By: Alan D. Mendelsohn MD
It’s hard to not walk into any big box retail store and not be seduced by big, bright new TVs declaring the years latest innovations, leaving us to naturally feel insecure about what we have in our living rooms at home. Making the decision to upgrade isn’t easy given the acronyms, terms, and sales jargon used by manufacturers, but there’s a simple reality that can cut through the noise and provide simpler answers: the limitations and preferences of the ultimate input device, the human eye.
Resolution is by far the most touted innovation at the store. SD to HD to 4K and UHD and beyond. In practice, these simply mean how much data is being used to create the picture you see. The higher the resolution, the more data the screen can render. So on a small screen, HD content will look crisp and sharp. The same resolution on a larger screen will look pixelated and grainy. The move from SD to HD was quite welcome and noticeable, but the move from HD to 4K and UHD, is often noticeable until you’re watching a big TV or are up quite close. To put that in context, if you have 20/20 vision and are 10 feet away from a 50 inch screen, you won’t notice a difference between HD and 4K. In fact, you would have to be about 5 feet away from the 50 inch screen to start appreciating the higher resolution and 3 feet away to get the full benefit of 4K. Of course watching a 50 inch screen from 3 feet away causes tremendous eye strain, nevermind makes taking in the full content quite difficult. The majority of TVs owned in the United States are smaller than 50 inches, and the average American sits over 9 feet away from their TV.
As an additional note that might give pause before making that upgrade to 4K from your trusty HD set, very few broadcasters output their signal higher than HD. Cable and satellite TV providers have just begun to show occasional 4K content. For sports fans, it’s worth noting that most programming, including ESPN, is broadcast at 720p. In fact, only as of March 1st, were broadcasters allowed by the FCC to broadcast using a standard that allows for 4K broadcasts, and at their discretion. Which means more 4K content is coming, but for now, you’re limited to 4K content from services like Netflix using an Apple TV or Roku or your TV’s built-in smart features. And the resolution of 4K TV will do little to improve the experience for sports fans. But a 4K picture, is, unquestionably, sharper than traditional HD..
What does matter, however, are a few innovations that are less touted but have a bigger impact on your viewing experience. Among them, the ability of displays to create a true black, and the refresh rate of our displays.
LCD and LED panels, which make up the vast majority of new TVs all require powerful lamps within either the frame of the TV or behind the panel to illuminate the little chips rendering the colors that make up the picture. Those bright lamps remain on as long as the TV is showing an image. Which means the contrast the TV shows is limited, it can’t produce black, only a shade of gray. You’ve probably seen it while watching a movie with a dramatic night scene, and it’s hard to pick out the detail of a figure moving in the shadows. In a natural environment, our eyes are quite good at adjusting to low and high contrast environments. A brightly lit TV means our eyes can’t adjust to see the lower contrast image, and it just looks washed out. Newer TVs, touting HDR and other innovations have emerged more recently to help boost the dynamism of the colors we can see in an image, particularly in a high contrast environment. But LED and LCD TVs still can’t render a true black. Self-proclaimed A/V geeks like my son swear by their plasma TVs, hard to find these days, because they use different techniques to render a picture. OLED TVs are the latest innovation, still hard to find as there’s on manufacturer, LG, who manufactures all the large OLED TV displays in the US (Sony buys LG displays and repackages them) and they remain quite expensive. OLED pixels have that bright light on each pixel, meaning turning off a pixel renders a true black and very high contrast. As the availability of OLED goes up and price of OLED comes down they will be a new standard and worth the upgrade.
Finally, the rate at which the TV can render an image is worth considering. All TVs support 60Hz, or 60 frames in a second, a legacy of the US electric grid. That’s good in most instances, because at that rate, our brains begin to stitch the images into what we perceive to be natural, continuous motion, instead of a sequence of images. Films are still most often shot at 24Hz, which means TVs have to fill in the gaps between images so they can be displayed. Newer TVs, however, support refresh rates quite a bit higher. Most of this is marketing hype with little perceptible effect. If content isn’t filmed at a higher refresh rate, or it isn’t delivered to your TV at that higher rate, your high refresh rate TV is just filling in gaps you aren’t going to appreciate anyway. Or in my experience, sometimes make the image feel unnaturally and off. [Note for editor: this is why you will see 1080i and 720p. Interlaced will produce a sharper image, progressive will produce a faster image. 4K and higher standards are all progressive. This is pretty wonky. 1080p, which most HD TVs bought in the last 5 years can render, is perfectly good enough, and what you find on Bluray or via a streaming service.]
And yet, there is one group of TV purchasers that benefit from the innovations: video gamers. Folks playing video games tend to sit much closer to their TVs than those watching more traditional programming. And the latest game consoles, and certainly gaming computers, can support very high refresh rates. When you’re in the heat of battle, chasing down a digital opponent, that extra resolution and fast response may improve your gameplay. But I say may because at the end of the day, we’re all human; our eyes and brains can only process so much, so fast. The latest graphics processors can render images far faster than we can perceive. Which means we’re being sold features we simply don’t need.
Focus on contrast ratios, don’t buy into the resolution and frame rate hype. Unless you’re sitting very close to a very big screen, it’s not going to make a difference for you.