Patent ID: 7330560

Claim:
A method of inserting a multiple bit message in an image, characterized in that it comprises the steps of: selecting a predetermined number of points in the image as a function of predetermined criteria, so as to form a coordinate system in the image, calculating an affine transformation between a predetermined coordinate system and the coordinate system formed in the image, generating a pseudo-random sequence for each symbol of the multiple bit message to be inserted, in the predetermined coordinate system, projecting each pseudo-random sequence into the coordinate system formed in the image, by affine transformation, and inserting each symbol of the multiple bit message to be inserted, as a function of its respective projected pseudo-random sequence; wherein said selecting comprises detecting a first set of interest points, the first set comprising a first number of points, the interest points being ordered, selecting the points of the coordinate system formed in the image, among the points of interest, the coordinate system comprising a second number of points less than or equal to the first number of points, verifying that the points of the coordinate system formed in the image are the first interest points in the order, and if the response is negative, modifying the image around the points of the coordinate system formed in the image, such that an additional detection of a second set of interest points, the second set comprising the second number of points, provides the points of the coordinate system formed in the image.