The Number of Pixels
There’s many terms to designate that a TV has high definition: a 720p HDTV, a 1080p HDTV, a 4K Ultra HD TV — these are all numbers that refer to how the TV’s screen displays images. An image is made out of pixels, and the more of them they are, the more densely they are packed together. This results in a “tighter” and more focused image, where there is greater detail. On a practical level, this also means how far away you have to be from the TV for the image to resolve. For example, stick your face right up to the screen of a 4K UHD (careful not to touch!). You’ll find that the image isn’t being broken up and blurry. That’s because of the high pixel count. On a practical level this means you can be closer to the TV without suffering any negative viewing effects (i.e., the picture is sharp and clear). Depending on the size of the room or number of people viewing, this can be significant.
The Contrast Ratio
Contrast is defined as the difference between light and dark. On a TV this means the difference between the brightest white and the blackest black that can be generated. Specs for TVs note numbers like 10,000:1 or 50,000:1 or higher, but on a practical level the contrast serves to help define the objects on the screen from other objects — a “dry” way of saying that a person walking across a street doesn’t get blended into the background, or that you can “see” into a dark alley rather than it looking like a black wall. Contrast also works to sharpen a scene and so aids in making details seen. New technologies like those found in an Organic LED (OLED) 4K UHD TV are so designed so as to be able to provide an infinite contrast where the blacks, for example, are so near-perfect that the TV turned off looks the same as when on (from the “black” point of view).
LCD flat panel TVs are a mainstay today, and as amazingly thin as they are, there are still technologies between the back the display and the front affecting the view being seen. These backlighting technologies work to illuminate the image. One type is called “Edge-Lit”, because the lights are set at the edges of the frame encompassing the display, while the other is “Full-Array” and is inside and against the screen in a grid-like pattern. A visual difference between the two is that “Edge-Lit” allows for a thinner display, but otherwise “looking” at the picture is still the best guide to which is preferred. With that in mind, both of these types can also include “local dimming” which enables local areas to be illuminated independently. This greatly enhances the picture of the TV, as does the use of LED for the backlighting — keeping the set slim and adding brightness, clarity and color detail.
Choosing a TV is personal so don’t let all the tech terms confuse. Combine checking into the specs with how the picture looks to you. Then figure in where you want to put it and where you’ll be sitting when it’s first turned on. That will be a joyous experience.