Embedding frequency modulation infrared watermark in digital document

摘要

Embodiments are disclosed for generating an infrared mark indicator comprised of security information in a printed image. Image data is rendered to a CMYK image. A black plane of the CMYK image is separated and transformed to a frequency domain wherein the frequency components are alternated to encode the watermarking message. The CMY values are selected based on the encoded black value in order to maintain a same color appearance image for the printed image under a normal visual light illuminant. The image data is printed on the substrate in accordance with the transformed planes wherein upon the resultant printed image being exposed to infrared illuminant, a print pattern is detectable as an infrared mark when scanned with an infrared sensing device.