PRINTED AUTHENTICATION FOR LOW RESOLUTION REPRODUCTIONS

摘要

A document includes an authenticity-indicating feature configured such that a reproduction of the document renders the printed feature visually distinctive from an original rendering of the document. The printed feature includes printed elements arranged on the substrate in a latent image region and a background region. The printed elements in the latent image region include a plurality of regularly spaced printed shapes arranged with a spatial frequency less than about 50 per inch. The printed elements are printed with a carbon-based ink, toner, or dye, and separated from one another by contrasting regions that do not include the carbon-based ink, toner, or dye. The printed elements in the background region are at least partially surrounded by the latent image region such that, in the original rendering of the document, the plurality of regularly spaced printed shapes is not readily distinguishable from the background.