When watching a television program in widescreen (with black bars at the top and bottom of the screen), the black level of the bars change as the scenes' contrast changes (ie, sometimes the bar will look deep black, other times a gray colour).

I can get into the service menu for this television fine with [mute] [1,8,2] [power].

Does anyone know what item in the service menu might be able to help for it? I can't find any definitions for the items on the net and I don't think I should mess around with it without knowing.