a method of gloss correction in a process of printing a three - dimensional object , wherein a print head is moved in two directions parallel to a substrate to slicewise apply material building the object up to a height as defined in a height map , comprising the steps of : deriving , from the height map , a normal map which assigns to any point of the object surface a normal vector that is normal to the surface of the object ; segmenting the surface points into at least two regions in which the normal vectors of points in the region fulfill a predefined similarity criterion that is related to a surface gloss of the object ; for each region , estimating an expected surface gloss value of the object ; calculating a gloss correction map based on a difference between the estimated surface gloss values for said at least two regions ; and applying to the object a surface treatment in accordance with the gloss correction map .