The invention relates to a grid image consisting of one or several grid fields which respectively contain a grid pattern which influences electromagnetic radiation and which consists of a plurality of dashed grid lines. The dashed grid lines are characterized by the following parameters: orientation, curvature, distance and profile. According to the invention, a grid field (30) of said grid image, which can be recognized separately with the naked eye,contains a grid pattern which influences electromagnetic radiation and which is provided with dashed grid lines (32) for which at least one of the parameters (orientation, curvature, distance and profile) can vary (34) over the surface of the grid field. |