Certain examples described herein relate to the embedding a pattern in an output content having at least two-dimensions, for example a printed output. Content data having at least two dimensions is processed to generate an array of spatial elements, each spatial element corresponding to a respective location in the output content and comprising a probabilistic distribution for a set of output material compositions. A threshold matrix is generated using pattern data corresponding to a pattern, and the array of spatial elements is halftoned using the threshold matrix. The threshold matrix is generated such that the pattern is embedded in the output content.