Abstract: As a surface having an apparent grey level is obtained by activating a certain proportion of pixels of this surface, the screen is virtually divided into blocks of pixels all having the same dimensions and a set of patterns each representing a block is defined in advance for each desired apparent grey level, while the different patterns of one and the same set all have the same proportion of active pixels, for example two out of sixteen for a grey level of 2/16 in the scale ranging from white to black (20-27) but a different arrangement of inactive pixels and active pixels, and for the display of each pixel of the image a pattern of the set corresponding to the desired grey level is selected, and the pixel is displayed in the active or inactive state of the dot having the same position in the selected pattern. A different pattern (from 20 to 27) is chosen at each redefinition of an image.