LED, LCD and plasma TV: Compare features & prices LG 47LM670 review http://www.which.co.uk/technology/tv-and-dvd/reviews/led--lcd-and-plasma-tv/lg-47lm670/review/

Test programme
We change and improve our testing and scoring procedure on an annual basis, so TVs tested in different years may not be directly comparable

Type of TV
LCD and LED TVs differ only in the way the screen is illuminated. A handful of backlight lamps light-up a traditional LCD display, on 'LED TVs' the lamps have been replaced by hundreds of smaller LEDs (light emitting diodes). LEDs are also more energy efficient than traditional bulbs. Plasma TVs do not have backlights but illuminated by the brightness of individual gas cells.

Digital tuner
The type of built-in digital tuner. Dual HD tuners have both Freeview HD and Freesat HD - but the tuners operate seperately, not in conjunction. So for instance, you can't watch one channel on Freesat and record another on Freeview.

3D TV
The TV is capable of displaying 3D broadcasts from Sky or Virgin and 3D Blu-ray movies. 3D glasses are sometimes sold separately

3D type
Active shutter technology provides Full HD 1080p video to each eye when you are watching 3D content, though you need to wear active shutter glasses, which can be bulky, expensive (£50-£100) and may not always come packaged with the TV. Passive 3D requires cheap polarising glasses (typically costing £1-£4), though you do not always get such detailed and immersive 3D visuals.

Screen size (inches)
This is the size of the screen in inches, measured diagonally across.

HD ready 1080p
All the full-size TVs we review are 'HD-ready' and suitable for watching 1080i HDTV broadcasts via Sky, Virgin or Freesat. The 'HD-ready 1080p' logo means the TV has a 1,080 line screen resolution, and can process a 1080p/24 signal used on Blu-ray DVD movies - although this is not a guarantee of the best HD picture. Older 'HD-ready' sets will switch to a 1080i picture when used with high-definition DVD, but are more likely to suffer from a slight picture judder on panning shots.

Native resolution (pixels)
The number of pixels the TV can display (horizontal x vertical)

Smart TV
Allows you to access a selection of internet 'apps' - micro sites of web content such as video catch-up and movie download services. Some internet TVs allow full web browsing.

PVR
Allows you to plug a HDD drive into the USB port to pause, rewind and record live TV. Some models feature a built-in PVR.

HDMI
Socket for connecting to high-definition equipment, such as Blu-ray player or Sky HD box. Carries HD video and multi-channel audio.

Independent picture settings
Allows you to set and save different picture settings for different inputs (for instance Scart and HDMI) on your TV. Useful if you've fine tuned your picture to different settings, for watching DVDs or a Sky HD box, for example.

USB port
Means you can plug in your digital camera and view photos on the big screen (they tend to look great on high resolution displays). Many USB ports support digital music and camcorder playback.

SD card slot
Means you can view photos from various digital camera memory cards on the big screen. High resolution digital photos viewed this way usually look very good.

Headphone output
Socket for plugging in headphones.

Headphone volume control
The most versatile headphone outputs allow you to control headphone volume independently from the main speakers. Useful if you're hard of hearing.

Audio description
This means the TV can decode an audio description signal. AD is an additional narration for visually-impaired people that describes significant visual information, such as body language and scenery.

Voice zoom
Boosts dialogue over background noise and music

App store
Access to online app store letting you download more apps - micro sites showcasing some of the best bits of the web.

Pre-loaded apps
Smart TVs come with a number of pr-loaded apps. Manufacturers can add to these at any time - this is the number at the time of testing

Web surfing
Allows you to surf the world wide web via your TV

Wi-fi
Some Smart TVs come with built-in Wi-Fi, but most connect wirelessly with the addition of a wifi USB dongle (sold seperately).

Switched-on (Watts)
Based on using our viewing panel's ideal picture settings. Settings are aimed at getting the best picture, but typically mean it uses less energy too. An energy efficient 40-inch LED should use around 60-70 watts. Larger 42-inch plasma TVs will use more than twice that amount of energy.

Eco mode (Watts)
Energy consumed with energy saving picture setting activated (typically involves dimming the backlight).

Light sensor (Watts)
Energy used by sensor with the lights dimmed (1 lux). If selected the light-sensor automatically adjust the brightness of the picture according to how light or dark the room is. Viewing in darker rooms with the light sensor switched on can dramatically reduce energy consumption.

Standby (Watts)
During standby after 2 hours and/or using ECO mode. Ideally this should be below 2 watts to meet the Energy Saving Trust recommendation

Off button
Mechanical 'hard off' buttons turn the TV off completely. Electronic 'soft off' buttons need some power to switch the set back on.

Brightness
Ideal brightness setting as used by our expert viewing panel in a dimly-lit room. Settings may vary slightly from sample to sample.

Contrast
Ideal contrast setting as used by our expert viewing panel in a dimly-lit room. Settings may vary slightly from sample to sample.

Colour
Ideal colour setting as used by our expert viewing panel in a dimly-lit room. Settings may vary slightly from sample to sample.

Picture profile
Ideal picture profile setting as used by our expert viewing panel in a dimly-lit room. Settings may vary slightly from sample to sample.

Sharpness
Ideal sharpness setting as used by our expert viewing panel in a dimly-lit room. Settings may vary slightly from sample to sample.

Backlight
Backlightsetting as used by our expert viewing panel in a dimly-lit room. Settings may vary slightly from sample to sample.

Other settings
Other settings as used by our expert viewing panel in a dimly-lit room. Settings may vary slightly from sample to sample.

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