We introduce a method for combining the covert encoding of data in hardcopy using a steganographic halftone with the extraction of a microscopic print signature from around the outside of the halftone suitable for forensic levels of authentication. Outline models for the extracting a unique forensic signature include the input image, the edge-refined reference halftone, and scans of sample stegatones. The results for recovery of several printed samples are reported. An example with a 3mm character can reliably carry 32 bits of data and carry a forensic signature with a false positive rate of 7×10−21.
Robert Ulichney, Stephen Pollard, Matthew Gaubatz, Steven Simske, "Combined Covert Data Embedding and Forensic Markings for Graphic Objects" in Proc. IS&T Int'l Conf. on Digital Printing Technologies and Digital Fabrication (NIP28), 2012, pp 364 - 367, https://doi.org/10.2352/ISSN.2169-4451.2012.28.1.art00025_2