A method of embedding data in a printed output having at least two-dimensions is described in which content data for the printed output and data to be embedded in the printed output are obtained. An input property value for a content element from the content data is determined. This is used to determine an output value for a probabilistic distribution of a set of output material compositions for a spatial element of the printed output, corresponding to the content element, based on the data to be embedded and the input property value.