Patent ID: 6700991
Filing Date: 2004-03-02
Classification: G06T

Abstract:
A method of embedding hidden digital watermarks in images, comprising the steps of:(a) providing an original image and a watermark image, wherein the watermark image, wherein the watermark image is a binary image with visually recognizable patterns; (b) applying pseudo-random permutations to the watermark image for generating a dispersed watermark image; (c) applying block-based permutations to both the original image and the dispersed watermark image to form a plurality of original image blocks each with a corresponding dispersed water mark block according to a variance value of each original image block and an information amount of each dispersed watermark block; (d) applying FDCT (Forward Discrete Cosine Transform) on each of the original image blocks independently so that each of the original image blocks is transformed into a DCT coefficient block; (e) embedding the correspond dispersed watermark blocks into the DCT coefficient blocks corresponding to a predetermined frequency range to form a plurality of combined DCT coefficient blocks; and (f) applying IDCT (Inverse Discrete Cosine Transform) to the combined DCT coefficient blocks to form an embedded watermark image.