Big is beautiful when it comes to television pictures, but thin is still in when it comes to the actual television.
Thus the boom in LCD televisions that are less than 10mm thick. They still have "LED backlight" written on the box, so people assume that it's the best picture quality they'll get from an LCD. Perhaps not.
Edge-lit vs Matrix-lit LED
Many television manufacturers create ultra-thin LCD televisions by putting the LED backlight at the sides of the display rather than behind it, a technology know as "Edge-lit" LED backlighting. On their thicker LCD televisions they're starting to use "Matrix-lit" LED screens (also known as "local dimming LED").
This means that the LED lights are behind the display rather than along the side. More importantly, it means the LED backlight is divided into segments that can be controlled separately when it comes to brightness.
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| Samsung employs Edge-lit LCDs in some of its TVs |
How Matrix-lit screens provide better contrast
Vampire shows seem to be all the rage at the moment, so lets use them as an example. If there's a midnight graveyard dark with a bright full moon in the top left corner of the picture, a Matrix-lit LED screen can boost the backlight behind the moon but dim the backlight across the rest of the panel.
This offers a much better contrast by ensuring the moon is bright but the shadows remain black with high contrast so you can still see the vampires lurking in wait.
The Edge-lit compromise
Meanwhile an Edge-lit LED can only dim the backlight uniformly across the display, so it needs to make a decision as to whether it wants to be brighter to make the moon look good, or darker to make the shadows look good.
It will probably compromise, meaning your vampires are lost in the shadows and the full moon isn't as vivid as it could be.
Don't be a sucker. If you're more concerned about picture quality than fashion, stop to ask whether that wafer-thin LCD television is using Edge or Matrix-let LED backlights.
Buying a flat screen TV? Have a question you'd like us to answer? Add your comments or questions about flat screen TV issues to the discussion below.
Also in this series, How to Pick a Great Flat Screen TV, And Not Get Sucked In By Marketing Hype:
Part 15: How big a TV is too big?
Part 14: Should I care about refresh rates?
Part 13: How do I compare HDTVs in the store?
Part 12: Hiding your television
Part 11: calibrating your television
Part 10: those pesky upscaling issues explained
Part 9: video inputs and future proofing
Part 8: Logitech Harmony vs AV Link remote controls
Part 7: Should you upgrade your TV for DLNA?
Part 6: TV tuners and "Digital Capable"
Part 5: HDMI and component ports
Part 4: LED and backlighting
Part 3: Screen size
Part 2: Refresh rates
Part 1: Brightness and contrast ratios
Also see our 5 tips for buying a digital TV set top box
And also see the lowdown on Freeview, and whether you should care
If you're new to Digital TV, or have yet to make the leap, start by reading Prepare yourself for Digital TV