Why do some HD channels still display those unsightly black bars on the side of the screen? If you're receiving HD over-the-air signals on a HDTV, shouldn't it fill the whole TV screen?
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.