Certain examples described herein relate to the processing of object data corresponding to a three-dimensional object. First data corresponding to a first portion of the three-dimensional object and second data corresponding to a second portion of the three-dimensional object, separate from the first portion, are determined. The first data is halftoned using a first halftoning technique to generate control instructions for an apparatus to produce the first portion of the three-dimensional object. The second data is halftoned using a second halftoning technique to generate control instructions for the apparatus to produce the second portion of the three-dimensional object.