Security mark with chroma-based encoding

A system for printing a secure document, comprising:

• a processor;
• a printing device;
• a computer-readable medium containing programming instructions that, when executed by the processor, cause the processor to:
• identify secure content to print on a substrate within a security mark;
• identify a first color and a size or spatial frequency for the secure content;
• identify a second color for a background of the security mark, wherein the background corresponds to portions of the security mark where the secure content will not be printed, and wherein the first color and the second color will together exhibit a chrominance variation that is not visible to the unaided human eye or when viewed with the assistance of a magnifying glass, but will be visible when the secure content will be viewed with the assistance of a microscope;
• identify a first set of instructions for printing a document containing the security mark;
• and
• form the document by applying the security mark to a substrate so that the security mark comprises:
• a background contained within a border, wherein the background exhibits the first color, and
• a foreground contained within the border, wherein the foreground exhibits the second color and contains the security mark printed according to the identified size or spatial frequency.

A system for printing a secure document, comprising:

• a processor;
• a printing device;
• a computer-readable medium containing programming instructions that, when executed by the processor, cause the processor to:
• identify microtext to print on a substrate within a security mark;
• identify a first color and a size or spatial frequency for the microtext;
• identify a second color for a background of the security mark, wherein:
• the background corresponds to portions of the security mark where the microtext will not be printed,
• the first color and the second color will together exhibit a chrominance variation that is not visible to the unaided human eye or when viewed with the assistance of a magnifying glass, but will be visible when the microtext will be viewed with the assistance of a microscope, and
• the first color and the second color exhibit a luminance variation that is at least a factor of ten less than the chrominance variation and not visible to the unaided human eye or when viewed with the assistance of a magnifying glass, but that is visible when viewed with the assistance of a microscope;
• identify a first set of instructions for printing a document containing the security mark;
• and
• form the document by applying the security mark to a substrate so that the security mark comprises:
• a background contained within a border, wherein the background exhibits the first color, and
• a foreground contained within the border, wherein the foreground exhibits the second color and contains the security mark printed according to the identified size or spatial frequency.