Defining Resolution
High-definition and megapixel cameras are clearly not the same
- By Raul Calderon
- Sep 01, 2011
As IP-based video systems continue to gain widespread popularity in the video surveillance market, one of the benefits is the ability to capture highresolution images through megapixel video. Also emerging is conformity with HDTV standards prevalent in the consumer video market. The images this new generation of cameras produce are often collectively referred to as high-definition or as megapixel images.
Because the terms HD and megapixel both indicate an improved level of imaging performance compared to traditional analog images, the terms 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 about 1.3 megapixels, which provide 1280x1024p resolution, or 1.3 million pixels, to resolutions as high as 10 megapixels (3,648x2,752p). The range of megapixel cameras continues to expand to accommodate various application requirements. For example, Recent Vision has expanded its range of megapixel cameras to include a 1080p and two, three, five, eight and 10 megapixel offerings, and soon 20 megapixel solutions.
HD refers to cameras with a standardized resolution of 720p or 1080p. The numbers 720 and 1080 refer to the horizontal resolution. Therefore, a 720p HD camera resolution provides images that are 1280x720p (921,600 pixels—not a full megapixel), and 1080p HD cameras provide 1920x1080p 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 standardized at 60, 50, 30 or 25 fps (depending on your TV).
IP Video Systems Have Momentum
According to a report by Technetium Insights, IP surveillance is poised for significant growth among end users and large organizations. The benefits of softwaredriven functionality and the control, scalability and broad availability of video are often listed as factors contributing to this growth. However, among the biggest performance features of IP surveillance is the ability to provide a broad range of video resolutions. With H.264 compression, 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 (3,648x2,752 pixels—nearly five times the resolution of a 1080p camera).
Because users can adjust today’s megapixel cameras to specific surveillance locations at different resolutions, they can combine cameras of varying resolutions on the same network. Core areas can then be viewed and recorded at a higher resolution while secondary areas are viewed at a lower 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 optimize existing network pipelines as well as recorder storage space.
Megapixel cameras’ higher resolution 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 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 increased cabling costs exponentially. However, networking infrastructure enables users to connect multiple cameras with fewer cables, and PoE supplies power to cameras on the same Cat-5 cables as video and control signals, rather than requiring localized power or a distributed power supply. It’s an efficient and simple installation solution.
Additionally, the superior resolution provided by megapixel cameras enables detailed and accurate digital PTZ 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 end users have the false perception that IP megapixel systems are too complicated to deploy. It’s true these systems are not plug-andplay in the traditional sense, but partnerships between camera suppliers such as Recent 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 plugand- play with little or no programming more of a possibility. Additionally, there’s a wide range of megapixel cameras available 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.
The Move to Megapixel
The developments in 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. The ability to use fewer megapixel cameras to cover larger areas than analog cameras could result in savings on infrastructure and labor 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, for your specific needs, the wide range of high-resolution cameras 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.
This article originally appeared in the issue of .