OK, here we go. For the purposes of this post, I am going to assume that people either have a High Definition TV or an old style Analog TV. The other types (SDTV and EDTV) are not as popular and those who have them can figure out where they fit into these scenarios.
High Definition Televisions are wider than regular TVs. That's why they call them Wide Screen. Not to get too complicated but Analog TVs use a 4:3 ratio (picture it 4 inches across and 3 inches high). HDTVs us a 16:9 ratio (16 inches across by 9 inches down). That's a big difference. An HDTV is almost twice as wide as it is high. To make things more confusing, movies in the theater are in a 1:2 ratio, twice as wide as they are high. So when a movie plays on TV, even in HD, they still have to cut off part of the picture.
I want to talk about the most common scenario so let's assume you have a High Definition TV, subscribe to cable or satellite, and pay extra for the high definition TV package offered by your provider. You are channel surfing. Some of the channels are High Definition channels (meaning they are HD capable) and some are regular or non-HD channels. In this scenario sometimes you will have control over how the picture fills your screen and sometimes you won't.
If a digital TV broadcast is simply that, digital, and not high definition, then by default it will be in 4:3 format. A digital 4:3 format displayed on a 16:9 screen leaves black bars on both sides of the picture. Those black bars originate from the source (meaning the broadcast TV station you are watching or the cable channel you are watching). You will not be able to stretch the picture yourself using your TV controls. If you have a cable or satellite box, there is typically an option to stretch the 4:3 picture to fill the screen. If this is your case then the box itself is stretching the picture. Things will look out of shape, people will look fat and squatty, but it will fill your screen.
If you are watching an analog 4:3 format (which is what you have been watching for years until digital and HD came along), you will also see black bars but those originate from your TV, not from the source broadcaster. So you could stretch the picture yourself using your TV controls. Again at the cable or satellite box, if you subscribe to one of those, should also have options to override this and stretch the picture.
There is one more scenario; black bars (pillars) on the sides as well as along the top and bottom. Sometimes, those who produce programming or even commercials, use the letterbox black frame for special effect purposes. In these cases there is nothing wrong with your TV, the broadcaster, or anything else. But sometimes you will be watching your 4:3 analog TV or your 16:9 digital TV and you see black bars on all 4 sides of the picture. This happens because a television program is produced in high definition and is only being broadcast in high definition. It is not simulcast in standard definition. In addition to that, the program is being broadcast from a TV station that is not showing it directly from the network feed, it is being recorded and played back at a later time. And because most TV stations can not (yet) record and playback HD programming (as we discussed) they can only broadcast this HD programming in non-HD format. That's why you'll get black bars on the top, bottom, and both sides of your picture. If you have a digital TV and can zoom in, you will be able to get rid of them, but the picture quality will suffer severely. The program, at this point, will most likely be in 480i or 480p which is not conducive to zooming; the picture will look grainy and blurry.
The moral of this story: Sometimes the picture doesn't look right; and just because the picture takes up the whole screen doesn't mean its High Definition.
Stay tuned for more.
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