Why Do Black Bars Appear at the Sides of My Widescreen HDTV?

Written by Clearly Resolved
Thursday, 31 May 2007

[ Q ] I thought that HDTV was supposed to always be widescreen, but sometimes I see black bars on the sides my widescreen HDTV when I'm watching local HD television stations. Why?

And why can't I get rid of the black bars by using the "stretch" or "zoom" modes built into my HDTV?

[ A ] At this point in the transition to digital broadcasting, local stations are providing only a small portion of their daily broadcast schedule in the HD format. Whenever a local TV station broadcasts an analog, non-HD program, they simply convert the 4x3 analog program to 16x9 digital video and send it out over the digital channel.

This results in the 4x3 image filling the 16x9 screen from top to bottom, but with that 4x3 image centered horizontally, with black bars appearing at the sides. It's not obvious, but the black bars are actually part of the signal broadcast by the station.

The fact that the black bars are part of the picture transmitted by the digital station probably explains why you can't "stretch" or "zoom" the picture to eliminate them -- the 16x9 screen area is fully occupied, so there's no way to stretch the 4x3 image to cover what appears to be unused screen real estate (but isn't).

Some newer model HDTVs have added advanced "screen modes" that will allow the user to reduce or even eliminate the black bars that appear as part of these digital broadcasts.

80,00% of 5 voters found this FAQ useful, I found this FAQ

useful

not useful

< Prev		Next >