DEVICE AND METHOD FOR ADAPTING A MASK IMAGE

The invention relates to a method for adapting a mask image with mask regions (110) to a digital image, comprising a selection of a boundary point (300), determination of one planar element Sa from a number of given examples and an enlargement or reduction of the mask region (110) to give an adapted mask image. The mask image is defined by a edge curve (130) and the digital image has a first region (10) with a first tone value type and a second region (20) with a second tone value type. The mask image is overlaid on the digital image and the edge curve (130) shall run along a contour curve (30) separating the first region (10) from the second region (20). The boundary point (300) is on the edge curve (130) of the mask which includes planar elements comprising planar elements of the first toner value type and planar elements of the second toner value type, such that the given planar element Sk(i) forms an extreme target function by placement thereof at an edge of the boundary point (300), wherein the target function depends on the planar fraction of that planar element on placement thereof at the position of the boundary point (300) which overlaps the first region (10) should the planar element be of the first toner value type and on the planar fraction of the planar element on placement thereof at the position of the boundary point (300) which overlaps the second region if the planar element is of the second toner value type. The enlargement or reduction of the mask region (110) is achieved about the given planar element Sk(i) dependent on the toner value type of the given planar element Sk(i).