Phase locked IR encoding for peened 2D barcodes

A method to decode a printed 2D barcode, comprising:

• deriving at least one colorant combination of an image and at least one colorant combination for dots within a 2D barcode on a document, where the at least one colorant combination of the image and the dots of the 2D barcode form a metameric pair;
• printing the image and the 2D barcode onto a document;
• exposing the 2D barcode to a particular bandwidth light source with a spectral power distribution that maximizes the visual distinction between the image and the dots of the 2D barcode;
• and
• utilizing said visible narrow band illumination to decode the exposed 2D barcode generated from the image.

A method for generating a printed 2D barcode, comprising:

• selecting at least one CMYK colorant pattern for printing that includes a comparatively strong black component;
• deriving a second CMYK colorant pattern, which does not include a black component or only a comparatively weak black component, with the property of appearing substantially similar to the first pattern under broadband illumination, but distinct from the first pattern under a selected bandwidth illumination;
• and
• printing the two colorant patterns in close spatial proximity to produce a 2D barcode that is concealed under broadband illumination and revealed under the selected bandwidth illumination, the first and second colorant patterns are printed via a zero degree fill structure and a matching frequency and phase.