Thursday, April 28, 2016

HDTV Overscan

HDTV Overscan: What It Is and Why You Should (Probably) Turn It Off


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Here’s something you may not know: that HDTV that you love so much probably doesn’t show the whole picture on its screen. In fact, up to five percent of the picture can get cut off around the edges—this is called overscan. It’s old technology that’s left over from the CRT (cathode ray tube) televisions of yesteryear. Here’s why it existed in the first place, why it’s still used today, and how to (hopefully) turn it off on your TV.

What Is Overscan?


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Travel back in time with me, if you will, to a time when LCDs, Plasmas, and other ultra-thin television technologies didn’t exist. To a time when huge, heavy CRT televisions ruled the living room (I know some of you are trying to forget those day, I apologize). It was a dark time for TV watchers.

Back then, the combination of various-sized CRT TV screens and an absolute lack of standardization made it incredibly difficult for content creators to ensure that everything would display properly on a given television. The answer was overscan, which essentially cuts off the edges of the picture to ensure all the important stuff shows up on the screen in a pleasing way—no content gets cut off, nothing is off-center, and no black bars appear due to a picture being resized. Makes sense, right? The odds are that the little bit of stuff that gets cut off around the edges of the picture isn’t really that important anyway.

In fact, content creators defined three areas of all displays so they could make sure all content would display correctly:


  • Tile Safe: The area that virtually all televisions would show, confirming that no text would be cut off.
  • Action Safe: The larger part of the viewing area, which was defined by the highest TV set calibration.
  • Underscan: The full image.

This sort of standardization gave producers and directors a guideline to go by so nothing valuable was lost, but also ensure that nothing was left on-set that would later show up on-screen for televisions that showed more of the picture than others.

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In other words: it’s complicated, a real pain to deal with, and none of the same rules apply today. But overscan still exists.

So Why Do Modern TVs Still Use Overscan?


Overscan is not required by any modern “fixed-pixel” high-definition televisions, like LCDs. In fact, the crop-and-zoom method of overscan often reduces picture quality, making it something that is not only unrequired, but undesirable. Think about it: If you have a video that measures 1920×1080 pixels, and a TV screen that measures 1920×1080 pixels, but your screen is zooming in–you aren’t getting that perfect pixel-for-pixel image.

In addition, if you hook up a PC to your TV—say, for use as a home theater PC or for gaming—it’ll often cut off part of the taskbar or menus, making it difficult to use.

So if overscan is so unnecessary–and bad for picture quality—why do HDTVs still use it? While not a simple concept, TVs still use overscan because content creators still use it, and TV manufacturers have to follow their lead.

Overscan also serves another, lesser-known purpose. Since the outside area isn’t going to be viewed anyway (in most cases), it’s used to house important data for analog-to-digital converters. Analog has no way to attach additional information to the picture like digital does (metadata), so this data is tucked neatly into things like blinking pixels or scan lines—think of it as Morse code for TVs. While the majority of everything is completely digital from end-to-end now, there are still some analog-to-digital conversions going on. That’s the problem with old technology that was so widely adopted and use for so long: it’s almost impossible to get rid of it completely.

So since it’s still out there and being used, TV manufacturers keep doing the overscan thing, even on modern TVs. This, of course, is incredibly annoying—especially for non-broadcast content, like games or Blu-rays.

How to Disable Overscan on Your HDTV


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With me so far? Okay, there’s good news: most TVs have a way to disable overscan. But there’s also bad news: it’s not always that straightforward. Nothing good can ever be easy, right?

Start by grabbing your TV’s remote and pressing the Menu button. Head to your TV’s picture settings. If you see something called “Overscan”, your life is simple: just turn it off.

If you don’t see that setting, however, it doesn’t necessarily mean it’s not available on your set—it probably means that the manufacturer decided to change the name to make it “easier to understand.” In that case, you’ll have to either keep digging and tweaking till you find it, or you can do the unthinkable: read the manual. Do you even still have the manual? Probably not. I bet you can find it online.

Since we’re basically friends, though, I compiled a quick list of some of the most popular manufacturers and what they call overscan on their sets:


  • Vizio: Change the picture mode to “Normal” (if it isn’t already). This automatically disables overscan.
  • Samsung: Look for the “Screen Fit” option.
  • Insignia: In the advanced options menu, it’s surprisingly called “overscan.”
  • Sharp, LG, and Philips: Unfortunately, we couldn’t find a good consensus on these three brands, so you’ll probably just have to Google it for your specific model.

These won’t necessarily be exact for every individual model, but they should set you in the right direction. Once you’ve found the correct setting, you can just disable it (or tweak it, if allowed) and you’re done. Enjoy all that content you never got to see before and didn’t even realize it.

Check Your Set-Top Boxes, Too


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That’s not all, though! Many set-top boxes—like NVIDIA SHIELD, Amazon Fire TV, and Apple TV for example—also have their own overscan settings. So even if your TV has overscan turned off, your set-top box might still be stretching the picture. In some cases, it could even be an underscan option, which zooms out on your video in order to overcome the downsides of overscan.

So, once you’ve got your TV working properly, check your set-top boxes, game consoles, and DVD or Blu-ray players for any overscan or underscan options. Like the TV, it may not be labeled as “overscan,” so don’t be afraid to experiment. And of course this will only apply to that connection. If you change the overscan settings on your streaming box, for example, it won’t have any effect on other inputs, like your cable box.

Amazon Fire TV, Apple TV (4th generation), and some Android TV boxes should all have options to adjust overscan in some way,

Overscan is archaic and outdated, but unfortunately as long as analog connections exist and content creators continue to use the overscan area, it’s not something we’re going to get rid of. At least you can disable it on most modern televisions though, so you can get rid of it in your own living room. Welcome to the new world.

By How to Geek

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