Methods and apparatus of determining a halftone scheme are described. In an example, data representing a three-dimensional object is obtained, the data comprising object model data representing the geometry of the three-dimensional object and object property data representing at least one object property of at least a portion of the object. It is determined if a halftone scheme dependent object property is specified by the object property data and a halftone scheme is determined. Data representing a portion of the object having a halftone scheme dependent object property is associated with a determined halftone scheme.