ความรู้เบื้องต้น CCTV: กล้องรับภาพ (CAMERA)

ความรู้เบื้องต้น CCTV

กล้องรับภาพ (CAMERA)

โดยทั่วไปแล้วจะถูกแบ่งง่ายๆ ออกเป็นสองชนิดคือ กล้องสี และกล้องขาวดำซึ่งขึ้นอยู่กับ ความต้องการ ของผู้ใช้และสถานที่ในการ ติดตั้งซึ่งต้องประกอบไปด้วย ลักษณะ ของการใช้งานจริง ยกตัวอย่างเช่น

กล้องสี ควรใช้งานกับสถานที่ที่มีแสงสม่ำเสมอ เช่น ซูปเปอร์มาเก็ต, มินิมาร์ท, ร้านทอง ฯลฯ เป็นต้น จากกลุ่มที่ยกตัวอย่างให้เห็นนั้นมีความ เหมาะสมกล่าวคือกล้องสีสามารถแยกแยะรายละเอียดหรือสีของสิ่งของ ได้ดี และในสถานที่ที่ยกตัวอย่างดังกล่าวก็มีการใช้แสงสว่างค่อนข้างมาก และสม่ำเสมอภาพที่มา ปรากฎบนหน้าจอมอนิเตอร์ ก็จะมีความชัดเจน

กล้องขาวดำ กล้องชนิดนี้เป็นกล้องที่ใช้แสงในการรับภาพต่ำมาก (LUX) เหมาะอย่างยิ่งที่จะใช้งานในด้านการรักษาความปลอดภัยเนื่องจาก สามารถดูในเวลากลางคืนได้ ดีกว่ากล้องสีเหมาะสำหรับโรงงานอุตสาหกรรม เช่น ในอาคาร, คลังสินค้า, โรงงาน, กระบวนการผลิต, พื้นที่อันตราย, เคาเตอร์เก็บเงิน, ลานจอดรถ, ปั๊มน้ำมัน หรือสถานที่ที่ใช้อุปกรณ์ดูแลรักษาความปลอดภัย

หมายเหตุ ปัจจุบันกล้องโทรทัศน์วงจรปิดจะใช้แผงรับภาพแบบ CCD (CHARGE COUPLE DEVICE) ซึ่งเป็นอุปกรณ์เซมิคอนดัคเตอร์ประเภทหนึ่ง ในกล้องราคาถูกจะไม่มีหน่วยประมวลผลภาพ และหน่วยความจำ ซึ่งเรียกว่าส่วนประมวลผลภาพดิจิตอล (DSP : Didital Image Signal Processing) ซึ่งจะทำให้กล้องที่ไม่มีหน่วยประมวลผล DSP อยู่จะซีดจาง และความคมชัดลดลง เมื่อใช้งาน ผ่านไปช่วงหนึ่ง

 

New Methods Enhance Sunell's Manufacturing Efficiency

A product's success relies on stable quality, and manufacturing is the key to providing stable quality. In a previous article in A&S China Best Buys, we presented a general picture of how Sunell plans to refine its manufacturing procedure. In this issue, A&S China Best Buys unveils how far the company has come to achieve its goal.
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A happy working environment is essential to a manufacturing base and to acknowledge its understanding of this belief, every employee at Sunell has a smiley faced pin on his or her uniform. Gary Du, Vice Director of Manufacturing Center at Sunell, organized this event. Through the event, Du emphasized how a happy working environment can increase staff's efficiency. “There are plenty of measures to increase people's efficiency,” said Du. “This is merely for the people's mentality. Right now, I am conducting many other reformations.”
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Since the closure of 2007, Sunell adopted several approaches to reform its manufacturing management, such as 5S, production lines reform and 3T management. Taking 3T for example — Total Quality Management, Total Productive Maintenance and Toyota Production System — the company has well established the first phase and is now moving toward the second. Du pointed out that it still requires two years to fully complete the 3T management. “Afterwards, we have plans to relocate the company's resources for other purposes,” Du said.
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However, change comes with resistance. Though the company has adopted these new management approaches, they were difficult to implement at the beginning, especially in manufacturing center. “The most crucial is talent and training makes people to be a talent. Training is perhaps the most important challenge to overcome,“ said Du. “In order to meet different markets' requirements, our staffs, hence, have to be capable of working independently. Therefore, we will establish skill improvement workshop (SIW) to keep our staffs staying ahead.“
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"At the beginning, rather than lecturing them about the method's theories, I showed our employees how these new methods can help them become more efficient workers,” Du explained. “This is the only way to make them believe that you are helping.” At the manufacturing front, the company started to abandon the traditional production line in order to facilitate the production procedure. “The Cell- and Uline production have been customized for Sunell,” said Du. “The company offers a wide range of surveillance products. Therefore, we need to enhance our manufacturing capacity and efficiency.”
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The new production line has proved its success, with higher efficiency and more product capacity. Du compared previous statistics with current ones, after production reformation was adopted. The results showed that overall efficiency increased from 45 percent to 80 percent.
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Quality Assurance


Du plans to bring Sunell to another stage. Most video surveillance manufacturers in China still use physical testing via staff's eyesight in regards to image resolution, S/N ratio and distortion. With only a basic resolution chart and testers' experience however, a product's quality cannot be guaranteed one hundred percent. Du plans to introduce software based testing for products.
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"I have purchased a capture card from an US-based company,” Du said. “After capturing the image, the software analyzes the image, turns i t into f igures and processes it with specific software to examine resolution, S/N ratio and so on more precisely. This solution has a long way to go but I would say that it yields much opportunity in China.”
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Moreover, Sunell has a strict quality control procedure. There are several tests involved in the various stages of the production line. From the initial PCB boards, to the finished products, to packaging, Sunell conducts process quality control (IPQC), housing testing, aging testing, out quality control (OQC) and open box audit (OBA). With these quality control measures, Du is proud to say that Sunell's product performance can meet or even exceed customers' requirements.
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In today's recession period, buyers are becoming ever more critical about quality. Sunell's new method of manufacturing and management has only one goal — to provide the market stable and quality products.

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Fine-Tuning Traffic

To run safe and efficient cities on a daily basis, traffic control systems and operators must be in tune with public surveillance systems and first responders to gather and share information.
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We see city surveillance projects in Asia revolving around traffic monitoring and road safety. In China especially, video surveillance solutions for safety and requirements are accommodating for growing traffic,” said Peter McKee, Global Marketing Director of Mobotix. While Asia might be a chief purveyor of traffic monitoring, cities elsewhere in the world in the United States, Latin America and Europe are seeing public surveillance tied to traffic monitoring systems. Keeping track of highways and junctions, import and export of goods and daily movement of people going to and from work or leisure are all part of helping society run smoothly, said Lars Thinggaard, CEO of Milestone Systems, and IP video surveillance is the monitoring tool that helps do the job better.
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With 360 degree view cameras and intelligent analytics like license plate recognition, tracking, identifying traffic density and motion detection, the capabilities of traffic monitoring stretch far and wide. Integrated with city surveillance, first responders can strengthen their practice, catching perpetrators and tracking their vehicle's movements.
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Junction Monitoring
Multigated junctions, with several entry and exit points see accidents, collisions, fights and eventually law suits as frequent occurrences. It is therefore essential for junctions to be properly monitored.
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Small and light megapixel cameras can be mounted on a pole, wall or harness to give operators a 360 degree view to monitor cars; with license plate recognition, cameras effectively record plates and the system can even recognize, through quick database searches, if cars in the junction have unpaid tickets, said McKee. License plate recognition systems integrated with public surveillance systems are more likely to catch a stolen car via recognition of its license plate.
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Using event management metadata, cameras positioned high above large junctions can track and classify types of vehicle (bus, bicycle, van, car), and monitor their average speed and direction of travel. This information can be used to do a number of useful things; traffic monitoring authorities can model the data to redesign a better junction, or alter traffic signals to reduce flow, said Michael Wilks, CEO of Scyron.
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Highway Surveillance
For safer traffic management on highways, behavioral analytics can notify traffic managers when traffic is heaviest. “You want to maximize the effectiveness of high occupancy vehicle lanes so you can make sure these and any extra lanes are open to traffic at times they're most needed,” said Ed Troha, MD of Global Marketing, ObjectVideo.
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Traffic surveillance extended to highways also pushes people to abide by speed limits; “people act differently when they think they are being monitored and it is often impractical and sometimes dangerous to put officers on site for these types of traffic violations,” Lee Caswell, Cofounder and CMO of Pivot3.

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H.264 Facts and Fiction

It seems everyone in the security industry is talking about the use of the H.264 compression standard for digital video, which produces high-quality video using less bandwidth than the commonly used JPEG compression. But how does H.264 differ from JPEG, and are the proposed benefits of H.264 compression too good to be true? Are there any hidden costs to using H.264 in security applications? Let us focus on the basics of the H.264 compression technology to separate facts from fiction and dispel a few myths and misconceptions.


H.264 and JPEG: How They Are Alike
H.264 and JPEG are two closely related standards: computationally they belong to the same family of compression methods. Both use similar or identical techniques to compress the video, such as transforming the video signal into frequency domain, applying quantization to the frequency-transformed signal, using variable length coding, and many other similar or identical techniques. Because the compression methods are similar, the distortion introduced into the video in the process of compression is also similar. The degree of video distortion is proportional to the degree of compression: both standards support a wide range of compression levels and, accordingly, a wide range of achievable video quality (the inverse of video distortion).


There are many metrics of video quality, some objective and some subjective. Using any measure, one can precisely demonstrate that when the compression parameters of the two standards are matched, the video quality of the same scene under like conditions is indistinguishable across a wide range of settings, with the possible exception of the extreme high-compression limit. In particular, this is easy to demonstrate using Arecont Vision's megapixel IP cameras that feature instant switching of the on-camera encoder between JPEG and H.264. In fact, if video quality was the only measure for choosing one compression standard over another it would be very difficult to make the choice.

So, if the video quality of the two standards is very much alike, then how are they different?


H.264 and JPEG: How They Are Different
The main difference between H.264 and JPEG is the consumed bandwidth per given video quality — H.264 offers a major reduction in bandwidth relative to JPEG.  Bandwidth reduction translates to a major reduction in cost of security installations: the requirements for networking equipment and disk storage are accordingly reduced.


Reduction of bandwidth is achieved at the cost of high computational complexity of the H.264 encoder. Put simply, the more computation there is, the more efficiently the data is organized and “packed.” Decoding the compressed video stream is an entirely different matter, the H.264 standard is asymmetrical: all of its computational complexity is on the encoder side while the H.264 decoder is similar in complexity to a JPEG decoder. Arecont Vision's megapixel IP cameras use a patent-pending massively parallel H.264 hardware encoder that achieves 80 billion operations per second. The high computational capacity is needed to process a large number of computational add-ons used in H.264 relative to JPEG, some of which were introduced in the earlier standards of the MPEG family to which H.264 belongs. A major departure from JPEG is that instead of encoding the video signal itself, only the inter-frame signal differences are encoded. The smaller the difference, the more economically it can be encoded into the video stream. There are two sources of inter-frame signal differences: motion in the scene and random noise.


Noise is always present, and it is notoriously difficult to compress due to its random nature. High levels of noise are typically caused by low-light conditions — they require larger bandwidth and larger disk storage space to archive.


Signal differences due to motion are much easier to compress — the majority of computational effort is typically concentrated in estimating motion. The goal of motion estimation is to locate blocks of pixels in the current video frame that closely match blocks of pixels in the previous frame corresponding to the portions of the scene that may have moved during the interval between frames. Because the direction and the distance of such movement are unknown in advance, the motion estimator must search over hundreds of possible positions to find the best match. The closer the match, the smaller is the signal difference to be encoded, and accordingly the smaller is the resultant video stream. Computational power of the motion estimator often determines the quality of the entire H.264 encoder: the larger the search area, the higher is the chance to find the best possible match. While many motion estimators conduct only an approximate non-exhaustive search to reduce the amount of computation, Arecont Vision's motion estimator conducts an exhaustive search over a large search area to find the best possible match.


Motion estimation and other computational components of H.264 compression explain its amazing ability to compress video into a low-bandwidth stream while maintaining high video quality. It is also the reason why H.264 is being embraced by broadcast television, by distributors of movies on DVD, and by many other industries including the professional security and surveillance market.
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H.264 Has No Hidden Cost
A common myth about H.264 is its so-called “hidden cost”, an erroneous belief that because the computational complexity of the H.264 encoder is very high, the required decoder resources must be high as well, many times higher than required for JPEG. The “hidden cost”, as the theory goes, is in the additional computer server power needed to decompress multiple H.264 video streams in a multi-camera security installation in order to display live video from multiple cameras. This “hidden cost” is alleged to be especially high for megapixel cameras.

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In reality, the exact opposite is true: H.264 streams encoded by Arecont Vision cameras require less computational power to decompress than JPEG streams, a fact that has been demonstrated on brand-name and open-source H.264 software decoders, such as Intel IPP and FFMPEG used by all major NVR manufacturers.
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In order to understand how this is achieved, consider that the H.264 compression standard consists of a large number of optional encoder components, each targeting its own facet of compression. Each of these optional components is capable of improving the compression by a certain amount, but every increment of improvement comes with a computational cost attached. The computational cost is incurred mainly on the encoder side, but may affect the decoder side as well, in varying degrees. Some of these components have better cost-to-effect ratio than others. By carefully choosing the subset of optional encoder components, Arecont Vision has optimized its encoder to avoid the increase in computational load on the decoder side compared to JPEG decoder. At the same time, the H.264 video stream remains fully compliant with the standard and compatible with all compliant H.264 decoders.

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As an example of computational load reduction in the decoder, consider the major computational component of the encoder — its motion estimator. According to the H.264 standard, motion estimation could be conducted at up to quarter-pixel resolution. This means that if the encoder found the best match “in-between” the original pixels, the decoder (software running on the server) has to interpolate all the intermediate pixel values and generate 16 times more pixels than there are in the original image. This operation alone would raise the computational load of the H.264 decoder way beyond the JPEG decoder level. The question is: How much benefit does it provide in terms of bandwidth reduction? In sub-megapixel low-resolution cameras, such as D1 format, this might be a valuable technique — there are relatively few pixels per foot of the scene, and accordingly the quarter-pixel precision of motion estimation makes a difference when motion is involved. However, when you consider a 5-megapixel camera, the number of pixels per foot is roughly 14 times higher than in D1 given identical optics and sensor size. It makes little sense to conduct quarter-pixel resolution search on top of the high resolution provided by the sensor itself. By avoiding the unnecessary computation both in the encoder and the decoder, Arecont Vision's cameras achieve lower cost on the camera side and maintain low computational load on the server side. Motion estimation is one example of a multitude of such strategies implemented in Arecont Vision's megapixel cameras.
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The Defacto Compression Standard
The benefits of H.264 in terms of bandwidth utilization per given video quality and the related reduction of disk storage are obvious, the incremental costs are low, and there are no “hidden” installation costs. It is safe to predict that H.264 will become the defacto compression standard for the security and surveillance market, especially for megapixel IP cameras where the benefits are even further multiplied. In fact, H.264 could be viewed as the silver bullet that has removed the earlier obstacles to mass penetration of megapixel IP cameras into the marketplace.

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Texas Instruments Demonstrates Eight Channels of H.264 Main Profile Encoding at D1 Resolution on a Single Processor

Developers benefit from lower cost per channel, system savings and simplified hardware design for NVRs, DVSs and DVRs.


Texas Instruments (TI) demonstrates eight channels of H.264 main profile encoding at D1 resolution (720 x 480 progressive at 30 frames per second (fps)) on a single processor solution. By offering this capability on a single processor, rather than current design solutions that require two or more processors, developers can reduce their bill of materials (BOM) costs. This will significantly lower the cost per D1 channel and developers can utilize a less complex hardware design to create smaller security system components such as digital video recorders (DVR) and digital video servers (DVS). This single processor offering also provides legacy codec support of MPEG-4 and JPEG encode and decode at the same density.


Developers can also combine this single processor with two of TI's new TVP5158 devices. The TVP5158 is a four-channel video decoder with flexible video outputs that removes the need for an external mux FPGA in applications requiring multiple channels, thus reducing system cost by several dollars. Additionally, a single processor solution requires less external memory and board space, providing further system savings. Developers can now benefit from these cost efficiencies and improved design flexibility for video surveillance applications such as network video recorders (NVR), DVSs, DVRs, hybrid DVRs and high-definition cameras for video conferencing.

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Great Outdoor Shootout Takes Stock of Detectors

A&S partnered with Australian remote monitoring service provider VideoControlRoom to test outdoor detectors. Michael Brown, MD of VideoControlRoom, discussed how the solutions that aim to eliminate false alarms while reliably detecting intruders fared in real life.


As VideoControlRoom moves toward “bill per event” services, it is important to prove to customers that we understand and use “world’s best practice” outdoor detection. Therefore, we decided to partner with A&S, the only trade publication with the reputation and global reach to engage the manufacturing community, and share the results for the betterment of the industry. The invitation was open to all manufacturers, and the only entry criterion was a willingness to have their products openly tested against peers.

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China's Security Market Grows Dramatically

In 2008, China's security equipment manufacturing market turned from the chaotic phase to the orderly phase, which was attributable to market competition and improvement of market order on the one hand, and to the efforts made by strong players at independent innovation and brand building on the other hand. At the same time, Olympic economy added fuel to China's intelligent building industry. At present, the security industry is evolving towards energy conservation, environmental friendliness, networking, intelligent technology, system and alliances. Enterprises are generally striving to grow in size and strength and roll out branded products.


Video monitoring remains a hot market segment. "All-in-one card" is very popular. The real estate market and community security give a notable impetus to sales of building intercom and alarm systems. With the rapid development of the integration of access control and other security systems, security products' application fields are extending.


In the face of competitions as well as market changes and challenges, the 2008-2009 Annual Report on China's Intelligent Building Market released by us will help enterprises, investors and industry insiders grasp more accurately laws governing the market's development and comb the development track of application value.

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