to temporarily store the pixel data for the writing process the distortion correction according to several embodiments of the invention can be done either prior to rasterization fig1 a or after rasterization fig1 b fig1 a shows a flowchart 120 of the datapath for the case when the distortion correction is done prior to rasterization the datapath starts upon being supplied a pattern to be exposed 121 presented e g as a vector data file stage 122 the exposure area is segmented into smaller areas in a preferred realization of the invention these areas are small or of about the same size in comparison to the area of the beam array field of the multi bream writer corrections that can be applied in the vector domain e g proximity effect correction may be carried out to all chunks independently possibly in parallel and the resulting data is sorted and coded in a way to improve computation speed of the following steps the output is a collection of chunks where all chunks contain a collection of geometries stage 123 the pattern to be exposed is prepared for distortion corrected according to one of the above variants a b or c each of the variants comprises a step where particular features or point coordinates of the pattern to be exposed are assigned to a respective segment of the exposure area in particular variants b and c comprise a step where the pattern to be exposed is divided into smaller features stage 124 next the distortion correction is performed separately for each segment in accordance with certain embodiments of the invention these corrections may include parameters such as scaling sx 01 sy 01 in both spatial directions x and y a rotation r 01 an angle.