How Does HD Work?
High Definition video is everywhere these days. It’s to the point where the very definition of, “High Definition” should be changed to “Standard Definition”. However, while we all know what HD looks like, it’s harder to describe what it is. There are several variations of HD marketed to the consumer: 720p, 1080p, and 4k. The climbing numbers are supposed to indicate a climb in quality. Though this begs some questions. What does HD quality truly mean? Does it matter? Is there a limit to the quality of HD? An HD image might be clear as day. Yet, explaining what an HD image is, and what makes it that way? That takes a bit more work.
The quality of an image on a device comes down to pixels; small squares of color, that make the resolution. More specifically, resolution is defined by lines of pixels. A 480p (standard definition) TV is has 720 x 480 lines. This is a total of 345,000 pixels — quite a lot, especially on a small screen. As the screen size increases though, and one doesn’t increase the resolution/number of pixels? 480p’s 345,000 pixels doesn’t exactly cut it. When the size of a screen increases, pixel density decreases; this is the pixel paradox. Larger gaps have to be placed between the pixels on a 480p TV screen, as opposed to a 480p phone screen. These gaps will ultimately make a larger screen (such as the TV) blurrier, and the smaller screen (such as a phone) sharper..
That said, there’s an easy way to obfuscate gaps caused by low pixel density: increase the pixel density. In other words, increase the number of pixels. This is what drives the technology behind things like 4K HD (also defined as 3840 x 2160, or 8,294,400 pixels). An increase in the amount of pixels allows one to easily jump from a 20 inch TV to a 200 inch TV — supposing that the spirit and wallet are willing — without sacrificing image quality. The cost of larger screens has probably been the biggest barrier to increases in screen quality. While the technology might be there, the expense of producing massive screens, with massive amounts of pixels, is — you guessed it — massive.
Nevertheless, how big can image quality get? In 2019, Sony produced a 16k tv. While it’s difficult to say where our technological limit is, it would not surprise me if a 32k TV is on the horizon. That said, there are drawbacks to massive increases in HD quality. Namely, bigger screens are required to truly appreciate the effect of bigger resolutions. To the human eye, there is little difference between a 1080p and 4k phone screen; much less a 16k screen. Moreover, higher numbers of pixels also place strain on the refresh rates of video cards, causing choppier video. Finally, there are few cameras that can produce images to the quality of 16k. Thus, without significant technological advances on multiple fronts, the point of producing screens with 16k or 32k capability is pretty useless.
As stated before, there is an extent to which image quality truly doesn’t matter. A 16k television won’t sell if our vision can’t tell the difference. Yet, it’s because of this that it’s so important to be informed about the discrepancies between types of HD, and the way in which HD operates. Big terms like “Ultra HD” might elicit feelings of magic or pixie dust; but behind the marketing smokescreen, one’s phone or TV screen is still just pixels.
