an image display method and system for a plasma display panel . an image of each field displayed on the plasma display panel corresponding to input image signals is divided into sub - fields . weighting values of the sub - fields are combined to display grays . the sub - fields are divided into three continuous groups . sub - fields corresponding to a least significant bit and a lsb + 1 of each sub - field data are included in a second sub - field , which is positioned in a middle of the three consecutive groups with respect to time . therefore , a time difference between the lsb and the lsb + 1 of the sub - field data with respect to images displayed by 50 hz phase alternating by line image signals is reduced such that contour noise between low gray regions is diminished .