LCD TVs are now in vogue in India. Everybody desires one and even middle class families have started to buy them to replace their old CRT TVs. However the biggest challenge that is being faced by the buyers, is the selection of the right make-model. Hundreds of models are on display, but not enough technical / testing information is available and unscrupulous dealers are more than happy to palm off their defective wares on to the unsuspecting customers.
Here’s a quick guide to help you decide and purchase the right LCD TV for your home/office. Evaluate the LCD TV you intend to purchase against the following parameters.
1. Screen Size
Determining the right screen size is quite easy. It’s mathematical, hence precise.
1a. By Viewing Distance
To decide the screen size based on your viewing distance, multiply the distance (in feet) with 4 to get the screen size (in inches). For example if your sofa is 8 feet (96 inches) away from the TV, you need a 32 inch TV (8 x 4 = 96 / 3). Corollary, to determine the optimum viewing distance for your TV, divide the screen size (in inches) by 4 to get the viewing distance in feet.
1b. By Image Size
LCD TVs (wide-screen, 16:9 ratio) are actually smaller than their CRT TVs (4:3 ratio) for the same diagonal screen size. When compared to a 32″ CRT TV, a 32″ Wide-screen TV is smaller by 11% & presents an image that is 33% smaller in area. Hence, if you are looking forward to maintaining the same image size while viewing, be sure to choose a LCD TV that is 1.22 times bigger. For example, if you had a 21″ CRT TV, you need a 26″ LCD TV. If you had a 27″ CRT TV, you need a 32″ LCD TV. If choosing a TV by image size, be sure to calculate the optimum viewing distance using corollary presented in (1a).
This is where subjectivity comes in. Gamma is amount of light being emitted by lit pixels. If the gamma is low, then image will appear dim. Dark areas will be nearly black and detail will not be visible. If gamma is high, the image will appear very bright. Bright areas may appear to be nearly white and washed out making it impossible to spot pale colors.
Gamma is different from brightness where the brightness of the dark areas in the image is controlled. Gamma is different from contrast where the brightness of the light areas in the image is controlled. More often than not, gamma is property of the image-panel rather than the image itself.
A simple way to check for good gamma is to look for an image that has both dark areas and bright areas. For example images shot on a bright day. On a good LCD TV, the dark areas of the image will look nearly black instead of gray and bright areas of the image will represent the color of the area rather than just white. For example, light blue sky versus white sky, dark brown furniture versus black wood.
In India, National Geography & Animal Planet transmit high quality images all day that are perfect for gamma testing. Look for vibrancy in blue skies, green grass & red flowers. Ensure that none of these color appear fluorescent or washed out.
DVD/Blue-Ray Documentaries featuring high quality images:
3. Brightness / Contrast
“Brightness refers to how bright the shadows are and contrast refers to how bright the highlights are. So, for example, if you had a dark rectangle and a light rectangle on the screen, the brightness setting will affect the dark rectangle and the contrast setting will affect the light rectangle. If both brightness and contrast are set to minimum, the screen will be pure black. Brightness should be set so that black objects (like text, borders, etc) are pure black, but dark gray objects (shadows on buttons etc.) are still visible on a dark background. Contrast should be set to a comfortable setting, whatever you choose, if the monitor is too bright, turn the contrast setting down, if it is too dark turn the setting up.” —WikiAnswers.
While selecting the TV, note the headroom allowed in Brightness / Contrast settings in TV’s Setup. Most dealers set the TV to very high brightness and contrast. Try changing the brightness & contrast to 50% levels and check if the image is acceptable to you for day-to-day viewing.
Most TVs also use dynamic contrast where the brightness of the back-light is reduced in dark scenes to make dark areas nearly black (otherwise they appear gray). This makes it hard to determine if the TV features good contrast.
One way to check this would be to watch a movie with B&W scenes (for ex: Casino Royale). Look at the bright & dark areas. The white areas should appear milky white and not fluorescent white, while the dark areas should appear black or nearly black and not gray.
DVD/Blue-Ray Movies featuring high quality images:
The terror of Hue is back. In the earlier days of CRT TVs, images tended to have a distinct shift towards a certain color. Some TVs would display the images with green tint while others would display with a blue or red tint. Over a period of time, images on CRT TVs improved drastically and became life-like. One would assume that LCD TVs with their superior circuits would deliver the same if not better, but no. LCD TVs tend to display images with hue-shift or over-saturation; particularly when watching Cable/Satellite TV channels. This does not appear to be the case when watching DVDs on the TV, thus indicating a fault with the tuner circuitry rather than the panel itself.
The defect manifests itself to such a large extent in India, that most LCD TVs over-emphasize the red and Indian women look as pink as Russians in a sauna. If the entire image appears reddish/blueish/greenish, then the TV requires a Hue-shift. If the any one particular color looks almost fluorescent, then the TV requires Saturation-adjustment.
In India, change channel to a soap opera and look for skin tones of people. The TV with the most natural skin tone has no hue shift and has balanced saturation.
5. Refresh Rate
In LCD TVs, a layer of liquid-crystal acts as a gate to allow light to pass-through or block it. Since the transition from gate-open/gate-close takes time (in milliseconds), it is possible that in fast moving images, the gates do not open/close rapidly enough, thus leaving residual images (blurring) on the screen.
On slow LCD TVs, the blurring of the image in fast moving scenes is quite noticeable. To check for this, switch the TV to a financial channel that has a fast moving ticker at the bottom. Look for sharpness of the text in the ticker. If the text appears blurry, then the LCD panel is slow.
In India, ask the dealer to change the channel to CNBC-Awaz/CNBC-TV18. Look at the bottom of the image for the scrolling news. CNBC channels display this information at such high speed that most LCD TVs present a blurry text.
6. Audio Output
LCD TVs lack the physical depth that is essential for speakers to produce loud sound. Consequently, LCD TVs are blessed with tiny speakers that are good for watching news & documentary programs but terrible for music & movies.
Traditionally LCD TVs have been expensive and their owners have connected them to Amplifiers/Home-Theater systems to boost the sound. With LCD TVs now penetrating the middle class homes, the quality of sound on the TV becomes important.
In India, switch the TV to an English music channel like VH1 and listen for good bass & treble response. A TV with weak speakers will either have no bass-response or flutter every-time bass notes are played.
7. Computer Connectivity
For some people this option appears to be of no consequence and for others it is of supreme importance. At home, we use the PC Connectivity (VGA Connector) a lot to play movies off the Netbook (Asus EeePC, 8.9″ screen) and see the display on the LCD TV (32″ screen). Beats the hell out of burning CDs out of downloaded Divx/Flash videos or attempting to play formats like WMV & MKV which are not supported by my DVD Player.
The computer plays all formats so why not use that as the ideal movie/music player?
A big fail in many LCD TVs is their inability to report the specifications of the display panel to the computer using Display Data Channel (DDC) feature of the VESA connectors (aka VGA Connector). This results in computers not being able to detect the optimal resolution of the TV. Thus the computer is not able to display image that takes advantage of the display resolution of the panel. On such TVs, the computer is forced to output a generic 1024 x 768 pixels image that is scaled by the TV internally and results in blurry distorted image.
In India, LG TVs were the only ones to report the DDC information correctly and my laptop switched the display resolution all the way up-to 1920 x 1080 pixels. If possible, carry a laptop and VGA cable with you into the store to test TVs for computer connectivity. This becomes particularly important if you intend to check for pixel defects.
8. Pixel Defects
This is a sticky issue between manufacturers, retailers and customers. LCD TVs are immensely complex to manufacture and they often suffer from defects where individual pixels fail to work as expected. In LCD TVs, this is caused by the tiny LCD Light gates either slamming permanently shut or permanently open. Defects may also be present in the CFL Back-light.
LCD Pixel defects are primarily of two types: Full-pixel defect or Sub-Pixel Defect. Each white pixel is made up of three smaller pixels (sub pixels) of red, green & blue colors. If any color pixel develops a defect, it’s known as sub-pixel defect. If all sub-pixels develop a defect, it is known as a full-pixel defect.
Every manufacturer’s policy on replacing LCD TVs that have developed pixel defects is to tolerate a few and replace only if the number of pixels in substantially large. Quite unhelpfully, they fail to declare the exact parameters of pixel defects replacement policy in the warranty.
In India, this is a double-whammy since no retailer has the capability to test for pixel defects and more often than not, they refuse to ship from store; promising a delivery from their warehouse instead. This is a potential trap for customers.
As a customer, you walk into a store to select a particular brand-model, and you pay for it. In big stores, the TV will not be delivered to you on the spot, instead it will be delivered to your home from the warehouse. This means that you are receiving a product which you did not test at the store to your satisfaction but have already paid in full. The moment you walk out of the store having made the payment, the dealer is out of the picture and now it is between you and the manufacturer of the TV. If you discover at home that the TV delivered to you has pixel defects, you cannot approach the dealer for a replacement. You will instead have to run-around the manufacturer’s office trying to explain to them the defect. The manufacturer will point out a paragraph in your warranty that states “LCD TVs are hard to produce without pixels defects; hence some pixel defects may exist and are acceptable by industry standards”.
Not only you have paid a substantial sum of money for this TV, but you were also denied the opportunity to test it to your satisfaction to receive a new unit in lieu of the defective one.
As a customer, insist on store delivery and testing. If the store does not have ready stock, offer to make a repeat visit. If their policy only permits warehouse delivery, then opt to walk-out. Small retailers generally maintain stock at their retail outlet and they may present a better option.
To test a LCD TV for pixel defects, carry a laptop and VGA cable. Install a test tool like IsMyLcdOK. To test, look closely at the screen:
- in black screen, look for white/colored dots. These are stuck pixels (LCD light gates that are stuck open).
- in white screen, look for black dots. These are dead pixels (LCD light gates that are stuck close). You can also look for colored dots instead of full-white dots, but in my experience this is tough.
- In red screen, look for black dots. These are dead sub-pixel.
- In blue screen, look for black dots. These are dead sub-pixel.
- In green screen, look for black dots. These are dead sub-pixel.
- In gray screen, look for uneven brightness. This is a defective back-light.
- In horizontal / vertical gird, look for interference. This represents failure to optimally lock into the VGA signal
9. HD Ready vs. Full HD
All LCD TVs sold today are wide-screen (16:9) and either feature HD-Ready resolution (1366 x 768 pixels, 1 million pixels) or Full-HD (1920 x 1080 pixels, 2 million pixels). HD-Ready TVs can generally display Full-HD images in interlaced mode only (1080i).
It is important to note that while TVs are ready to display the next generation of video, the broadcasters are not.
In India, most popular video formats are: Video-CD (352×288 pixels), DVD-Video (720×576 pixels), Broadcast TV (720×576 pixels). All of these fall woefully short of even HD-Ready standards. As a result, the image is scaled up and displayed. This results in a soft-focus image on TV and lack detail. Since broadcasters in India still use 4:3 resolution, the images also appear horizontally stretched on the 16:9 displays. Anorexic models look like well-fed happy housewives.
If you are the type of user whose primary use of the LCD TV will be to view broadcast TV, HD-Ready is good enough. If you are the type of user who professes love for cutting edge video and already possess/about to purchase a Blue-Ray Disc Player, you should ensure that your TV is Full-HD (1080p) compatible.
DVD/Blue-Ray Test & Calibration Videos:
This is generally overlooked, but can cause quite a bit of heartburn later. When buying a TV, ensure that the following inputs are present.
- Composite Video (Red-White-Yellow): At-least 3 of these are required (AV1, AV2, AV3) to connect a Set-Top Box, DVD Player/Set-Top Box & Handy-Cam/Old Game Console
- Component Video (Red-Blue-Green-Red-White): At-least 2 of these are required (maybe shared with AV1, AV2) to connect a DVD-Player, New Game Console
- S-Video (Round Black connector with 4 pins): At-least 2 of these are required (maybe shared with AV1, AV2) to connect a DVD-Player, New Game Console.
- HDMI (Single flat connector with contact strips): At-least 2 of these are required (maybe shared with AV1, AV2) to connect a DVD-Player, New Game Console/Computer
- VGA (Single Connector with 15-pins): At-least 1 of this is required to connect a computer. Audio from computer maybe received using an additional stereo-pin connector (desired) or shared with AV port.
- Composite Audio-Video Out (Red-White-Yellow): At-least 1 of this is required to connect the audio-output of the TV to an amplifier/Home-theater system.
I hope to have educated and entertained you with this article and as a happy educated buyer, you are now capable of buying the perfect LCD TV for your home. Your feedback is most welcome.