Patent ID: 8111432

Claim:
A method for infrared watermarking using modified gray component replacement/undercolor removal schemes comprising: implementing a low infrared absorption gamut color conversion strategy yielding an original low infrared absorption gamut, wherein said low infrared absorption gamut color conversion strategy includes utilizing relatively low amounts of black toner comprising high carbon amounts; implementing a high infrared absorption color conversion strategy yielding an original high infrared absorption gamut, wherein said high infrared absorption gamut color conversion strategy includes utilizing relatively high amounts of black toner comprising high carbon amounts computing a boundary by combining the original low infrared absorption gamut with the original high absorption gamut; creating a new low infrared absorption gamut and a new high infrared absorption gamut that each include a similar shape defined by the boundary providing new high and low infrared absorption transforms using the new high and low absorption gamuts and using the new high and low infrared absorption transforms for providing an output color mixture, wherein the similar shaped new high and low absorption gamuts are used for color matching such that a watermark and an image are visible as a similar color under a first light source and as a different color under a second light source.