High-definition vs megapixel

CCTV Handbook 2013 CCTV, Surveillance & Remote Monitoring

Is there really a difference between high-definition (HD) cameras and megapixel devices? We asked two technically-oriented people active in the CCTV camera industry to give us their opinion of the HD vs megapixel debate – if indeed there really is a debate.

MJ Oosthuizen – Reditron.
MJ Oosthuizen – Reditron.

Reditron’s MJ Oosthuizen commented that HD cameras are just a different form of megapixel cameras. Below, his response on some of the differences between traditional HD and megapixel cameras.

Image sizes

There are two main resolutions for the HD specification, 720p (1280×720, just less than 1 megapixel) and 1080p (1920×1080, 2,1 megapixel). Conventional megapixel cameras often have a number of megapixel resolutions to choose from.

Picture aspect ratios

Similar to the image size, the aspect ratio of HD cameras is 16:9 whereas other megapixel cameras offer a variety of formats such as 4:3.

Frame rates

This is the biggest advantage to HD cameras over megapixel cameras. Until recently, megapixel cameras have offered very low frame rates compared to low-resolution cameras, sometimes offering as low as four frames per second compared to 30 frames per second. This has largely been due to processing power available on IP cameras as well as network restraints.

The HD standard requires footage to be created at 25 or 30 frames per second depending on location, for example the US runs at 30 frames per second while the UK runs at 25.

Progressive scan

Megapixel camera manufacturers have often used interlaced images to create megapixel footage. This essentially uses two frames to create the image. In the first frame, they capture lines 1, 3, 5, 7, etc with the second frame capture lines 2, 4, 6, etc. This can be manufactured cheaply but often causes blurred images when fast-moving objects are in view.

The HD standard requires that frames are progressively scanned. This is more expensive but provides a much clearer and crisper image.

Why does the HD format exist?

HD format was created to try and standardise the video transmissions of megapixel cameras. With HD televisions also conforming to the standard, video output can be made to any HDTV without cropping or resizing.

The HD format has worked well in forcing camera manufacturers to increase processing power and the potential of their IP cameras but conversely it may also begin to limit the development of megapixel cameras. At present, high-end megapixel cameras can be up to around 8 megapixel. If IP camera manufacturers begin to adopt the HD format for their cameras, the format will need to be updated to include higher and higher resolutions otherwise the extra detail possible at present will be lost.

There is 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. Sub streams for viewing across multiple stations allows flexible designs, while the highest resolution for reviewing can be utilised through a distributed storage architecture.

For video, there are three main fluctuating factors that contribute to bandwidth hogging of an IP camera – frame rate, resolution and compression. Any one of these factors can be throttled back to reduce the network bandwidth. For example, if you reduce the frame rate, you can increase the resolution, and vice versa.

Frames per second (FPS) describes the number of full video frames displayed or recorded within one second. Since each type of business varies, it is important to determine what requirements are needed to sustain certain defined performance parameters, such as frame rate.

Cable selection and bandwidth go hand-in-hand. Considerations when selecting the cable media include number of cameras, type of camera, location of the cameras (environment), distance to the server rooms, type of termination equipment, and whether power will be running through the cable (UTP).

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 is crystal clear that better systems are a direct result of the superior imaging possible with these high-resolution camera technologies.

Miro comments

Alex Bantjes – Miro.
Alex Bantjes – Miro.

Alex Bantjes, Miro’s brand manager for Vivotek, also weighed in on the HD/megapixel debate. Bantjes says, “High definition and megapixel are often mistakenly thought to be the same and the terms are used interchangeably. Although both terms are closely related, there is in fact a distinct difference.”

High definition, or HD, is actually a result of the analogue broadcasting/CCTV camera industry. HD simply refers to a set of standards that are used to describe the image quality of a camera as displayed on a monitor. These standards include image size, aspect ratio, frame rate and scan type. For example, the description 720P refers to the horizontal resolution of the image (16:9) and the letter P indicates progressive scan.

An image stream is defined as megapixel once the image exceeds a million pixels. The term refers to any camera with a resolution of 1280x1024 (1.3 megapixel) or higher. It should also be noted that the term 720P is not in fact the same as one megapixel, since 720P (1280x720) actually has an image of nine hundred thousand pixels or 0,9 megapixels.

Modern surveillance systems are not exclusively used to display images on monitors or television screens, output streams are required in any number of aspect ratios, image resolutions, frame rates etc. Megapixel technology is much more flexible than HD in that each output stream can be defined to optimise video for slow transmission (such as the Internet) or smaller screens (table to cellphone).

The latest advanced technologies such as adaptive streaming, where the frame rate is lowered when there is no motion in the image and then sped up to capture details of moving objects, will by definition not be available in an HD stream but only in megapixel.

In short, megapixel based system design allows for more flexible surveillance systems that can be viewed on many different types of devices at varying frame rates and resolutions. HD on the other hand is often too restrictive to meet the requirements of today’s surveillance systems.

Definitions

High-definition

* Conforms better to multimedia systems, but resolution and image format choices are more limited.

* 16:9 image format.

* Two resolutions: HD (720p) and full HD (1080p), measured by pixels of vertical resolution.

* Maximum resolution: 2.1 megapixel.

* Progressive scanning: all lines in each frame are drawn in sequence.

* Frame rate: 25/30.

Megapixel

* One million or more pixels of resolution.

* Flexible image formats: 4:3, 5:4, etc.

* Flexible resolutions: 1 to 10 megapixels (or more).

* Maximum resolution: 20 megapixels.

* Frame rate: 3-15 frames per second – can run up to 30fps on lower MP rated cameras.

MJ Oosthuizen, Reditron





Share this article:
Share via emailShare via LinkedInPrint this page



Further reading:

Smart water management
Axis Communications SA CCTV, Surveillance & Remote Monitoring Integrated Solutions
South Africa is currently facing a water crisis, with scarcity and inefficient water management posing significant challenges to sustainable, consistent access to water. Smart technology and powerful partnerships may offer a proactive solution to SA's water crisis.

Read more...
Helping retailers optimise monitoring and security
Guardian Eye Retail (Industry) CCTV, Surveillance & Remote Monitoring
From a smart retail perspective, it is crucial to understand that monitoring stock and other assets through camera surveillance and a variety of Internet of Things (IoT) sensors stretches further than the stores themselves.

Read more...
Empowering Istanbul’s public transportation
Dahua Technology South Africa CCTV, Surveillance & Remote Monitoring Integrated Solutions
Dahua's intelligent transportation solution, using technologies like DSM and AI-based passenger flow counting, has facilitated an intelligent system upgrade for nearly 6 400 minibuses and electric buses in Istanbul.

Read more...
Smart manufacturing redefined
Hikvision South Africa CCTV, Surveillance & Remote Monitoring Industrial (Industry)
AI and intuitive visualisation technology allows managers to monitor manufacturing sites, production, and operational processes, and to respond in real time in the event of an issue – helping to drive efficiency and productivity.

Read more...
AI is getting smarter, and critical infrastructure is set to benefit
Axis Communications SA CCTV, Surveillance & Remote Monitoring
With technology advancing at an astonishing pace, AI has emerged as a defining trend in today's business arena. Enterprises across all sectors are prioritising this technology, embracing its transformative potential to drive change and growth.

Read more...
Collaboration delivers integrated and holistic security
Guardian Eye CCTV, Surveillance & Remote Monitoring News Integrated Solutions
Guardian Eye and Lytehouse have partnered to integrate their speciality solutions and provide a holistic security offering that overcomes the fragmentation of security systems and services.

Read more...
Manage security systems remotely
Hikvision South Africa CCTV, Surveillance & Remote Monitoring IT infrastructure Products
Hikvision launched a new generation of smart managed switches that, in conjunction with the Hik-Partner Pro mobile app, enable installers to remotely deploy and configure security systems with comprehensive operation and maintenance capabilities.

Read more...
Synology enhances functions for advanced surveillance integration
Technews Publishing CCTV, Surveillance & Remote Monitoring IT infrastructure Products
With the capability to function as both an API client and server, Surveillance Station offers a versatile platform for integration, whether it's embedding video streams into other platforms or overlaying external data onto recorded video.

Read more...
SMART Surveillance Conference 2023
Technews Publishing Editor's Choice CCTV, Surveillance & Remote Monitoring Conferences & Events
Some people think the future is all about cloud technologies, but the SMART Surveillance conference demonstrated that AI is making edge surveillance much more attractive, over distributed sites, than ever before.

Read more...
Supporting CCTV intelligence with small and big data
Leaderware Editor's Choice CCTV, Surveillance & Remote Monitoring
The increasing development of AI and its role in enhancing investigation-led surveillance, and the increasing capacity of control rooms and local analysts to deliver data in return, can increase the synergy between intelligence and surveillance.

Read more...