Image Makers - LED vs Plasma

If a TV can't present a great image, then it's not smart at all.

All this Smart TV technology is great, but let's go back to basics for a minute: what is the most fundamental aspect of a television? It's the picture, of course, and whether you're looking to buy an LED or plasma TV, the technology that goes towards producing excellent image quality is an extremely complex animal and forever advancing in the relentless pursuit of pixel perfection.

So what makes a good picture?

The key attributes of a great image include resolution, response time, colour accuracy, contrast and brightness and how well the pictorial information from the signal source is received, interpreted, relayed and controlled. That video processing is a hugely significant factor and is often the greatest determinant of the quality of the finished product.

Low contrast ratio levels are no longer a point of weakness in plasma or LED* televisions, with 'millions- to-one' ratings now common, but the ability to accurately control contrast is essential. Advancements in controlling how contrast is altered now means that the best TVs can now adjust contrast of the panel in separate blocks, rather than apply a blanket change to the entire screen at once. The result is a better colour range on screen, with darker blacks and more vibrant colours.

Remember that deep inky blacks are an important measure of picture quality, because without them it's hard to make colours and whites stand out. The ability to produce true black also allows a TV to reproduce exceptional detail within dark scenes.

LED picture

Popular thought is that LED televisions perform strongly in rooms with high ambient light, producing incredibly lifelike, bright and vivid pictures. As the focus of most of the recent innovations in display technology, they also typically provide the latest features, the slimmest form-factors and, in most cases, the best pictures too.

Until recently, the principal challenge for these TVs has been achieving true black. Formerly lit by 'always-on' fluorescent light tubes, they suffered from being overly bright with everything, as subtle adjustments to the way the panel was lit were impossible. The introduction of LEDs as a backlight system improved this, and now with edge-lit LEDs (where the lights are located around the perimeter of the screen, rather than behind it) blacks have never been better.

What's more, these LED lights can be more easily and discreetly controlled. With the ability to be turned on and off with greater precision, the result is deep, rich blacks and better overall colour accuracy. Samsung advances this with 'Micro Dimming,' a technology that uses a renewed chipset and an enhanced algorithm for incredibly precise control of the lighting to take picture clarity to new heights.

Edge-lit LED lighting has done more than anything to boost performance, and similar advances in refresh rate, coupled with better video processing, have also tackled the problem of 'motion blur.'

How quickly the pixels respond – measured as going from black to white to black again – and refresh rate (how often the whole image is replaced on the screen) can determine how well the panel handles fast-moving images. Motion blur, which is evident as 'light trails' or blurring on the ball when watching something like tennis or footy, is common to LED TVs with slower refresh rates and response times.

With Smart LED televisions, refresh rates have soared, response rates been reduced and, equally importantly, a more holistic approach to assessing and addressing the resolution of a moving image has been adopted. Samsung, again, has been pioneering in this respect, producing the 'CMR' (Clear Motion Rate) measurement that is the product of panel, lighting unit and chipset working together, where the higher the number, the sharper and crisper are the moving images.

Plasma picture

Plasma technology is generally accepted as being more suited to a darker environment, with good colour accuracy and the ability to render total blacks making for clear and nicely detailed images. Additionally, an almost instantaneous pixel 'response time' minimises motion blur in fast-moving sequences like sports or action films, and a near-180 degree viewing angle makes viewer positioning irrelevant.

With plasma TVs, the issue of reflection from the outer glass layer can now be entirely removed – quite literally – by doing away with the clear glass filter in front of the panel, significantly reducing the chances of glare and improving brightness. Enhancing this effect, the inclusion of 'real black filter' technology, which increases light levels emitted from the plasma cells while reducing the brightness lost through diffusion of that light, heightens contrast by producing deeper blacks and brighter whites. The result is that plasma is now a more than suitable choice for bright rooms.

Displaying any fast-moving vision on a huge screen is challenging for any TV technology. For plasma, given that response rate is not an issue, attention shifts to what is known as 'subfield motion' technology. A 'subfied' is where the same image is repeated in order to help eliminate 'phosphor lag,' which is evident as a type of colour artefacting caused by the individual cells in the plasma grid switching on and off. In most plasma TVs, this is done eight times a frame, and this is the equivalent to a 400Hz subfield frequency. Samsung plasma TVs have a 600Hz subfield frequency, which ups this to 12 times a frame for broadcast TV and DVD sources, and 25 times for Blu-ray. The benefit of updating the fields more frequently is realised in smoother images and the virtual elimination of motion judder.

Looks pretty, is pretty

Design has an important part to play in delivering the very best viewing experience, and, with major international design awards from CES, EISA, IF, and IDEA since 2006, Samsung has considerable cred in this area. And in this year alone, Samsung as already received 37 innovation awards, all from the 2011 Consumer Electronics Show.

The 'One Design' concept in the Samsung LED range merges panel and bezel to create a near-borderless viewing experience, making the picture appear to merge with its surroundings. The bezel is just 5mm thin, or less than a fifth the width of those on conventional televisions. It's a barely-there bezel!

The Samsung 'Plasma+1' concept means that every plasma TV in the range has had the display area increased by one inch – last year's 63 inch panel becomes 64 inch, for instance, but the physical dimensions of the panel is the same. To boot, the width of some plasma models is up to 50 percent slimmer than last year's!

Samsung's LED and plasma televisions are now also home to a suite of energy efficiency measures, including sensors that work to reduce your power consumption by automatically altering the brightness level of the image depending on the intensity of light in the room.

Fancy on the inside

As you can see, producing an excellent picture is a complex endeavour and not easily achieved. The video processing expertise that goes into making a great TV is a specialised and highly skilled enterprise that really sorts the men out from the boys. But you can appreciate that, as with most things in life, the best technology is generally the technology worth having.