It's not resolution. Nor is it size of the screen or price of the TV. It's the contrast ratio that makes all the difference in picture quality between two otherwise identical TV sets.
This might seem counterintuitive, because TV manufacturers have led us to believe TVs with a better resolution create significantly better images. Presumably, you have come across TV ads that say that a 4K (or Ultra High-definition/UHD) TV with a resolution of 3840 X 2160 produces better images than a Full HD TV with a resolution of 1920 X 1080.
In reality, it is contrast ratio, not resolution, which decides how good an image should look on a TV screen. Of course, resolution plays a part in creating better images, but that is not as important as contrast ratio. After all, a TV (or any display for that matter) is all about how lifelike images and videos look on it. Higher resolutions or larger screens do little to make images more convincing.
So, what is contrast ratio?
Put simply, contrast ratio is the difference between the brightest part and the darkest part of an image. The difference is quantified as ratio, hence the term 'contrast ratio'. If a TV has 100 to 1 contrast ratio, it means whites in the image are a hundred times brighter than blacks in the same image. The wider the gap is, the more realistic the image will be.
Without substantial contrast ratio, whites and blacks in an image shy away from being absolute blacks and absolute whites. As a result, the image looks washed out as opposed to appearing rich and vivid. To put things into better perspective, watch 'The Dark Knight' on your LCD TV. An abundance of blacks characterises this particular film. If these blacks look washed out on your TV, chances are it is plagued by a poor contrast ratio.
Native vs. dynamic contrast ratio
Native contrast ratio is what the panel itself can conjure up. OLED and now-defunct plasma panels have better native contrast ratio than LCD panels.
However, LCD panels have found a way around it. They use LED backlights (hence the term 'LED LCD TV') to achieve desired contrast ratio. In dark scenes, the intensity of the LED lights is reduced to achieve blacker blacks. The intensity is notched up to get whiter whites during bright scenes. This whole technique of manipulating LED backlights is called dynamic contrast.
So, the next time you buy a TV, do not evaluate it by resolution only. Or do not let the showroom sales people throw a bunch of baloney at you on resolution. Ask them about the contrast ratio of the TV set you have your eye on. Chances are you will get a vague reply. Therefore, your best bet is to do some investigative research on TVs on the internet and shortlist them based on your desired features and budget. After all, a TV is the most important bit of equipment for your home entertainment centre. A great deal of research deserves to go into it before making any final purchase.
By Tanvir Sufi