A comparison of TV, HDTV and computer monitors

The phrase "high definition" has been used to describe many forms of TV, the best way to understand is to compare TVs you may have seen.

^{Published on 21st April 2007 at 12:03 by Brian Butterworth on UK Free TV}

You may be confused by the phrase "high definition" because it has been used in the past to describe many forms of TV, and has several meaning even today. The best way to understand is to compare the many forms of TV and computer monitors you may have seen.

The following section compares various formats, where the total number of pixels (picture cells, or the dots that make up a digital picture) is compared to a standard analogue TV picture

UK, 405-line black and white TV to 1950

414x377, 5:4, 0.14 megapixels, 37.63%
pixel shape: 1:1.13 

Before the 1950s, the shape of televisions was 5:4, and the single BBC Television Service was broadcast. The picture was monochrome and the resolution was less than a third of the standard TV resolution today.

UK, 405-line black and white TV, 1950-82

414x377, 4:3, 0.14 megapixels, 37.63%
pixel shape: 1:1.21

From 1950, the shape of televisions changed to the familiar 4:3 shape, but the resolution was not changed. This was used for both BBC1 and the new Independent Television stations.

UK TV, (ITV/C4 digital), centre cut out

405x576, 4:3, 0.22 megapixels, 56.25%
pixel shape: 1:1.89

If you use a digital receiver (Freeview, Sky, cable) to watch a ITV or Channel 4 16:9 transmission in a "centre cut out" on a 4:3 television, you will be only using 56% of the TV screen.

UK, digital TV, deep 16:9 letterbox on 4:3 TV

720x405, 16:9, 0.27 megapixels, 70.31%
pixel shape: 1:1

If you use a digital receiver (Freeview, Sky, cable) to watch a 16:9 transmission in a "deep letterbox" on a 4:3 television, you will be only using 70% of the TV screen.

VGA, 1980s computer monitor

640x480, 4:3, 0.29 megapixels, 74.07%
pixel shape: 1:1

An old-fashioned VGA computer monitor (or a current high-specification PDA) resolution has about three quarters of a standard TV.

UK TV, (ITV/C4 digital), fullscreen 4:3

540x576, 4:3, 0.29 megapixels, 75%
pixel shape: 1:1.42

To provide more channels on Freeview, ITV and Channel 4 used this special mode to transmit their programmes. This reduces the resolution to 75% of a standard TV.

UK TV, (ITV/C4 digital), fullscreen 16:9

540x576, 16:9, 0.29 megapixels, 75%
pixel shape: 1:1.89

On Freeview, ITV and Channel 4 used the special mode for 16:9 transmissions too, which again reduces the resolution to 75% of a standard TV.

UK digital TV, centre cut out on 4:3 TV

540x576, 4:3, 0.29 megapixels, 75%
pixel shape: 1:1.42

If you use the "centre cutout" option to watch a 16:9 digital transmission on a 4:3 TV, the resolution is also 75% of a standard TV.

UK digital TV, 14:9 letterbox on 4:3 TV

630x504, 14:9, 0.30 megapixels, 76.56%
pixel shape: 1:1.24

This is quite a common mode, as it used to watch 16:9 transmissions on 4:3 TVs using digital set-top boxes, used by analogue TV and also by some digital TV channels (such as UKTV History).

UK TV, 4:3 on 4:3

720x576, 4:3, 0.39 megapixels, 100%
pixel shape: 1:1.06

This is the best resolution you can get from digital TV when watching on a 4:3 TV using 4:3 material.

UK TV, 16:9 on 16:9

720x576, 16:9, 0.39 megapixels, 100%
pixel shape: 1:1.42

This is the 'designated' mode for UK digital television, where you can view the whole picture on a widescreen digital TV. This is the mode that most DVD use also.

SVGA

800x600, 4:3, 0.45 megapixels, 115.7%
pixel shape: 1:1

This is the resolution obtained by most 1990s computer monitors.

XGA

1024x768, 4:3, 0.75 megapixels, 189.6%
pixel shape: 1:1

This is the resolution obtained by recent computer monitors.

HDTV 720-line

1280x720, 16:9, 0.87 megapixels, 222.2%
pixel shape: 1:1

The 'standard' HDTV 720-line resolution has slightly more than twice the resolution of a standard TV.

HDTV 1080-line

1920x1080, 16:9, 1.97 megapixels, 500%
pixel shape: 1:1

The 'best' HDTV 1080-line resolution has five times the resolution of a standard TV.

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