The model number isn't posted, however some models have a way to do this, others do not, and you can check either the manual or the menu options. If it is possible, it will be under the Screen Burn Protection menu, under the SETUP menu to change grey levels.
The plasma units do this to avoid image retention and screen burn-in. The recommendation if you are able to turn them off is not to. While it may prove to be distracting, the design is to prolong the use of your panel and protect the panel from image retention.
I have a Samsung 42-inch flat panel tv. When viewing with the 4:3 aspect ratio, there are wide and bright white vertical bars (filling in the space normally used by the picture image in a 16:9 ratio) on both sides of the 4:3 display making it difficult to watch a television show using that aspect ratio. Is there any way to change the white to black? thanks.