Display Resolutions
Confused by terms like 720p and 1080i, don't know your Standard Definition from High Definition? Despite the plethora of technical terms, understanding the difference between all the screen resolutions need not be that hard. Check out our guide below to get the low down on what it all means for you.
Overview
Common Display Resolutions
Standard Definition (SD), Enhanced Definition
(ED), and High Definition (HD)
480i - Standard Definition
480p - Enhanced Definition
576i - Standard Definition
576p - Enhanced Definition
720p - High Definition
1080i - High Definition
1080p - High Definition
Overview
Display resolutions can be confusing, and it is important to remember that the resolution of CRT TV's are measured in a different way from flat panel and projection displays. When referring to a flat-panel, fixed pixel array displays like Plasmas, LCD's, and rear projectors using DLP or LCD technologies, display resolution simply means the physical number of dots or pixels in each row and column that make up the entire screen. For example a 640x480 pixel display can display 640 pixels on each of 480 horizontal lines - with a total display of over 300,000 pixels. Generally, the more pixels the display has the better the picture. Whereas in CRT TV sets, the horizontal lines that make up the picture are not divided into pixels, and the total resolution of the image is described as the number of lines being displayed, or scan lines.
You will see flat panel and projection displays marked with the a resolution value followed by the letter 'i' or 'p', e.g. 1080i or 1080p. Both these values represent the same number of horizontal picture lines (1,080) while the 'i' stands for interlaced and the 'p' stands for progressive (also referred to as Progressive Scan). So, what do these mean?
- Interlaced displays draw every other interlaced picture line, and then go back and draw the remaining lines. In other words, it draws lines 1, 3, 5, 7... and then after completing all odd numbered lines, it goes back to draw lines 2, 4, 6, 8... Every other horizontal line alternates between an on and off state. For a TV operating at 60 Hz or 60 cycles per second, every odd numbered horizontal line is redrawn 30 times a second, and every even numbered line is redrawn 30 times a second. This alternating format can appear to shimmer when compared to a progressive TV of the same frequency - particularly in the presence of UV lights, who's own frequency can amplify the flickering effect. For most of us, the effect isn't obvious until we see it compared with a progressive scan image.
- Progressive displays, on the other hand, draw the all horizontal lines in order, so that at 60 Hz, every horizontal lines is 'drawn' 60 times per second. In other words, it draws lines 1, 2, 3, 4, 5... in every cycle. As a result, the display appears sharper than an equivalent interlaced display.
It is worth remembering that a progressive capable display will revert to interlaced format if the input signal is interlaced. Keep this in mind when purchasing a external devices such as a DVD player or set top box, as generally only those with a component, DVI, or HDMI outputs support progressive scan.
Common Display Resolutions
Standard Definition (SD), Enhanced Definition (ED), and High Definition (HD)
The terms Standard Definition (SD), Enhanced Definition (ED), and High Definition (HD) are a way of grouping various TV resolutions together, so that you know what you're dealing with.
- Standard Definition TV signals have either 480 (480i) or 576 (576i) interlaced horizontal lines making up their picture.
- Enhanced Definition TV signals have either 480 (480p) or 576 (576p) progressive horizontal lines making up their picture.
- High Definition TV signals have either 720 progressive (720p) horizontal lines, or 1,080 interlaced (1080i) or progressive (1080p) horizontal lines making up their picture.
There is currently debate within the audio/visual community on whether 720p or 1080i resolutions produce a higher quality image. 1080i has more lines of resolution, but is an interlaced format so it cannot display progressive-scan DVDs (unlike 720p and 1080p displays) without having to revert to interlaced display. By contrast 720p is the most common HDTV broadcast format, and according to some is better at displaying movement due to its progressive display. The important thing to remember is that the difference is largely a matter of opinion, and both 720p and 1080i will look better than a Standard Definition or Enhanced Definition (i.e. non-HDTV) display.
| Designation | Usage examples | Definition (Number of Horizontal Lines) |
Refresh Rate (Hz) | |
|---|---|---|---|---|
| Interlaced | Progressive | |||
| Low Definition | LDTV, VCD | 240; 288 (SIF) | 24, 30; 25 | |
| Standard Definition | SDTV, SVCD, DVD | 480 (NTSC, PAL-M) | 60 | 24, 30 |
| 576 (PAL, SECAM) | 50 | 25 | ||
| Enhanced Definition | EDTV | 480; 576 | 60; 50 | |
| High Definition | HDTV, HD DVD, Blu-ray | 720 | 24, 25, 30, 50, 60 | |
| 1080 | 50, 60 | 24, 25, 30 | ||
480i - Standard Definition
480i is a form of standard definition television and can be transported by all major digital television formats, ATSC, DVB and ISDB, but is most commonly found in countries that use NTSC, i.e. United States, Canada, Japan, and South Korea. 480i has the same resolution as an NTSC analog signal, i.e. 480 interlaced horizontal lines making up the picture. Each horizontal line is composed of 704 or 720 pixels (depending on the implementation), but the viewable area is smaller, with only 640x480 pixels visible (307,200 pixels). 480i supports both a 4:3 and 16:6 widescreen aspect ratio.
480p - Enhanced Definition
The common resolution found on NTSC DVD's. 480p is a form of enhanced definition television and can be transported by all major digital television formats, ATSC, DVB and ISDB, but is most commonly found in countries that use NTSC. 480p has the same resolution as an NTSC analog signal, i.e. 480 progressive horizontal lines making up the picture. Each horizontal line is composed of 704 or 720 pixels (depending on the implementation) but the viewable area is smaller, with only 640x480 pixels visible (307,200 pixels). 480p supports both a 4:3 and 16:6 widescreen aspect ratio.
576i - Standard Definition
576i is a form of standard definition television and can be transported by all major digital television formats, ATSC, DVB and ISDB, but is most commonly found in countries that use PAL. 576i has the same resolution as a PAL analog signal, i.e. 576 interlaced horizontal lines making up the picture. Each horizontal line is composed of 704 or 720 pixels (depending on the implementation) giving a resolution of 704x576 (405,504 pixels) or 720x576 (414,720 pixels). 576i supports both a 4:3 and 16:6 widescreen aspect ratio.
576p - Enhanced definition
The resolution commonly found on PAL DVD's. 576p comes in two forms. 576p at 25 Hz is a form of standard definition television, while 576p at 50 Hz is a form of enhanced definition television. 576p can be transported by all major digital television formats, ATSC, DVB and ISDB, but is most commonly found in countries that use PAL. 576p has the same number of horizontal lines (576) making up the picture as a PAL analog signal or a 576i digital signal, but due to its progressive format it has superior picture quality. Each horizontal line is composed of 704 or 720 pixels (depending on the implementation) giving a resolution of 704x576 (405,504 pixels) or 720x576 (414,720 pixels). 576p supports both a 4:3 and 16:6 widescreen aspect ratio. 576p is the common resolution found on PAL DVD's.
720p - High Definition
720p is a high-definition television format, and can be transported by all major digital television formats, ATSC, DVB and ISDB. The image is composed of 720 horizontal lines, i.e. 720 progressive horizontal lines making up the picture. Each horizontal line is composed of 1280 pixels giving a resolution of 1280x720 (921,600 pixels). There is no interlaced equivalent of 720p.
| TV Standard | Resolution | Aspect Ratio |
|---|---|---|
| SECAM | 350 x 576 lines |  |
| PAL, | 350 x 576 lines | |
| PALPlus | 350 x 576 lines |  |
| NTSC | 270 x 480 lines | |
| Laserdisc | 560 x 480 lines (NTSC), 560 x 576 lines (PAL) | |
| VHS | 240 x 480 lines (NTSC), 240 x 576 lines (PAL) | |
| S-VHS | 400 x 480 lines (NTSC), 400 x 576 lines (PAL) | |
| VCD | 352 x 240 lines (NTSC), 352 x 288 lines (PAL) | |
| SVCD | 480 x 480 lines (NTSC), 480 x 576 lines (PAL) | |
| EDTV 480p | 640 x 480, 704 x 480, or 852 x 480 lines | or |
| DVD | 704 x 480 lines (NTSC), 704 x 576 (PAL) | or |
| HDTV 720p | 1280 x 720 lines | |
| HDTV 1080i | 1920 x 1080 lines | |
| HDTV 1080p | 1920 x 1080 lines | |
1080i - High Definition
1080i is a high-definition television format, and can be transported by all major digital television formats, ATSC, DVB and ISDB. The image is composed of 1080 horizontal lines, i.e. 1080 interlaced horizontal lines making up the picture. Each horizontal line is composed of 1920 pixels giving a resolution of 1920x1080 (2,073,600 pixels) - which is 2.25 times that of 720p.
1080p - High Definition
1080p is a high-definition
television format, and can be transported by all major digital television
formats, ATSC,
DVB and ISDB. The image is composed
of 1080 horizontal lines, i.e. 1080 progressive
horizontal lines making up the picture. Each horizontal line is composed of
1920 pixels giving a resolution of 1920x1080, or 2,073,600 pixels - which is
2.25 times that of 720p. 1080p is the highest resolution available for
broadcast, but due to the large amount of
bandwidth consumed by a 1080p signal, it is rare to find a TV channel
broadcasting in this format. Generally, 1080p content is only found in
pre-packaged media, such as HD DVD and
Blu-ray discs.