Method for computing an exposure pattern for exposing a desired pattern on a target in a charged-particle multi-beam processing apparatus, in which a particle beam (lb, 50) is directed to and illuminates a pattern definition device comprising an aperture array composed of a plurality of blanking apertures (24, 33, 43) through which said particle beam (pb) penetrates for writing said desired pattern by exposing a multitude of pixels (px) within an image area on the target, wherein in the pattern definition device said plurality of blanking apertures (24, 33, 43) is arranged in a predetermined arrangement defining mutual positions of the blanking apertures, each blanking aperture being selectively adjustable with regard to a dose value to be exposed through the respective blanking aperture onto a corresponding aperture image generated on the target during a respective exposure interval, said dose value taking a respective value selected from a discrete gray scale, wherein during a writing process of said desired pattern, a sequence of exposure intervals is made, wherein in each exposure interval the blanking apertures are imaged onto the target, thus generating a corresponding plurality of aperture images (b1, bi0, bi1) to expose pixels in accordance with said desired pattern, wherein the method comprises: i) providing the desired pattern as a graphical representation (72, 106) on the image area on the target, said graphical representation (72, 106) having a predetermined width of resolution, said width being larger than a nominal distance between neighboring positions of the pixels within said image area, ii) providing a convolution kernel (89', 121), said kernel describing a mapping from an element of the graphical representation to a group of pixels, said group of pixels being centered around a nominal position of said element, and iii) calculating a nominal exposure pattern as a pixel raster graphics (ps) defined on the multitude of pixels, by convolution of the graphical representation (72, 106) with the convolution kernel (89', 121), said nominal exposure pattern being suitable to create a nominal dose distribution on the target, wherein the convolution kernel is configured to adjust a critical dimension along at least one direction in the image area on the target for compensating a deviation of the imaging from the pattern definition device to the target, the convolution kernel being configured to degrade a point spreading function of said imaging to emulate an intensity distribution in a specific region within the beam array field having an increased blur. wherein in the pattern definition device said plurality of blanking apertures (24, 33, 43) is arranged in a predetermined arrangement defining mutual positions of the blanking apertures, each blanking aperture being selectively adjustable with regard to a dose value to be exposed through the respective blanking aperture onto a corresponding aperture image generated on the target during a respective exposure interval, said dose value taking a respective value selected from a discrete gray scale, wherein during a writing process of said desired pattern, a sequence of exposure intervals is made, wherein in each exposure interval the blanking apertures are imaged onto the target, thus generating a corresponding plurality of aperture images (b1, bi0, bi1) to expose pixels in accordance with said desired pattern, wherein the method comprises: i) providing the desired pattern as a graphical representation (72, 106) on the image area on the target, said graphical representation (72, 106) having a predetermined width of resolution, said width being larger than a nominal distance between neighboring positions of the pixels within said image area, ii) providing a convolution kernel (89', 121), said kernel describing a mapping from an element of the graphical representation to a group of pixels, said group of pixels being centered around a nominal position of said element, and iii) calculating a nominal exposure pattern as a pixel raster graphics (ps) defined on the multitude of pixels, by convolution of the graphical representation (72, 106) with the convolution kernel (89', 121), said nominal exposure pattern being suitable to create a nominal dose distribution on the target, i) providing the desired pattern as a graphical representation (72, 106) on the image area on the target, said graphical representation (72, 106) having a predetermined width of resolution, said width being larger than a nominal distance between neighboring positions of the pixels within said image area, ii) providing a convolution kernel (89', 121), said kernel describing a mapping from an element of the graphical representation to a group of pixels, said group of pixels being centered around a nominal position of said element, and iii) calculating a nominal exposure pattern as a pixel raster graphics (ps) defined on the multitude of pixels, by convolution of the graphical representation (72, 106) with the convolution kernel (89', 121), said nominal exposure pattern being suitable to create a nominal dose distribution on the target,