The real truth about megapixels & HD

Megapixels, high-definition, aspect ratios, H.264, compression algorithms, lines of resolution, storage-it's enough to make a person's head spin. Coupled with all the other terminology and technology you need to learn to properly specify a video/IP/CCTV installation and you may feel like throwing in the towel.

That won't be necessary if you have an open mind and a willingness to learn. In fact, the recent mantra at the largest security show of the year, ISC West, was a battle cry by exhibitors who realize that this is the time when the systems integrators need their assistance big time-in the way of education, white papers, specifications and training to get their arms around it all.

We went to manufacturers and posed the following question: "what are one to two important distinctions integrators should know about megapixels and HD?" Here's what they said:

Sara Scroggins-Product Marketing Manager-Pelco (Schneider Electric), Clovis, Calif.

"Generally speaking, "high def" or HD imaging is considered to be video that has 1 million pixels-1 megapixel or 1MP-or more, but really can be anything above Standard Definition (SD). More pixels mean more clarity and the more detail within a given scene adds to the ability to identify people and other items of importance. For example, the ability to identify vehicle license plates could prove especially beneficial in certain situations.

HD gives customers more detail in order to digitally zoom in on video after footage has been taken while maintaining the ability to have clear images. This is possible without significantly degrading the image clarity as in the case of SD. The higher the resolution, the greater the detail you can achieve with digital zoom.

When we use the term HD imaging, what we are referring to are actually standards used within television broadcasting. Megapixel simply describes the total resolution of the capture system and has more latitude with regard to transmission, frame-rate and other specifications one might find in the strict definition of HD.

HD serves as a good definition in that it not only provides a resolution requirement but it also provides information regarding the frame rate and aspect ratios; whereas the term megapixel, which we also use in the security industry, simply describes the resolution size. So, in actuality you can have mixtures of both, where you may have megapixel resolution and HD, but when we talk about megapixel it is referring to the horizontal and vertical resolution."

Ed Thompson-Chief Technology Officer-DVTel Inc.-Ridgefield Park, N.J.

"It's important for systems integrators to know that generally all HD cameras qualify as megapixel cameras, however not all megapixel cameras support the HD standards. HD is standards based technology developed for motion pictures and HD broadcast while megapixel cameras only need to support more than 1 million pixels to qualify as an MP camera. The HD standard specifies the aspect ratio to be 16:9 wide screen vs. 4:3 used in legacy SD and megapixel cameras as well as color reproduction and encoding quality.

The advantage of HD is wide-screen capture, or wider field of view. This is a significant enhancement for numerous surveillance applications, because the typical camera captures a lot of sky and ceiling. With megapixel cameras, these images only get wider and wider, so incorporating HD standards in a megapixel camera helps to offset that fundamental issue.

Mark S. Wilson-Vice President, Marketing- Infinova, Monmouth Junction, N.J.

"Today, more and more end-users are asking for megapixel cameras and wanting H.264 compression. The verticals leading the charge into using megapixel and HD cameras are transportation hubs (especially on concourses), warehouses, all types of lobbies and other high-incident locales. Often, though, they do not realize the impact this will have on their systems. Megapixel cameras, including HD, have more than 1,000,000 pixels compared with analog cameras which have less than 400,000 pixels. There are three important factors to remember when considering the use of HD megapixel cameras:

1- H.264, a better compression technology, requires less bandwidth and storage capacity. That's good.
2- H. 264 requires more processing power. That's not so good.
3- Since H.264 has a higher resolution, it requires a higher resolution display. That's not a big issue unless you don't follow through.

So, although H.264 needs less bandwidth and storage capacity, it does bring some negatives. Some are in the process of being overcome. For instance, PC graphics cards are moving quickly to the H.264 standard and video management software vendors are making vast improvements in H.264 processing so that, eventually, the industry will overcome this particular drawback...just not yet! Today, when viewing multiple cameras simultaneously, over-configure the servers in the control room to cope with the more intensive processing requirements. Or, remember, although M-JPEG does not yield the bandwidth and storage savings when compared to H.264, M-JPEG does not require as powerful PCs or processors.

Another issue is standards. Too often, H.264 is implemented in a proprietary manner by camera manufacturers. Video Management Software (VMS) vendors simply can't support all the 'flavors' of H.264. Be sure that the cameras selected are fully supported by the VMS vendor and that they support the full range of features provided by the camera."

Alan Schwartz-Product Manager-EverFocus, Duarte, Calif.

"Terminology is SO important, as I'm sure the folks at Coke, Kleenex and Frigidaire would agree. For years, when we said 'CCTV,' it did not matter if you thought of it as 'video' 'composite' or 'NTSC/PAL,' we knew what we meant. Then, with the advent of local and wide area networking, we found black boxes that convert the 'analog' video signals into digital data and transmit that data over local and wide area networks to other black boxes which convert the digital data back to its original 'analog' form for display and/or recording on CCTV equipment.

It has been transparent to the average dealer/installer or end-user, but for many years now 90 percent of the video within an 'analog' camera-from the CCD sensor, through the signal processing and controls/menu system-is all digital data. Only at the very end of the process is the digital data converted to NTSC/PAL 'analog video' and delivered at the BNC connector on the camera.

In parallel with this, technology developed sensors capable of capturing images with much higher resolution, much greater data content, than 'standard definition NTSC/PAL' video. Why not put these sensors into our CCTV cameras and improve the pictures? Those international standards for the transmission of video (NTSC & PAL) were defined to handle only a specific, limited amount of bandwidth, which translates to the maximum amount of data/information they can carry. The information content in a high resolution image is more than 'standard analog' video is designed to handle.

What if we don't plan to convert the signal to NTSC/PAL? We're no longer bound by those bandwidth and resolution limitations: we can support any resolution sensor that the data transport medium can handle. IP (typically TCP/IP Ethernet) networks run at least 10Mb/s, frequently 100Mb/s or more.

As a benchmark, a nominal NTSC picture can be represented on a computer monitor in a digital image comprised of 345,600 dots or pixels (Picture Elements) arranged in 480 rows of 720 pixels per row. PAL is 768x564 pixels.

Free of the bandwidth restrictions of NTSC/PAL, we can utilize sensors with more pixels to achieve finer detail and higher resolution. As we saw early on with consumer digital cameras, resolutions of 1280x1024 are readily available: 1,310,720 pixels, or 1.3 megapixels. Enter the megapixel camera. How do we transport that amount of data? At the advent of this technology, IP networks were the only available medium, so there were only IP megapixel cameras. While an IP camera need not be a megapixel camera, there was a point in time where a megapixel camera was automatically an IP camera. Needed megapixel? Had to go IP!

With the advent of HDTV (1080p translates to 1920 x 1080 pixels, or 2,073,600 pixels - about 2 megapixels; 720p translates to 1280 x 720 = 921,600 pixels or ~1 megapixel), the broadcast industry developed protocols to transmit HDTV over coax, called high definition-serial digital interface (HD-SDI), standardized in SMPTE 292M (Society of Motion Picture and Television Engineers); this describes a nominal data rate of 1.485 Gbit/s over coax, terminated with BNC connectors.

So, with a protocol defined to transmit high definition (1 and 2 megapixel) signals over coax (of which coincidentally there are millions of installed runs with BNC connectors at both ends, a standard definition camera at one end and a recorder at the other end) enter an alternative protocol for transmission of megapixel video images: HD-CCTV. EverFocus saw the potential for HD-CCTV and supported the initiative by becoming a founding member of the HD-CCTV Alliance.

Today, while an IP camera may or may not be a megapixel camera, a megapixel camera may or may not be an IP camera! It may be an HD-CCTV camera-and an HD-CCTV camera is always a megapixel (720p or 1080i) camera."

Steve Gorski-General Manager for the Americas-MOBOTIX Corp., New York, N.Y.

"HDTV is a widely adopted standard that is well-suited to the application for which it was originally designed--consumer entertainment. HDTV has a maximum 1920 x 1080 resolution made possible with the implementation of H.264. Ideal for watching movies from devices such as an iPhone or Blu-ray player, the H.264 codec scales extremely well, from small screen to widescreen HD cinematic viewing. However, the key strength of H.264, low bandwidth streaming, is in fact its greatest weakness when used for the purposes of video surveillance. Why is this the case? First of all it is important to note that when it comes to capturing video from a security camera, what's most importance are the areas where changes or movement occurs. H.264 actually displays movement in such a way that looks very good to the eye, but only while streaming. When pausing the video and extracting still images for the purposes of object or facial identification, the still images tend to look blurry and lack detail. This is because H.264 applies a lot of compression to any changes in the scene - hence the reason why it is so bandwidth efficient. This is ideal for watching movies, because the human eye can't detect the loss of quality where there is movement in each frame, but not suitable for surveillance applications.

From the outset, it was clear to MOBOTIX that what customers want is the ability to be able to pause the video at any place in the stream and extract high quality stills to positively identify the moving object or person. MPEG based codecs, such as H.264, simply do not fulfill this requirement.

MOBOTIX has in fact, created a video delivery technology called MxPEG that is, to date, the world's first and only codec specifically designed for security applications. The patented technology enables the extraction of stills for positive identification, without any compromise of image quality - no blurring and no loss of detail. It also goes one step further, delivering the best of both worlds--bandwidth efficiency plus higher quality video streaming and image stills. No other video technology in the surveillance market delivers that combination. MxPEG currently offers 2048 x 1536 image resolution which is 51 percent higher than HDTV. In fact, MxPEG is a key contributing factor as to why MOBOTIX owns nearly 40 percent global share of the high resolution IP camera market segment."

Paul Bodell-Chief Marketing Officer-IQinVision, San Juan Capistrano, Calif.

"According to Wikipedia, 'HD video refers to any video system of higher resolution than standard-definition (SD) video and most commonly involves display resolutions of 1280x720 pixels (720p) or 1920x1080 pixels (1080i/1080p).'

A number of manufacturers who are lacking in megapixel products would have you believe HD is something different or somehow better than megapixel. Truth is, HD is just marketing. In our experience, here is what most people assume about HD:

1- It is widescreen format (16:9), not standard format (4:3)
2- It is H.264
3- It is high frame rate

The reality is that megapixel cameras have been able to deliver widescreen format, H.264, and a high frame rate for years now, they just weren't marketed as HD.

The key questions integrators should ask when they are evaluating 'HD' camera technology are:

1- What is the resolution in pixels (i.e. HD720 = 1280 x 720 = 0.92 Megapixels)?
2- Is it progressive scan (HD1080p) or interlaced (HD1080i)?
3- At what frame rate does it deliver at full resolution? Some manufacturers will say 'up to 1080p at up to 30fps.' If you do a little digging, you will find it is either/or but not both.
4-What 'Profile' H.264 compression does it use? If you hear 'Constrained Baseline Profile' or 'Baseline Profile' expect YouTube quality video. If you need security quality video, then accept nothing less than 'Main Profile' H.264 cameras."

Mark Gally-Vice President of Marketing-VideoIQ-Bedford, Mass.

"The most important thing for integrators to know is that HD implies a specific megapixel aspect ratio, frame rate and resolution (16x9 aspect ratio at 30fps with either a 720p or 1080p resolution). Because HD designates a subset of megapixel options, integrators should also know that other aspect ratios, frame rates and resolutions are available that may, or may not, suit a customer's situation better than HD.

Important considerations when selecting the appropriate megapixel camera for an application include aspect ratios, frame rates, frame type and resolution. For example, 1.0MP and 2.1MP cameras, typical deliver 16x9 aspect ratios while 3.0MP and 5.0MP cameras deliver 4x3 aspect ratios. Therefore, integrators should consider whether a wider aspect ratio is in fact best for the specific application. Similarly, progressive, or 'P' cameras deliver full frame rate while interlace cameras, typically designated 'I' alternate between even and odd horizontal lines each frame-therefore delivering only half the stated frame rate. And finally, what resolution is most appropriate for a customer's application?"

3 Tips for Integrators

1.High definition surveillance is a network-camera technology, meaning that it cannot be used in older, analog CCTV applications. What HD offers is the ability to dramatically improve resolution of surveillance images so that users will no longer experience the grainy, pixilated images they have traditionally seen.

2. Several new technologies are involved with network HD cameras today. Chief among them is the use of the new H.264 compression technology which combines built-in audio synchronization, dramatically improved compression of HD Images, and intelligent predictive motion analytics to eliminate the "halo" effect seen on older compression technologies like MPEG-4.

3. Select the right encoding format for the intended use, H.264 for video monitoring and MPEG for vivid, high resolution image recording. -- Robert M. Gailing, National Sales Manager, Security Products, SANYO North America, Chatsworth, Calif.

HDcctv Alliance

According to the HDcctv Alliance (www.highdefcctv.org), High-Definition Closed Circuit Television, or HDcctv transmits uncompressed and without being encapsulated in TCP/IP. HDcctv hopes to bring all of the benefits claimed by megapixel IP cameras to the CCTV market with the ease of use of conventional analog CCTV equipment. It's designed to be a drop-in replacement for existing analog CCTV, requiring only a change of camera and receiver. It digitally transmits full HD HDTV signals.

 

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