METHODS AND SYSTEMS FOR WATERMARK PROCESSING OF LINE ART IMAGES

Binary data is embedded in banknote artwork, permitting later recovery by, and control of, compliant devices that may encounter banknote image data, such as photocopiers, scanners, and printers. One embedding method involves providing nominal line art for the banknote, and imposing a virtual grid of points over the art, thereby defining plural regions. The luminance of at least certain of these regions is changed to effect encoding of the binary data. The luminance may be changed, e.g., by changing the width or spacing of the artwork lines, or by introducing new lines into the artwork.