LED, LCD and plasma TV: Buying a new TV HDTV features guide
Modern HD TVs are awash with logos and features. Click on any of the six key features below and let our interactive guide navigate you through the jargon – from choosing between LCD, LED and plasma to finding out more about 3D TV and the latest energy-saving features.
Once you’ve decided which features are important to you, visit our HDTV reviews and pick out the model that's right for you.
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| LCD features explained | |
|---|---|
| Features | Explanation |
| Display | |
| Screen resolution | This is the number of pixels or lines displayed on the TV screen. Expressed as width x height, the highest screen resolution commonly available is 1920x1080. This is desirable for high-definition material, but it doesn't necessarily mean you'll get the best pictures for watching normal TV broadcasts or DVDs. A good LCD or plasma TV often relies far more on decent digital processing software. |
| Contrast | The difference between how dark and light the LCD or plasma TV will go. A high contrast ratio should mean deeper blacks and whiter whites, with a good range of subtle colour gradients in between. However, it's difficult to compare claims from one brand to the next because of the variety of measuring methods used. And higher numbers do not necessarily mean better TV pictures. Contrast ratio is not a linear value so 12,000:1 is not 'twice as good' as 6,000:1. |
| LCD and plasma | Liquid crystal display (LCD) TV screens come to life when a backlight is shone through the screen's matrix of tiny coloured liquid crystal cells. Digital signals control each cell, letting varying amounts of colour through, building up a picture. A plasma TV display is an array of tiny gas cells sandwiched between two sheets of glass. Each cell acts like a mini fluorescent tube, emitting ultraviolet light which then strikes red, green and blue spots on the screen to build a picture. LCD TVs use far less power than plasmas, but plasma TVs have traditionally sported deeper, richer blacks and better viewing angles. However, LCD technology has improved and it's the quality of the digital processing software, not the technology per se, that will more often than not dictate the quality of the picture. |
| Widescreen | The vast majority of LCD and plasma TVs are widescreen – with an aspect ratio of 16:9 (width x height). However, many small LCD displays are not true widescreen models and can slightly stretch or squash the picture to fit the screen. Typical sizes include computer monitor standards 16:10 and 14:9, or even the old 4:3 box shape. Digital TV is broadcast in a widescreen format. |
| High-definition TV | |
| HD TV | HD TV boasts roughly double the resolution of a standard-definition signal, making it more detailed and realistic. It's available on Sky or Virgin for a monthly fee, or free on Freesat. Freeview HD channels will be available in 2010. To watch you'll also need an 'HD-ready' LCD or plasma TV. Not everything on the dedicated HD channels is actually recorded in HD but more programmes are being recorded in HD all the time. |
| 1080i | There are two main types of HD picture – 1080i and 1080p. HD TV is broadcast in the 1080i picture format by Sky, Virgin and Freesat. The four-digit number tells you how many horizontal lines make up the picture (standard-definition is made up of 576). The 'i' stands for interlaced, meaning the lines are scanned not one after another, but by every second line to create a field. A field of odd lines and a field of even lines are combined to make a frame, scanned at 25fps (frames per second). |
| 1080p | There are two main types of HD picture – 1080i and 1080p. High-definition Blu-ray discs are recorded in 1080p. The 1,080 horizontal lines are scanned progressively, or one after another, making the 1080p image marginally more detailed and realistic than a 1080i image, but the difference is really quite subtle. 1080p is not broadcast because the pictures would simply take up too much space, or bandwidth. |
| Screen sizes | |
| 15 - 23 inch | Smaller LCD TVs are ideal as a second set for the kitchen or bedroom, but be wary of using smaller sets to watch high-definition material. Sub 26-inch screens will generally not do justice to the extra detail of HD TV. Sound quality also has a link to the size of the screen. Bigger displays can house larger speakers, which will tend to give a better audio performance. |
| 26 - 32 inch | For the average living room 32-inch LCD TVs will suffice. 32-inch is the most popular screen size and more akin to the display of a typical conventional CRT. We tend to find 32-inch sets the best size compromise for watching in both standard and high-definition and our Best Buy 32-inch Panasonic TVs currently deliver the best all-round picture quality we've seen. If you favour watching HD TV above anything else – then opt for a bigger screen. |
| 37 - 50 inch | Huge screens do justice to the extra detail of high-definition pictures, but may not be the wisest choice if you just want to tune into regular standard-definition Freeview broadcasts. They tend to be less forgiving to the digital processing side effects more apparent on standard-definition, especially if you sit too close. Sitting 2.8 metres from the TV has traditionally been considered the ideal viewing distance, but the bigger the screen the further away you should sit. |
| Logos | |
| 15 - 23 inch | The HD-ready label means the TV meets the minimum criteria for displaying 1080i HD TV signals – so the TV is ideal for watching HD TV from Sky, Virgin or Freesat. Most new HD-ready television sets will also process the 1080p HD signal – the marginally more detailed HD format recorded on Blu-ray discs. If the TV does not support 1080p, it simply switches to 1080i. Virtually all LCD and plasma TVs are at the very least HD-ready. |
| HD-ready 1080p | The LCD or plasma TV can process a 1080p signal and has a high screen resolution of 1080 horizontal lines (1920x1080). In theory, this should mean even better HD pictures. In practice the quality of the TV picture has more to do with the picture processing software, than just the screen resolution. Similar-sounding and looking logos such as, HD Full, 1080HD or 1080HD-ready are also commonplace, but exact meanings differ between manufacturers. |
| 100Hz and 200Hz | Most TV pictures are broadcast or recorded at 50Hz – that's 25 frames per second. In an attempt to reduce motion blur, many LCD and plasma TVs feature 100Hz processing software. This basically doubles the number of frames on screen per second. The very latest LCD and plasma TVs boast 200Hz processing software, quadrupling the original frame rate, and placing 100 frames on the screen every second. |
| Digital processing software | Many of the fancy-sounding labels you'll see on these TVs refer to the digital-processing software, or engines, used by LCD and plasma televisions. For instance, Samsung, uses its Digital Natural Image engine (DNle), LG its Dual XD or simply XD engine, Panasonic uses Vreal2 and Philips either Pixel Plus HD, Perfect Pixel HD or simply Pixel Plus. Decent processing software usually equals good pictures. For instance, many Sony LCD TVs feature the Bravia2 processing engine – most sport good pictures. |
| Sockets | |
| Scart inputs | HDMI sockets are designed for connecting high-definition equipment such as Blu-ray players. Connecting standard DVD players with HDMI will rarely improve the picture. Most HDMI sockets support a Consumer Electronics Control (CEC) feature. This allows you to control other CEC-enabled AV equipment connected together by HDMI, via just one remote control. Different brands give CEC different names, including Anynet+ (Samsung), Bravia Sync (Sony), Kuro Link (Pioneer), Simplink (LG) and Viera Link (Panasonic). |
| Audio outputs | Red and white phono sockets allow you to connect your LCD or plasma TV to a stereo amplifier – for improved hi-fi sound. Digital coaxial (wire) and optical (fibre optic) carry both stereo or surround sound signals. Make sure your surround-sound system input matches the output on your LCD or plasma television. Many TVs feature virtual surround sound: they mimic the effect using the two main speakers, but this is usually disappointing. |
| Memory card slots and USB ports | Many LCD and plasma TVs are equipped with memory card slots that let you plug the card from your digital camera directly into the TV. More common are USB ports for connecting memory sticks or digital equipment. Either way, the picture quality is typically excellent and many manufacturers, such as Sony, design their TVs to look like picture frames. As an added bonus, the USB option sometimes allows playback of MP3 music files or digital video files. |
| Green features | |
| Eco modes | Many new LCD and plasma TVs have eco or energy-saving settings. Occasionally, this can be slightly misleading and may refer only to an option to switch off the front panel LED – making a negligible power saving. Some television manufacturers have also taken to adding a quick-start standby mode. This allows the TV set to be turned on marginally quicker than from regular standby, but often uses considerably more power. Some energy-saving modes can simply involve switching the wasteful quick-start option off. |
| Ambient light sensor | If selected, an ambient light sensor will automatically adjust the brightness of the LCD TV's backlight, according to how dark or light the room is. In dark conditions, the most efficient sensors can dramatically reduce power consumption – slashing a typical 100-watt reading for a 32-inch TV screen in half. Plasma TVs do not feature backlights but can still have ambient light sensors. The sensor automatically adjusts the brightness of each gas cell that makes up a plasma display picture. |
| Radio blanking | Some LCD and plasma TVs can blank the screen when tuned to a digital radio channel. It's still not quite as green as listening via a typical tabletop DAB radio, but can significantly reduce energy use. For larger TVs, radio blanking can slash more than 100 watts off the total power used. On smaller television sets the effect is less dramatic. Sony, Sharp and Pioneer TVs usually include a screen-blanking feature. |
| On/off switches | Many new TVs have 'soft' on/off switches rather than traditional mechanical buttons. These have the advantage of being less prone to breaking. However, the 'soft' switch requires an electrical current to turn the set back on – meaning many LCD and plasma TVs use power even when they are switched off. The power used is low (less than 1 watt), but if you truly want to switch your TV set off, the only choice may be to switch it off at the mains. |