Wednesday, December 29, 2010

Aspect Ratios and other Tips

After all the hard work of choosing your HDTV, the TV is delivered and now is the time to switch on the new toy, sit back, relax and enjoy the fruit of your labour. But what, why is the picture not looking as good as in the showroom? Why are there black bars on both sides of the screen? Why do all the people look fat and distorted on my new screen?

Here are some answers. Your HDTV will only look good and proper when displaying HD source materials at the correct aspect ratio. If you are watching your old VCD, DVD or SD (standard definition) TV broadcast, your HDTV will not magically make them look like HD. You need to have HD source materials to display or you will be disappointed. In fact some SD material will look worse since the higher resolution of the HDTV actually magnifies the old SD material and the imperfection will be more apparent.

All the material they play on the HDTV in the showrooms are specially prepared demonstration material or selected Blu-ray Disc (BD) movies to bring out the best in the HDTV visually. (The current favourite demo movie seems to be Avatar.) So your run of the mill HD material may not be as good as the demo items but definitely better than normal SD material. Your best source of HD material is undoubtedly BD movies, both visually and also audio-wise. Alternatively, downloaded HD movies and TV series (legally or otherwise) are getting popular and these can be played on your HDTV with a HD Media Player.

Another good source will be HDTV either delivered on cable or via satellite service (like the local Astro Byond). In the more advanced countries, they will have VOD (video on demand) or HD movie rental via the internet. To enjoy your HDTV to its full potential, you must get one or some of these HD programme as the source. Just note that not all HD movies or programmes are created equal, you will find some looking better than others so do not expect all of them to be of demonstration quality.

What about the black bars on the sides and the distorted picture that fill your screen? This bring us to the aspect ratios of TV screen. The older CRT TV and PC monitors have squarish screen size that is referred to as 4:3, i.e 4 units wide and 3 units high or an aspect ratio of 1.33:1 (which is 4 divided by 3) and this is called standard screen. When HD program came along, a standard screen size for HDTV is 16:9 i.e. 16 units wide and 9 units high or 1.78:1 (16 divided by 9 = 1.777 and is rounded off to 1.78) and this is known as wide-screen. Even PC monitors nowadays are wide-screen at 16:9 and 4:3 monitors are a rarity.

Those anomalies we see is because of these 2 different aspect ratios and we will limit ourselves to what we see on the HDTV. If you watch standard SD material (those with 4:3 settings) you will see black bars on either side of the HDTV since is is wide-screen and hence too wide for SD material. For some people, having paid so much for a new HDTV, they would want to fill up the whole screen to fully utilise their investment. There are at least 3 ways to do it and most HDTV will have these options or more. The first one is Full (or call Stretch in some brands) so the SD material will be stretched sideways and people will look fat and squashed. This is the one used by most people. The second one is to use the Zoom function to fill the screen with the picture. In this case, the SD material is made bigger all round, keeping the right proportion but then the top and bottom part of the picture will be missing. The third option is less common where the stretching is done at the corners to fill the screen and the result is that distortion is more at the corners while the centre is near the correct proportion. This is called Super Live, Panorama, Theatre Wide or some other term as used by different manufacturers.

Actually getting a HDTV is to get the best picture so using any of the above 3 methods to get rid of the black bars at the side is really sinful since it will result in distorted picture or missing parts of the action. One should live with the black bars but then it is up to the individual so as a result we see a lot of fat and squashed people on HDTV screens.

Just a word of caution for new Plasma TV owners. Though there is great improvement in this area, there is a possibility of image burnt-in for Plasma TV, especially during the early or run-in period; each model has different run-in period so check your user manual. During this period, avoid prolonged period of black bars on either side, i.e. view your material in full screen even if it is distorted. After this you can choose whatever settings you like. LCD TV do not have this image burnt-in problem.

How come sometimes I can see black bars at the top and bottom even though I am playing a Blu-ray disc, shouldn't the picture fill the whole screen? Well there is nothing wrong with your TV it is just that not all movies are shot at 16:9 (or 1.78:1) as some are extra wide at 1.85:1 (which is the standard 35mm movie ratio) and even 2.39:1 (CinemaScope or panavision ratio) so if these are shown on the HDTV screen, there will be black bars on the top and bottom as these movies are wider than the HDTV screen. To get rid of these bars, you can zoom your TV but you loose out parts that are on the sides. Again, it is best to watch with the black bars as you will be watching the movie in the format the director intended.

If you are having a HDTV for the first time, the first thing you must do is to set your DVD or Blu-Ray disc player to display on wide-screen TV or 16:9 Normal so that your movies will be shown in the correct aspect ratio without distortion or losing part of the picture.

On some HDTV, there is a selection for Store or Home so you should set it to Home for normal home use. In the Store mode, the brightness and contrast is preset to the maximum to attract attention. That is another reason why the TV looks good in the shop as it needs to compete with all the other models. But this shortens the life of the TV screen so the Brightness and Contrast should be turned down for home use. More on calibration in another post later.

To get the best picture quality on your HDTV, always use a HDMI cable for all your connections to the picture source. And you do not need to get a monstrously expensive HDMI cable, just one from the hypermarket or corner PC store will do. As the signal is digital (just ones and zeroes), either the signal is there or is not and thus either the cable works or it does not. Nothing in the cable will make the picture look better, even if it cost a bomb.

Ronald Kwok

Thursday, December 23, 2010

HDMI and other Inputs

If you have followed my previous posts, you would have narrowed down your choice of a HDTV. There are other features that you may want to consider before making the final decision.


HDMI inputs
The more the merrier. Make sure there are enough HDMI inputs to connect all your intended equipment with HDMI outputs. Normally you will need at least 3 (depending on your set-up) - one for you cable/satellite TV box (like Astro), another for your DVD/BD player and the third one for your gaming, camcorder, HD Media Player and other gears. If you have the newer AVR, then this number is not so important since you can connect most of your gears to the AVR HDMI inputs and with just one HDMI cable out to the HDTV. If your chosen HDTV do not have the number of HDMI inputs required, you just have to pull the cables in and out when necessary or maybe you can get one of those multi-HDMI (many in, one out) adaptor.

RCA connectors
To connect your DVD player or other gears without HDMI output, you will need either the composite terminals (red, white, yellow) or component terminals (red, blue, green). Most HDTV will have both these inputs, otherwise choose the one with the component inputs since this will give a better picture on the HDTV. S-video input is now less common.

RGB/PC terminal
You will need this if you intend to connect up your PC or laptop. Most if not all LCD TV has this, but for Plasma need to double check. You should go for a Full HD model if you want to hook up a PC or the lower resolution will show up.

USB and Memory Card slot
Some models have a USB slot to connect a thumb drive or external HDD to play music, photos and videos but the video files format support differs from model to model. Some have a Memory Card slot (like Sony and Panasonic to support their cameras and camcorders directly) for you to view photos and videos. Personally, I feel it is better to get one of those HD Media Player which is more versatile and has more functionalities then the ones built-in with the HDTV.

Other features

Screen style
Plasma screen usually reflects more light while LCD are normally matte but newer models are more glossy so you need to pick the one that best suits your viewing environment. Too much reflection will spoilt your viewing enjoyment.

Viewing angle
LCD can never beat Plasma in this area. All LCD TV will have a smaller viewing angle than Plasma but this differs depending on the make. Look from the sides of the LCD TV to see how bad the image is affected but in practice it is not critical since most of us will be watching from the front and not too much from the sides of the TV.

Cinema Mode, 24p
This is also called Real Cinema, Real Movie, etc. by some brands. Movies are shot at 24 frames per second (24p) while the normal rate for videos are 30 frame per second (30p) in NTSC or 25 frames per second (25p) in PAL. So to get the right movie feel, some HDTV have this 24p cinema mode. Note that this will only work if the source is also output at 24p and Blu-ray Disc players can do this. Like in many other features, some models of HDTV can do it better than others. To most people, the improvement is slight and many people cannot see the difference unless the two rates are displayed side by side. So this is more for the purists and videophiles.

Generally, the bigger the set, the better the sound and the higher end models will sound better than those at entry level. But really, to complement the HD video, you should hook up an AVR to enjoy the HD sound, especially from Blu-ray discs for a complete enjoyment of HD.

Picture Adjustment
Calibration enthusiast may want to check what parameters are available for tweaking. All HDTV will have enough video/colour adjustments provided than most of us can handle.

Intra-brand Connectivity

If your already have equipment from a particular brand, you may want to consider the advantage of getting the HDTV of the same brand (if the critical specs meet your requirement) such as using one remote control for all the equipment.

WiFi and Internet connectivity
Some higher-end models may have these functions. Only you can decide if you really need these, at a cost.

Finally, there is the physical built and how the HDTV looks and blends in with the rest of the furniture. For that, we better leave it to the wife or mistress, oops, I mean the missus.

Ronald Kwok

Wednesday, December 22, 2010

Contrast Ratio, Response Time, Refresh Rate

There are some specifications for LCD TV which potential buyers may want to compare but find confusing. The two common ones are Contrast Ratio and Response Time or more commonly used now, the Refresh Rate. For Plasma TV, these are not issues since inherently Plasma TV are better than LCD TV in these two areas. The first one, Contrast Ratio, should be totally ignored as this is the one spec that is really useless and often misused by some manufacturers.

By definition, contrast ratio is the ratio between the brightest white and the darkest black a TV can display and you see figures ranging from 30,000:1 to the ridiculous 5,000,000:1 or even higher quoted by some manufacturers. Does it mean that the later is 500 times better than the earlier one? Definitely not.

Here are the reasons why you should not look at this Contrast Ratio at all. Firstly, manufacturers do not tell you how they come up with the figures as there is no standard agreement among manufactures on how this should be done so it is free for all in this area and some manufacturers keep on increasing this figures hoping to boost sales in the process. So it is pointless to compare figures between manufacturers. These figures are probably measured in a totally dark laboratory and once there is some ambient light where we put the HDTV, these figures go out the window. Secondly, our eyes can only differentiate contrast ratio of up to about 1,000:1 normally so anything above that, the difference is not noticeable unless you are a robot. These fantastic figures are measured for static images so it has no meaning when we watch movies on the TV.

Among manufacturers, LG seems to be quoting higher and higher contrast ratio figures while Toshiba is using a comparatively modest 50,000:1 for all their LCD TV. Samsung used to be like LG but now it does not quote figures but just uses terms like "high" and "ultra" (do not know what they mean but it does not matter). Not sure what other manufacturers are quoting but whatever figures they use, you can just ignore them. Contrast Ratio is not the only item that affect the quality of the picture and in any case, it makes no difference in the real world for watching movies.

(Plasma TV has better Contrast Ratio than LCD normally by virtue of the technology employed so there is less number games for this in Plasma TV specs.)

Another specification is harder to classify, that of Response Time. This figure used to be quoted frequently earlier (especially for gamers) but not so much now simply because the technology for improving the response time of LCD has more or less reached the limit. This item measures how fast an LCD pixel can change state so the smaller figure the better. This used to be in 10's of milliseconds but now it is like 5ms or down to 2ms for some models. Anything 5ms or below should be OK for normal use and in practice the difference is not very noticeable after that. A slow response time will result in motion lag, smearing or trailing effect for fast moving objects in action scenes or sports. (In reality, there is also no agreed standard on how this should be measured and quoted by manufacturers but for simplicity, we assume that this is done more or less similarly and the figures should be used just as a guide; anyway, the discrepancies are not as great as those seen in the Contrast Ratio figures.)

In order to improve the response time, manufacturer is now resorting to increase the refresh rate of the TV to give them another opportunity to play the number game of higher is better. The original refresh rate used is 50Hz (for PAL land like Europe and Malaysia) and 60 hz (for NTSC land like USA and Japan) and newer LCD TV have double or 4 times this to 100Hz or 200Hz (or the corresponding 120Hz and 240Hz for USA and other NTSC countries). The average human eye can discern the improvement from 50 Hz to 100 Hz (or 60 to 120Hz) but the next improvement to 200Hz (or 240Hz) may not be so apparent to some. The newer LED TV are pushing this even further to 400Hz (or 480Hz) but it is doubtful if the normal human eye can see the difference but it does help manufacturer to sell more of these TV sets and make a better profit. Manufacturers are using different terms for these higher refresh rates to attract customers, such as TrueMotion, MotionPlus, MotionFlow, Natural Motion, etc to give the impression that their technology will enable the HDTV to display smooth motion.

Each manufacturer uses a different technology to implement the higher refresh rates so results will be different and some are more effective then others. In addition, a lot depends on the source material itself so if it is bad, no amount of refresh rate will improve it and it may even show up the weakness more. Thus the increase from the standard refresh rate to the higher rates may or may not be a visible improvement for some brands. To really compare, you must play the same source material on two different sets and watch them side by side. If there is no noticeable improvement, go for the lower refresh rate model which is usually the cheaper one. Again, use your eyes as the judge.

In summary, you should totally ignore the Contrast Ratio figures. For the Refresh Rate, you can compare the figures from different manufacturer up to a point as a guide as higher figures are hard to discern visually in real life. This will also vary from model to model. The best is to use your eyes as the judge, not the figures produced by the manufacturers as they are there to impress and sell their products. A good image is not due to just one or two items of the specs but it is a complex mixture of many other factors.

In fact, a finely calibrated entry level HDTV will give a better viewing experience than a badly calibrated high end unit. As an analogy, a well-tuned Proton will perform better than a badly tuned BMW. OK, maybe this is stretching it a bit but I think you get the idea!

Ronald Kwok