A method and a device for processing an image to be displayed with a reduced number n of color components are disclosed. The method comprises, for at least one of the color components, a reduction operation that is carried out by means of a dynamic round off dependent on the position (x, y) of the pixel to display. Thus, in a very simple way, image processing preventing the occurrence of artifacts, flickering or other flaws that the reduction of the number of colors would inevitably produce, can be realized.