Method for including a double layer security mark in digital document data and document to be printed

摘要

A method and system are provided for including a double layer security mark in digital document data defining an image of a document to be printed and in the printed document, itself. A fluorescence mark region including a fluorescence mark is defined using first and second metameric colorant mixtures. Variation in colorant spatial coverage between the first and second metameric colorant mixtures results in colorant-free areas that define the fluorescence mark due to substrate fluorescence under UV illumination. The fluorescence mark region is modified to define a double layer fluorescence mark region including the fluorescence mark and also including at least one visible light object defined by a third colorant mixture. The third colorant mixture is added to the fluorescence mark region by masking the colorant-free areas of the fluorescence mark region to prevent writing of the third colorant mixture data to the colorant-free areas so as not to disturb the colorant-free areas.