WATERMARK DETECTION

摘要

A method of detecting a watermark embedded in a rotated video field is disclosed. The method entails correlating two video tiles in the rotated video field to find relative positions of a watermark. An estimation of an angle of rotation of the video field is performed based on the relative positions of the watermark. The angle of rotation in the rotated video field is estimated by selecting a pair of video tiles, determining a magnitude of a shift in one tile of the pair relative to the other, and calculating the angle of rotation based on the magnituded of the shift and a pre-known width of the video tiles. An expected watermark pattern is then rotated by the estimated angle of rotation, and the roated expected watermark pattern is used as input to a Symmetric Phase Only Match Filter (SPOMF) system for watermark detection.