Encoding signals with fluorescing inks

Abstract

The present disclosure relates to signal processing such as digital watermarking and other encoded signals. One claim recites a substrate comprising a plurality of first areas and a plurality of second areas, in which each of the plurality of first areas comprises a color ink printed therein with a UV topcoat layer printed over the color ink, in which the UV topcoat layer includes a material that absorbs at or around 350 nm and emits in the visible spectrum, and in which each of the plurality of second areas comprises the color ink printed therein, and in which the plurality of first areas is arranged on the substrate in a 2-dimensional pattern that is machine-readable from image data depicting the plurality of first areas, and in which the 2-dimensional pattern represents signal elements that cover only between 1-20% of an area on the substrate, and in which contrast in the image data between the plurality of first areas and the plurality second areas comprises a contrast difference in the range 75%>contrast difference>8%. Of course, other claims and combinations are provided in the specification with reference to specific implementations and related examples.

Dependencies are inferred from the claim text.