Patent ID: 6952484

Claim:
A method of detecting a predetermined mark embedded in an image, said mark comprising a predetermined arrangement of a plurality of elements, said elements having a predetermined colour characteristic, the method comprising the steps of: processing the image to provide an encoded representation of the image at a predetermined resolution, said encoded representation being adapted to emphasize the elements of the mark based on the predetermined color characteristics of the elements; detecting a location of each of said elements of the mark embedded in the image from the encoded representation; applying a mask having a predefined annular region to said mark to convert those detected element locations that fall within said annular region into a set of spatial features representing an angular distribution of the detected elements of said mark; comparing the converted set of spatial features to a known set of spatial features to provide a confidence level measure representing a correlation error between the spatial features of the known set and the determined set of spatial features; and detecting said predetermined mark on the basis of said confidence level measure.