An apparatus for creating a pattern on a workpiece sensitive to radiation, such as a photomask, a display panel or a microoptical device. The apparatus includes a radiation source, a spatial modulator (SLM) having a multitude of modulating elements (pixels), a projection system, an electronic data processing and delivery system controlling said modulator, a precision mechanical system for moving said workpiece and an electronic control system. Specifically, the drive signals can set the pixels in a number of states larger than two, and intermediate modulation states are used for pixels along edges of pattern features. The design of the modulating elements and the exposure method create, for differently placed and/or differently oriented edges in the pattern, a symmetry in the aperture stop of the projection system.