1. A method for reducing dynamic false contour on a plasma display, executed by the plasma display, comprising: determining a grayscale phase of a current pixel of the plasma display; changing the grayscale phase of the current pixel if one of N pixels in the same row before the current pixel has the same grayscale value and the same grayscale phase as those of the current pixel, wherein N is an integer equal to or greater than 2; and outputting the current pixel on the plasma display.