A compensation process for improving color saturation and image quality of a plasma display panel (PDP) is provided, wherein a brightness of light generated from each of red, green, and blue discharge cells of each pixel on said PDP is calculated through a numeric operation according to laws of color matching. The process comprises the step of increasing or decreasing the strength of input image signals of each of the red, green, and blue discharge cells in accordance with the calculation result for adjusting brightness of the generated red, green, and blue lights so as to subtract a visible light generated by gas in each of the red, green, and blue discharge cells during gas discharging, thereby eliminating an adverse effect of the visible light on color purity and color temperature of the PDP during gas discharging. This can obtain an image on PDP having an optimum color purity and color temperature and reduce the manufacturing cost.