auto-focusing algorithm. On the basis of the traditional hill-climbing algorithm, the large-step fast judgment and the small step length precise positioning are added. The algorithm achieves the balance between the accuracy and the fastness of the autofocus effect.

(2) Demosaic

Demosaic is a software technology used to improve video quality, using a large number of VirtualDub filters and additional codec recompressed video processing to restore the mosaic. The image output by the image sensor commonly used in this technology is a sequence of RGRG...BGBG..., since the content acquired by a single image point has only monochrome data, and the actual required image is RGB three colors, so it needs to be restored. In the algorithm of demosaicing, the company has custom adjustment options for the adjustment of three color components, which can adjust the weight values in eight directions (up, down, left, right, top left, top right, bottom left, bottom right). In order to adapt to the characteristics of different sensors and lenses, to achieve maximum RGB color reproduction.

(3) CCM

Image sensors typically provide erroneous color reproduction, resulting in so-called cross-color effects due to signal crosstalk between pixels, resulting in images of erroneous colors (eg, bluish green). Color correction involves matrix multiplication of complex pixel data to achieve a pure color, and many situations in which image colors are accurately reproduced in the image system can be difficult, including spectral characteristics, illumination differences, and sensor characteristics. This technology is a systematic project, a single color change will affect the overall color accuracy, and has high requirements for the engineer's experience and depth of understanding of color. The company's color correction matrix technology supports offset compensation and can be used for color correction operations to adjust CCM to almost identical effect on different sensors and different lenses.

(4) Image Denoising

Image Denoising is a term used in image processing. In reality, digital images are often affected by imaging devices and external environmental noise during digitization and transmission, and are called noisy images or noisy images. The process of reducing noise in digital images is called image denoising, sometimes referred to as image denoising. In the video image, the noise is the detail of the picture, and the more noise will bring discomfort to the human vision. Software noise reduction processing will also use different algorithms. Some simple software will use fuzzy methods to reduce noise. This noise reduction effect is obvious, but the picture details are seriously lost. Professional software uses more advanced algorithms to reduce noise by adjusting the different color blocks of the noise (noise amplification is a color block) or advanced algorithms while maintaining the sharpness of the picture. Therefore, in the process of noise reduction, it is necessary to reduce noise while maintaining the sharpness of the picture. In many cases, adjustment is a balance between the two.

There are two main types of noise reduction processing technologies, one is 2D noise reduction processing based on single picture, and the other is 3D noise reduction processing based on continuous multiple pictures. The traditional 2D noise reduction processing technology has poor noise reduction effect in practical applications, and the application of 3D noise reduction processing technology will greatly extend the image output time. Based on the 3D noise reduction processing technology, the company simultaneously reduces the noise of the first few frames and the current frame image, thus achieving almost no delay 3D noise reduction processing, making the overall image output delay only need a single frame level.

2. Audio processing technology

In real-time audio processing technology, automatic gain control (AGC), automatic noise suppression (ANS), and automatic echo cancellation (AEC) are the three main technologies for audio processing, and are also major difficulties. The company has conducted in-depth research on these three technologies. The unique feature is that the three technologies are integrated into a single chip and integrated into the company's video codec device for simultaneous processing. This technology works with audio hardware circuitry to dramatically improve audio performance.

3. Video coding technology

At present, the industry mainly uses video coding standards such as H.264/MJPEG, and the ITU has officially approved the HEVC/H.265 standard as customers demand higher image quality and image size. This standard is called High Efficiency Video Coding. Compared with the H.264 standard commonly used in the industry, this standard has improved the transmission of higher quality network video under limited bandwidth, and only needs half the bandwidth of the H.264 standard to play the same quality video. The H.265 standard supports 1080p Full HD video, 4K (4096×2160) and 8K (8192×4320) Ultra HD video. It can be said that the H.265 standard allows network video to keep up with the "high resolution" of the display. As one of the professional manufacturers of HD camera products, the company has optimized the application of the H.265 standard. Under the transmission bandwidth of less than 1.5Mbps, it can realize 1080p full HD video transmission and improve codec efficiency.

4. Audio codec technology

In the high-definition camera audio codec technology, the company has carried out various audio coding and decoding standards such as G.711, G.716, G.721, G.722, SILK and other advanced audio codec standards such as AAC and G.726. Combined, and added AES-128 and AES-256 encryption standards. In particular, the AES-256 encryption grade product is currently a high standard encryption product on the market.

5. Auto-Iris technology

Auto-iris technology is an integral part of the auto-exposure algorithm. The company's treatment with the automatic aperture is not simple to achieve the maximum amount of light into the lens, but the dual requirements of the depth of field requirements and exposure accuracy of the actual use environment, in the bright enough environment, in the exposure accuracy Under the premise, reduce the aperture to achieve the maximum depth of field requirements; in the weak light environment, increase the aperture size as much as possible to ensure image quality, intelligently switch the working mode of the automatic aperture.

6. Other technologies

Our company also has advantages in product design, product structure design, noise control, motor control and so on. The company's high-definition camera has its own patent for appearance, independent design, independent research and development, and is unique in the industry. The compact structure design, low failure and high precision ensure the stability and reliability of the product when used in various environments. In terms of noise control technology, the low noise product design highlights its quiet, high-end features. The motor control technology has a unique S-type acceleration and deceleration effect. When the pan/tilt moves and stops, its acceleration and deceleration effect is smooth, and it has almost no frustration. It conforms to the human hand-controlled gimbal turning feel, which greatly improves the product experience and Comfort.

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Shenzhen AVLink Technology Co., Ltd


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