Abstract: A multi-gray-scale image display method and apparatus for displaying a multi-gray-scale image on a PDP by diffusing, as an error, a part of gray scale data representing an input image requiring more than a gray scale resolution of the PDP to a target pixel from different adjacent pixels in a scanning direction according to a diffusion factor corresponding to each pixel. A determination is made whether the target pixel to which the error is diffused from the adjacent pixels is positioned in an upper line of the whole image represented by the data. The diffusion factor is set such that it determines the error diffused from an adjacent pixel differently when the target pixel to which the error is diffused from the adjacent pixel is positioned in the upper line of the whole image.