The present invention relates generally to digital watermarking. In one embodiment, a method of detecting copying of a printed object is provided. In another embodiment, a method is provided to measure digital watermark strength. In yet another embodiment, and for printing applications, an embedded digital watermark may be used to carry printer information that is later decoded by a watermark decoder and used to examine a digital scan of a printed object and determine whether the printed object is authentic. Other embodiments are provided as well.