Dgrooms2007 receives HD over-the-air signals on his HDTV. He asked the Answer Line forum why some HD channels still display those bars on the side.
This can be perplexing, especially when you press your remote's Info button and the on-screen display tells you you're watching a 16x9 720p or 1080i broadcast. But the reasons are actually pretty simple.
Just because a station is broadcasting in HD doesn't mean the show originated that way. When HD stations broadcast non-HD content, they usually pillarbox it, putting black bars on the side of the screen. That's the only way to screen 4:3 content on a 16:9 TV without either cropping or distorting the image.
If you really hate those bars, you could see if your TV has a way to zoom into the image to get rid of them. This option is usually available with a remote control button called Aspect, Format, P. Size, or something similar. You almost certainly won't have an option to stretch out the image, however, as you would with a real SD broadcast.
Or you could simply get used to the pillarboxing. After all, it gives you the picture as it was shot.
Read the original forum discussion at http://forums.pcworld.com/message/207329.
This story, "Why Do HD broadcasts on an HDTV Still Have Sidebars?" was originally published by PCWorld.