Why many people prefer HDTV to standard analog TV is the former’ ability to provide superior picture quality which is so visible to any viewer. When you watch HDTV, the picture looks much clearer, sharper and more-detailed. Added to these qualities, you will find HDTV offers extra-ordinary smoothness, rich colour tones, superb, true-to-life colours and three-dimensional sound effects. With a HDTV television, you usually get various connections that include S-video, AV input, HDMI inputs, SCART inputs, PC input and even a USB slot to connect camrecorders, digital cameras and so on.

However, the optimum results of a HDTV television largely depend upon the video source that is connected to it. Usually HDTV sources like HDTV broadcast, HDVD or Blu-ray discs offer excellent picture quality. Also it should be born in mind that the HDTV-enabled television set should be compatible with the input devices used and sometimes both the devices need to use proper settings to ensure the best HD picture quality.

HDTV Vs Analog TV
HDTV broadcast is digital in contrast to standard TV broadcast which is analog. Analog TV signals, when interfered or when they become weak, they usually produce pictures which appear rolling from bottom to top over the screen. This is what is generally called vertical rolling. However, HD broadcast does not exhibit these effects on the screen when the signals get interrupted. In such circumstances, HD signals stops showing picture in herringbone patterns and usually show a frozen image till the signals become normal.

Being digital, HDTV broadcast does not display fuzzy pictures or over-lapping images or gitters like old analog signals.

HDTV has wider images
One of the distinct features of HD picture is its 16:9 format which refers to its dimensions in terms of width and height. HD shows picture whose width is nearly twice the height, so the image looks rectangular compared to standard 4:3 image which appears a bit squarish by contrast. Standard television screens and older movies usually have 4:3 aspect ratio which makes the screen look square like. When movies were made in 35mm or 16 mm films, this aspect ratio was the standard as they both matched well to provide a satisfying TV viewing experience for viewers. However, the rise of 70 mm movies and its growing popularity in the last three decades, made the TV makers to adopt a new image aspect which can produce theatre-like image quality.

The major advantage of 16:9 image format is its ability to show extra details on either side (horizontally) when compared with the standard 4:3 image. This is like a panoramic view which is used in a camera. The extra width that a HDTV has, provides life-like picture quality to what we see on the screen.   Thus, the 16:9 aspect ratio of the image became standard for HDTV although all HDTVs are capable of showing 4:3 image using their zooming feature which can fit such images to their screen size.

When you watch movies (which are shot using 70 mm films) on standard analog TVs, the picture is made to fit to its square frame either by cutting the extra width of the original image or by using a method called ‘letter box”. In the first case, you will see a cropped image which will lose picture details on either side. If the ‘letter box’ is used, you will see a dimensionally-reduced, rectangular image with horizontal black bars both at the top and bottom of the image. However, HDTV, since its screen has 16:9 aspect ratio, shows the original image with all picture details.   

Superior picture quality
No other digital TV can show as much true-to-life colours as a HDTV can. This is because HDTV signals can store much more information or details which is usually expressed as bandwidth. Typical HDTV can show as many as five times more details than a standard TV picture. It can display billions of colours and since the scanning lines are so close to the extent that they are hardly visible to the viewer, the picture looks razor-sharp and much more detailed than any other image. Remember a HDTV screen can accommodate more than two million pixels or picture details which is ten times greater than standard television set. This is the major reason why HDTV picture looks crisp clear combining the natural colours with superior picture details.

HDTV images are sharper
The resolution or the picture details of an image is expressed by presence of tiny dots (or pixels) in a square area. The resolution of HDTV is usually denoted by number of lines followed by the letter ‘I’ or ‘p’. These letters tell us how the image is being scanned – whether interlaced or progressively.

Although a typical Standard definition Television (which is analog) has better resolution (330 lines) than a VHS recording or a video captured using a VCR (240 lines), it is still quite far behind a DVD in terms of resolution. A DVD is a digitally recorded video which can show better resolution (480 lines) than a standard analog television set, which is why DVDs require better display than a standard television set. In contrast, a HDTV is capable of showing minimum 720 lines thus it can outperform both analog TV and other digital TVs as far as resolution is concerned.    

Progressive images have better quality than interlaced images as interlaced scanning display all the scanned lines in two frames while progressive scanning does the same at one stroke thus reducing the screen refresh rate. Due to this, a standard HDTV which has a resolution of 720p can show pictures superb picture details combined with excellent smoothness.

HDTV can provide theatre-like audio quality
HDTV offers better sound quality as most HDTV sets feature Dolby Digital 5.1 surround sound which uses five sound tracks instead of two and which is normally adopted by movies. Compared to this, standard television sets use old Dolby surround to produce stereo-phonic effects and the sound quality produced by Dolby Surround is usually a bit inferior to its advanced version as it uses just two sound tracks.

Standard Definition TV (SDTV), Enhanced Definition TV (EDTV) and High Definition TV (HDTV) represent the evolution of TV over the period since J.L. Baird invented the first ever television in 1936. Standard Definition TVs have less than 480 lines of resolution and can display images at 4:3 format. In contrast, EDTVs are digital and have a minimum resolution of 480 lines but less than 720 lines of resolution. An EDTV image can have either 4:3 aspect ratio or wider aspect ratio (16:9). DVD is an example for EDTV source since it has a resolution of 480 lines (or 480 pixels when the image is scanned vertically).

However, HDTV, which is digital and has a standard 16:9 aspect ratio, can show the highest resolution up to 1080p (which provides picture quality than 1080i image). Despite its ability to provide the image quality in terms of sharpness, natural colours and smoothness, HDTV display invariably depends on video sources it is connected to. If the video sources are too HDTV and configured to the TV, we get true HDTV viewing experience. What happens when you receive SDTV signals through your HDTV-enabled television set? The answer is your HDTV still shows the picture depending on the source as it cannot enhance the original picture quality. On the contrary, if you are in a place where you can get HDTV broadcast either via cable or some satellite HDTV service, you are supposed to use a HDTV with in-built HD tuner or with some exterior HD tuner to enable your HDTV process the HD signals. This is to have true HDTV experience.

HDTV materials or sources can be accessed by following ways:

1. HDTV broadcast via air or by cable
HDTV broadcasters send HD signals over the air using transmitter or via cable network. However, to process HD signals, you should have HDTV television sets which come with in-built HD tuners. While these sets are a bit expensive, HD Ready television sets, although they are cheaper, need external set-top tuner boxes to enable them to display HDTV images. In the same way, HD signals broadcast via cable require similar set-top box which is often provided by the cable operator. The QAM, as it is called, often comes with a high end plasma TV or LCD TV.

2. HDTV broadcast using satellites
Television services like Sky and Virgin Media in the UK transmit HD signals using satellites. Again, the viewers need to use satellite dish and receiver box to receive and process the HD signals.

3. HDTV Home Video materials
While most of conventional home videos are yet to be upgraded to HDTV, some of the video sources like High Definition DVD, Blu-ray are HDTV and can provide HDTV materials where HDTV broadcast is not available.

4.  Video games compatible with HDTV
As the computer games and video games are becoming the biggest market, new games like Playstation 3 and Xbox series come with HD compatibility and offer superb visual and audio experience.

Digital Television (DTV) has been replacing old analog TV world wide. Analog TV often suffer from problems like ’snow’ or ‘ghosting’ which occur when the signals are interrupted or weak. You see horizontal bars running over the screen or picture getting totally distorted. Similarly, digital TVs (DTV) that started to evolve with the onset of Standard Definition TV which uses video standards like NTSC, PAL and SECAM also had their own shortcomings as far as the picture quality is concerned.

Digital images are usually not susceptible to these problems, as the digital broadcast displays frozen image when transmission of signals is interrupted. The other advantages of DTV are better image quality, superior sound effects and their compatibility with numerous video inputs.
Again, DTVs are classified into three major types based on resolution or picture details that they are able to display.

They are as follows:
Standard Definition Televison (SDTV)
Enhanced Definition TV (EDTV)
High Definition TV (HDTV)

Standard Definition Television (SDTV)
Although SDTV provides better picture quality than standard analog television, its 480 lines of resolution is the lowest of the three types of DTVs. Definitely, they are superior to analog TV both in terms of picture and sound. However, in comparison with EDTV or HDTV, they lack some of the advanced features like wide aspect ratio and greater bandwidth.

Enhanced Definition Television (EDTV)
What distinguishes EDTV from SDTV is the progressive scan that an EDTV uses to produce display. Typically, 480p is the standard resolution of EDTV, which is also the resolution of a DVD. So, it is not necessary to mention that they are highly recommended for viewing DVDs to enjoy the best picture quality. Most low-end plasma TVs are often EDTV, as only larger, high-end plasma TVs come with HDTV compatibility. However, most LCD televisions, irrespective of screen size, come with HDTV resolution. Likewise, an EDTV can support both 4:3 aspect image and wider aspect image (16:9).

High Definition Television (HDTV)
HDTV is definitely the best of all DTVs, not only in terms of its higher resolution but also in terms of overall picture quality and its Dolby surround sound features. While 720p is its standard resolution, high end HDTVs can have higher resolutions like1080i and1080p. The true HDTV resolution (1080p) produces images of the highest resolution which is not at all possible on any other DTV. Usually HDTV signals use video compression, hence, they can store much more amount of visual data and can produce billions of natural colours.

What is ‘high definition’?

High definition or HD has been a relative term in the history of television which dates back to the beginning of second quarter of the last century. In fact, the word ‘high definition’ was coined to denote the television system which was prevalent before and during the second world war. Right from the introduction of black and white TV in 1936 till 1969 when Nippon brought out the first HD television, the word denoted one television system or the other based on the new advancements made in the technology. For instance, the NTSC which used better resolution (525 line when compared with previous 405 lines of resolution of black and white TV) and became a new standard for video formats, was considered ‘high definition’ till other advanced television system showed up. While NTSC was developed and accepted as standard in the USA, some European countries including UK established PAL, SECAM which has a standard resolution of 625 lines. The system that has the highest resolution was always described by this term.

However, France launched a black and white TV system that was supposed to be far superior to previous systems as it broadcast 819 line signals. Until 1986, it was considered to be the television system capable of broadcasting signals with the highest resolution.

Initially a few countries including Japan, the USA and some European nations, made attempts to launch analog HDTV for public use, however, except Japan, these attempts did not welcome much support in other countries. It was only after the introduction of digital TVs, modern HDTV started to make rapid advancements.

High Definition Television is finally ‘definied’
It was Nippon Hoso Kyokai who became the pioneer in the area of HDTV. He developed the first ever HDTV in 1969, however, it was only after two decades, HDTV started to replace prevalent standard definition TV. During the last seven years, HDTV included many different standards as HDTV was gaining popularity in the television market and many leading companies used the word ‘high definition’ to describe their products leading to confusion over what is true HDTV. However, the International Telecommunication Union finally accepted three HDTV standards which include 720p, 1080i and 1080p. HDTV broadcasts usually have standards set by ATSC or DVB.

High Defnition TV in today’s world

Presently, HDTV refers to HDTV display like Plasma TV or LCD TV and its accessories like HDTV tuners, antennae & satellite dish to receive HD signals. Either HDTVs may come with in-built HD tuners otherwise they require external set-top box to receive HD signals. In addition, HDTV also refers to HD video sources like Blu-ray discs, HD-DVDs and video games like Play station 3.   

High Definition Television or HDTV is a term that can be better understood when we make a comparison between different digital television standards available today. In fact, HDTV is a relative term and is often analogous with higher resolution. When we date back to the days when TV was in its formative years, there were standards like NTSC, PAL, SECAM which measured the video quality of the TV in terms of scan lines and number of frames per second lines. It was in mid forties of last century , NTSC or National Television System Committee which universalized a video standard which had  4:3 aspect ratio and 525 scan lines refreshing at a rate of 30 interlaced frames, or 60 fields per second. A few nations like the UK, did not stick to this standard and made a change in refresh rate, thus UK followed TV standard based on 50 Hz instead of 60 HZ which was set as standard in countries like the US and Canada. However, PAL and SECAM which came as alternatives for NTSC had more scan lines (625 instead of 525 lines) to provide more detailed pictures on the screen. Although the pictures were better on PAL but the refresh rate tend to be slower resulting in flicker which used to annoy the viewers.

The real revolution took place in 1982, when ATSC or Advanced Television Systems Committee was formed to develop a new television technology that can altogether replace the analogue video formats like NTSC, PAL or SECAM. First began as technological advancement in analog television, ATSC soon started to develop digital TVs that include standard TV, enhanced TV and finally High-definition TV. All these DTVs promised better picture quality in terms of resolution, refresh rate, colour quality etc. Another advantage that DTVs holds over previous analog televisions was improved sound quality that comes with their impressive display.

All the Digital TVs that include LCD television or plasma TV differ depending up on how many pixels per inch make up the image (this is called resolution), number of scan lines over the screen (both vertically and horizontally) and the aspect ratio. The aspect ratio shows how wide is the screen in relation to its height. In early televisions (analog) and standard digital televisions the 4:3 is the aspect ratio is still followed which means the width will be slightly longer than the height of the screen. This aspect ratio is much closer to 16 mm or 35 mm movie, and was popular until the wider format of movies (70 mm) started to be used by most movie makers during the last two decades. The 16:9 or wider aspect ratio started to be followed by television makers to present movie like viewing experience and soon became the standard for the HDTVs.

Resolution is one of the major characteristics that help us to distinguish one TV from another. Compared with old analog televisions, present HDTVs can show ten times higher resolution or even twenty times! A high end HDTV LCD TV (which is 1980p resolution), can show more than 4 million pixels on its screen presenting imagers so sharper and more detailed. When resolution is taken into account, any digital TV that can show minimum resolution of 720p is HDTV. There are HDTV resolutions like 720p, 1080i, 1080p etc. While there is not much to compare between 720p and 1080i as they look more or less alike, however, 1080p images always look superior to any other HDTV resolution. Again, 720p and 1080p indicate the method of scanning is progressive scan which tends to present better image quality against the same resolution scanned by interlace method ( which is denoted by ‘i’ and which follows the resolution). 

Digital TVs also come with improved audio quality as they adopt new audio systems like Dolby Digital which minimize the unwanted noises and also use much more audio data on their tracks. Dolby uses five channels to provide surround sound quality which is more or less similar to what one experiences in a cinema hall. However, most of the HDTVs usually feature only two channels and only a few can support 5.1 channel feature of full Dolby Digital.