720p and 1080p explained

720p explained

720p is the shorthand name for a category of HDTV video modes. The number 720 stands for the 720 horizontal scan lines of display resolution (also known as 720 pixels of vertical resolution), while the letter p stands for progressive scan or non-interlaced.

Progressive scanning reduces the need to prevent flicker by filtering out fine details, so sharpness is much closer to 1080i than the number of scan lines would suggest. A 720p frame has about 1 million pixels. Compared to it, a 1080p frame has 2 million pixels so the amount of detail doubles. However in practice the difference between 1080p vs 720p is not as obvious as the one between standard definition vs high definition (480p vs 720p). For example a regular DVD isn’t even considered high definition because it is either 720×480 (NTSC) or 720×576 (PAL) but it looks much better than regular NTSC or PAL TV broadcasts and not as great as 720p. That being said, you do get more detail from 1080p than from any resolution if you have the “winning” formula for screen size, resolution and viewing distance – that is if you have the optimum conditions to get the most out of 1080p.

1080p explained:
The number 1080 represents 1,080 lines of vertical resolutions (1,080 horizontal scan lines), while the letter p stands for progressive scan (meaning the image is not interlaced). 1080p can be referred to as full HD or full high definition although 1080i is also “Full HD” (1920×1080 pixels). The term usually assumes a widescreen aspect ratio of 16:9, implying a horizontal resolution of 1920 pixels. This creates a frame resolution of 1920×1080, or 2,073,600 pixels in total.

The only pure 1080p content comes from high definition DVDs like Blue Ray and HD DVD. Regular DVDs are way below that, having just 480p or 576p. You also get HD content from TV broadcasts but for now only 1080i and 720p. Basically 1080i offers pretty much the same amount of detail as 1080p but the quality of fast moving scenes is a bit inferior to 1080p. To understand this better read the 1080p vs 1080i guide. 720p content will of course look the same (or very similar) on a 1080p screen as it does on a 720p screen because what also matters is the content resolution not just the screen resolution.

Here is a sample with the difference between 720p and 1080p:

480i - Total image resolution 337,920 pixels

480p - Total image resolution 337,920 pixels

720p - Total image resolution 921,600 pixels (roughly equivalent to a 1 mega pixel camera)

1080i - Total image resolution 2,073,600 pixels (equivalent to a 2 mega pixel camera)

1080p - Total image resolution 2,073,600 pixels (equivalent to a 2 mega pixel camera)

More lines is nice but don't forget about the 'p' and 'i' in the 720p, 1080i and 1080p. The letter is an abbreviation for the type of scan the TV uses -- 'p' stands for progressive and 'i' stands for interlaced.

HD-SDI High Definition CCTV vs Traditional CCTV Cameras

HD-SDI CCTV cameras, also known as HD security cameras, are quickly gaining popularity as a high definition video surveillance solution. Until a few years ago, the only available option for high definition surveillance systems was to use network IP cameras which are typically more expensive and almost always more difficult to setup.

With the advent of HD-SDI technology for security cameras, users can now capture 1080p resolution video using the same RG59 or RG6 coaxial cable that is used by traditional CCTV cameras.

This new SDI platform is pivotal information for existing CCTV users whom have invested into expensive coaxial cabling installations, and now are in the market to upgrade their system to HD. These users are able to leverage their existing coax cable when they upgrade to HD Security cameras.

The HD-SDI paradigm also makes installation easier for many low voltage installers because HD-SDI security cameras follow the same plug and play processes as the traditional CCTV cameras, unlike IP cameras, which do require some level of networking knowledge to setup.

HD-SDI Camera vs. CCTV Camera Resolution

Traditional CCTV cameras are capable of resolutions up to about 704 x 480, which is referred to as D1 resolution, which is a hard limit that analog CCTV DVRs must abide by.

Some traditional CCTV cameras can actually capture slightly larger images than D1, but are unable to take advantage because traditional CCTV DVRs are limited to 704 x 480 resolution, which is why D1 is the accepted max resolution in the CCTV industry.

HD-SDI CCTV cameras are capable of true HD 1080p resolution (1920 x 1080). This higher resolution is the same as a high definition television and movies that consumers are use to. The SDI technology behind HD-SDI CCTV cameras is the same as the video cameras that capture video footage for “high def” motion pictures.

Here are the original images used in the above illustration. This high definition image was captured using a HD-B20 dome HD security camera.

This is the image captures with traditional CCTV camera. A DPRO-9620 model CCTV camera was used to capture this image at D1 resolution (704 x 480).

HD-SDI and CCTV Images

The following image compares the image size and resolution of a high definition HD-SDI CCTV camera and standard definition CCTV camera. Please click on the image for the full sized view. After you click on the image, if your web browser supports zooming, you will probably be able to make the image even larger.

The benefits of HD-SDI CCTV are:

• High Definition images, making it easier to identify individuals.

• Simple installation using standard co-ax cable.

• No need to involve IT Managers as part of the installation.

HD-SDI is significantly easier for experienced CCTV installers to get to grips with and can easily be used in tandem with existing analogue cameras. Compared with IP, installers can install HD-SDI straight away with next to no training. There is also very little risk of getting in to complications when installing it, as long as they are experienced in installing analogue CCTV. With an increasing demand for HD CCTV footage the standards that end users expect are growing.
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