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21. HD - High Definition

Submitted by Testing on Mon, 09/07/2015 - 07:34

Up to now, TV, video DVD etc. was only available in standard resolution, which is not very good at all. As mentioned before, video resolution is dependent on the colour format and carrier (VHS, DVD, and Broadcast) used and can vary widely. Even the best versions of standard resolution TV are still rather weak and limited in the amount of detail. HDTV or HD gives the user far more detail than before and can therefore display an image with far more detail and clarity than ever before. HDTV is the latest development in TV display technology. It significantly increases the resolution over old, analogue signals and relies on new digital display technologies such as LCD an Plasma to give the user much more detail than ever before on his or her TV.

Below is an example of an image with standard resolution.

Now, observe the image below, with high definition levels of detail.

High Definition generally carries twice the amount of detail that standard resolution images carry. Notice the smoother curves and how more of the actual shape can be shown. This is exactly why HD is so much better than standard resolution.

At first, the most commonly available HD contents will be broadcast (1080i or 720p) and BluRay (1080p), this will change in time to also include HD home videos and internet downloads.

Requirements for HD

1] A 16:9 aspect ratio screen.

HDTV only broadcasts in 16:9 and therefore and conventional 4:3 screen will not be capable to display HDTV in full resolution.

2] A screen that has more than a million pixels.

The two most common HDTV formats are 720p and 1080i. Both numbers refer to the number of horizontal lines in the picture. I and p refer to the scanning type (more on that later). The pixel count for 720p is: 1280 x 720 pixels and for 1080i is: 1920 x 1080 pixels. Although "true" HD is defined as 1920 x 1080, there is also an intermediate format of 1280 x 720, which is also regarded as HD. Some manufacturers also use a panel of 1024 x 768, which even though it is not quite 1080 in horizontal resolution, it can display HD virtually uncompressed and can is regarded as the entry point to HD.

3] An HDTV source.

Most countries have begun experimental broadcasts of HDTV and some like the USA , Europe and Japan have a number of commercially available HD channels. There are currently a number of ways of obtaining a proper HD signal, namely: HD broadcast , HDDVD and Microsoft HD video clip download.

4] An HDTV connection between the screen and the monitor.

All old analogue formats such as composite video, s-video, component video and RGB video, are obsolete with HDTV. The only way of getting a HDTV signal to the screen is via a digital connection such as either DVi or HDMI . No other way will work.

Do I need one?

HDTV's will become a "must have" item in most households soon, offering picture quality many times the resolution to previous analogue TV's. Although broadcasts are still very much at experimental stage, customers will be kicking themselves in a year or two, as broadcasts become more readily available. Also, as technologies become intertwined and all types of systems converge, a TV screen is no longer a stand-alone entity. TV games, computer files, internet downloads, digital sources like still cameras, video cameras, and HD recorders will become part of the entertainment environment and therefore the display system needs to be up to the task of displaying all of the abovementioned sources at the original high resolution.

What is the difference between HDTV and DTV?

DTV is the newer format of digitally transmitting TV signals the world over and receiving them with a set top box via cable or satellite. Although this is far preferable to the old analogue transmissions, it still of standard resolution. HDTV is of much higher resolution and although all HDTV is digital, not all DTV is high definition.

HDTV "compatible"

Many suppliers are now exploiting the limited knowledge of the public (and some dealers) and are selling screens as "HDTV compatible". THIS MEANS THAT IT IS NOT A HDTV SCREEN! A digital board inside such a device reduces the resolution in the HD signal and displays it on the standard resolution display panel.

HDTV "ready"

This logo refers to a panel that can display the actual HD resolution of the signal as the panel has a resolution of over a million and is in a 16:9 aspect ratio, but has no HD tuner on board. Such a device relies on the source component to supply the panel with a digital high resolution signal.