If you notice that the picture quality has changed on your 50-inch LG Plasma high definition television set, it may just be that the lighting in your room has changed or that the image source (either a TV antenna, cable or satellite TV box, or DVD or Blu-ray movie) looks different. It could, however, be a sign of something far more serious. If you want to get to the root of any picture discrepancies and diagnose any issues you're having with your 50-inch LG Plasma HDTV, you'll need to do a few tests.
Make sure any external devices that you're trying to use are properly connected to your 50" LG Plasma HDTV. If you are experiencing sound or picture trouble, first eliminate everything but the TV as a possible source of the problem. Double-check your cable connections and make sure everything is plugged in correctly. If you're playing a DVD or Blu-ray disc, make sure the disc is clean and free of dirt. If the problems persist, you are having a problem with the TV and not one of your external devices.
Press the "Picture" button on the LG Plasma HDTV's remote control. This will adjust the shape of the picture being displayed on screen. LG Plasma HDTVs have multiple picture modes for use depending on the aspect ratio of the program you're watching as well as your personal preference, so any issues you're having with an oddly formatted picture may be a result of the TV being on the wrong "Picture" setting.
Press "Menu" on the LG HDTV's remote control and adjust the picture quality settings. These include brightness, contrast and colour settings. Adjust against a regular television program and try to make the skin tone of the people on screen match the skin tone of someone in real life. If you adjust these settings and still continue to experience an odd-looking picture, something may be wrong with the colour components or back light in your LG Plasma HDTV.
Flip through the channels to many different programs. If the problem that you're having persists, it is a problem with the LG Plasma TV. If the problem is only present on that one specific channel, you are having a problem with the channel and there is nothing you can do to fix it. For example, if you flip through the channels and a series of blue or black dots appears on screen in the same positions in every channel, you have dead pixels in your screen that will need to be repaired by a licensed technician.