1. A method of displaying gray scales in a plasma display panel having an inverse gamma correction unit that operates using gamma tables, comprising the steps of: (a) allowing the inverse gamma correction unit to match picture signals, which corresponds to an n number of frames (n is a natural number) respectively, to an n number of previously stored gamma tables; (b) allowing the inverse gamma correction unit to perform an inverse gamma process on the picture signals received according to the matched gamma tables to produce real gray scales every frame; and (c) allowing the inverse gamma correction unit to divide the real gray scales every frame by n and then to produce last real gray scales.