I have an Insignia 32" NS-RTV32 SDTV which has a 16:9 mode for HD content and the component input. I understand that some TVs use this mode to "compress" the 480 scan lines into a 16:9 picture (thereby using all of the available scanlines when viewing widescreen content). I was wondering if anyone knew if the Insignia compresses the scanlines, or just simply draws the black bars on top and bottom. Is there any way of telling?

Turn the brightness up. If the black bars turn gray, then they are still being drawn.

I've tried this and it doesn't look like the black bars change in brightness. Is this a definitive test?

Well, try using a dark scene. If the blacks in the frame turn gray and the letterboxing doesn't turn gray, then that's pretty much a guarantee that the TV is compressing.

In that case, it looks like the TV is compressing. Thanks for the help.