High-Definition and megapixel resolution are clearly not the same, writes Paul Taggar, pictured, Country Manager, UK and Ireland, for the US manufacturer Arecont Vision.
As IP-based video systems continue to gain widespread popularity in the video market, one of the benefits is the ability to capture high-resolution images through megapixel video. Also emerging is use of the HDTV standards that are prevalent in the consumer video market. The images produced by this new generation of cameras are often collectively referred to as high-definition (HD) or as megapixel images. Because the terms HD and megapixel both indicate an improved level of imaging performance compared to traditional analog images, they are often thought to be the same. But, there is a difference.
In fact, the broadcast (or consumer) HD resolution should not be seen as the goal in video surveillance. Megapixel cameras offer resolution higher than broadcast HD resolution, thus, an explanation is in order.
Megapixel versus HD
One could consider HD a subset of megapixel. HD is defined by specific resolutions at specific frame rates with a specific aspect ratio. Any camera with a resolution of more than a million pixels is by definition a megapixel camera. The lowest resolution in the megapixel range in the security market is around 1.3 megapixels, which provides 1280 x 1024-pixel resolution (or 1.3 million pixels), to resolutions as high as 10 megapixels (3,648 x 2,752 pixels). The range of megapixel cameras continues to expand to accommodate various application requirements. For example, Arecont Vision has expanded its range of megapixel cameras to include 1.3, 1080p, 2, 3, 5, 8, 10, 12, 20 megapixel offerings, and now up to 40 megapixel solutions.
HD refers to cameras with a standardised resolution of 720p or 1080p. The numbers 720 and 1080 refer to the horizontal resolution. Therefore, 720p HD camera resolution provides images that are 1280 x 720 pixels (921,600 pixels — not megapixel), and 1080p HD cameras provide 1920 x 1080-pixel resolution, or 2.1 megapixels. The HD video format also uses an aspect ratio of 16:9 (rather than 5:4 or 4:3), and the frame rate is standardised at 60, 50, 30 or 25 fps (depending on your TV).
IP video systems
According to a US report by TechNavio Insights, IP is poised for significant growth among end-users and large organizations. The benefits of software-driven functionality and the control, scalability and broad availability of video are often listed as factors. However, among the biggest performance features of IP is the ability to provide a broad range of video resolutions. With H.264 compression and programmable resolutions and streaming, the new standard for video resolution can be defined simply as ‘whatever the application calls for’. With IP/megapixel video, cameras assigned to cover critical areas can now capture any level of resolution up to 10 megapixel images (3,648 x 2,752 pixels – nearly five-times the resolution of a 1080p camera).
With the ability of megapixel cameras to be adjusted to specific locations at different resolutions, cameras of varying resolutions can be combined on the same network. Core areas can then be viewed and recorded with higher resolution quality while secondary areas are viewed at less resolution with slower frame rates. Video analytics can also be applied to trigger megapixel streaming only when automatically activated. This approach conserves valuable bandwidth to optimise network pipelines as well as recorder storage space.
The higher resolution provided by megapixel cameras also allows system designers to use fewer cameras to cover larger areas without losing detail, and with reduced infrastructure and cabling costs. In addition to reducing the initial installation costs of a system, these benefits translate directly into greater return-on-investment (RoI) and lower total cost of ownership.
Resolution performance versatility is just one of the advantages of IP megapixel video. Another contributing factor to the rapid rise of IP megapixel imaging is the ease of network system connectivity. In the old days, every single camera had to have a ‘home run’ coaxial cable running to the recorder, which increases cabling costs exponentially. However, networking infrastructure enables connection of multiple cameras with fewer cables, and the use of Power-over-Ethernet (PoE) even allows power to be supplied to cameras on the same CAT-5 cables as video and control signals (rather than needing localised power or a distributed power supply). It’s a very efficient and simple installation solution.
The superior resolution provided by megapixel cameras enables highly detailed and accurate digital PTZ (pan-tilt-zoom) of live and recorded images. As a result, megapixel cameras virtually eliminate the need for mechanical PTZ cameras, which are often costly and feature mechanical parts prone to failure.
Many integrators (and users) have a false perception that IP megapixel systems are too complicated to deploy. It’s true these systems are not plug-and-play in the traditional sense, but partnerships between camera suppliers such as Arecont Vision and various DVR and VMS suppliers have paved the way for simplified integration of systems that meet the definition of plug-and-play on an IP network. Standards initiatives such as PSIA and ONVIF are making plug-and-play with little or no programming more of a possibility. Additionally, there’s a wide range of megapixel cameras available today with selectable resolution and frame rates that are ideal for general surveillance applications. These options provide system designers with a high degree of flexibility and confidence in their designs.
Move to megapixel
The developments related to H.264 video compression make bandwidth and storage requirements of megapixel images in IP-based systems comparable to those of standard resolution images. Megapixel cameras are also comparable in price to standard-resolution cameras. When you consider the ability to use fewer megapixel cameras to cover larger areas than analogue cameras, the result is a related savings on infrastructure and labour costs. These are all reasons why IMS Research predicts a significant increase in the installation of networked video surveillance systems, and that more than half the network cameras shipped by 2014 will be high-definition or megapixel resolution.
Whether you prefer megapixel cameras or its subset HD based on your specific needs, the wide range of high resolution cameras today provides a powerful palette of imaging tools for industry professionals. It’s crystal clear that better systems are a direct result of the superior imaging possible with these high-resolution camera technologies.
