2. Authors :
Ingemar J.Cox – Senior Member IEEE
Joe Kilian – Member IEEE
F.Thomson Leighton – Member IEEE
Talal Shamoon – Member IEEE
IEEE TRANSATIONS ON IMAGE PROCESSING , VOL 6 - DECEMBER 1997
3. INTRODUCTION
This paper presents a secure algorithm for
watermarking images, and a methodology for digital
watermarking that may be generalized to audio, video
and multimedia data. A watermark should be
constructed as an independent and identically
distributed Gussain random vector that is imperceptibly
inserted in a spread spectrum like fashion into the
perceptually most significant spectral components of
data. It argue that insertion of a watermark under this
rule makes the watermark robust to signal processing
operations and common geometric transformation
provided that the original image is available and it can
be successfully registered against the transform image.
4. SPREAD SPECTRUM WATERMARK
The problem: how to insert watermark into
most perceptually significant region of
spectrum in a reliability protective manner.
To solve: this problem, frequency domain of
the image or sound at hand is viewed as
communication channel, and the mark is
viewed as a signal that is transmitted through
it
5. SECURE SPREAD SPECTRUM WATERMARKS
FOR MULTIMEDIA
Spread spectrum watermark based on DCT
In order for a watermark to be robust, it
needs to be placed in the most significant
part of the image.
The watermark will be composed of random
numbers drawn from a Gaussian N(0,1)
distribution
Inserting the watermark to the image.
Inverse DCT
