Plasma TVs typically have excellent screen uniformity. However a plasma TV’s screen uniformity is affected by various factors, the most significant being the quality of the glass panel, and the way in which the phosphors are aged. The precise terms for specific television faults vary from source to source.
Banding, also called false contouring or posterization, refers to unrealistic solid strips of color in areas that should display a smooth transition. Vertical banding is usually used to describe specifically the vertical banding issues on LCD displays.
Effects of banding
Banding affects TV images when they display a gradual change between shades of a single color. One of the clearest examples of this is footage of the sky in which the blue goes from light blue at the bottom to dark blue at the top. When banding occurs, the transition isn’t smooth and that section of the picture appears to be broken into bands, each of a solid shade.
The most common explanation for banding lies in the way individual TV sets combine red, green and blue light in different proportions to produce colors. In some cases, the problem may be that the source material contains more shades of color than the screen can handle. It’s caused by a difficulty in controlling the vertically controlled arrays of LCD pixels and keeping them all at the same voltages, etc. It will vary from display to display, and is usually most visible on green, which causes itself to be seen on smooth images especially skies and the like. In other cases, the TV may use techniques to create a wider range of shades of colors. Sometimes, this involves creating shades beyond the colors contained in the source material; such techniques aren’t always effective. In both cases, the result is that a visibly large band of pixels that ideally would be in different shades instead displayed in strips of uniform solid colors.
So if you notice such bands on your TV screen, check the manufacturer’s booklet for permissible limits of banding or schedule a technician visit to have it checked.