This document describes the development of a watermarking algorithm utilizing DCT and spread spectrum communications to ensure robustness against JPEG compression and other attacks. It covers the principles of digital image processing, the role of MATLAB in implementing these techniques, and the importance of imperceptibility, robustness, and security in watermarking. Additionally, it outlines the algorithm steps for embedding and extracting watermarks, emphasizing the low-frequency nature of the proposed scheme for enhanced resilience against image manipulations.

2. •In this application our aim is to develop a watermarking
algorithm based on DCT and Spread spectrum communications.
•To provide highly robust with respect jpeg compression and
also other common attacks whenever they are applied to
watermarked image.
•To provide higher imperceptibility is gained by scattering the
watermark’s bit in different blocks.

3. •The digital image processing deals with developing a digital
system that performs operation on digital images.
•It is a subfield of signals and system but focus particularly on
images.
•The input of that system is a digital image &the system process
that image using efficient algorithms gives an image as an output.
•Ex:adobe Photoshop

4.  Matlab is a high performance language for technical
computing.
 Matlab is a software package developed by Math-
Works, Inc.
 It has a wide applications in signals and system, image
&video processing.
 Matlab contains five types of windows:
 Command window, current directory, editor
window,workspace,command history

5.  Version:matlab 7.8.0.347(R2009a)
 MATLAB is an interpreted language (making it for the
most part slower than a compiled language such as C+
+).
 MATLAB is designed for scientific computation and is
not suitable for some things (such as parsing text).

6. ◦ Data hiding
◦ Making the information imperceptible
◦ E.g. watermarking
◦ Keeping the existence of information secret
 Water marking
1. visible-----copy right protection
2. Fragile ---Authentication, security

7. •This technique is proposed to protect copyright of digital
multimedia data.
•Water marking is one of the data hiding technique for security
purpose.
•Watermarking is an important mechanism applied to physical
objects like bills, papers, garment labels, product packing…

8.  Imperceptibility
◦ The modifications caused by watermark embedding should be below the perceptible
threshold
 Robustness
◦ - The ability of the watermark to resist distortion introduced by standard or malicious data
processing
 Security
◦ - A watermark is secure if knowing the algorithms for embedding and extracting does not
help unauthorized party to detect or remove the watermark

9. •DCT splits up the image into frequency bands, similar to discrete
Fourier transform, it transforms a signal or image from the spatial
domain to the frequency domain.

10.  The DCT is a widely used transformation in
transformation for data compression.
 The DCT is fast. It can be quickly calculated and is
best for images with smooth edges like Photos with
human subjects.
 DCT transform is a pretty good technique for image
compression. Correctly use the Advantage that provide
by DCT is the key to achieve good result while keep a
good Compression ratio.

11.  A narrow band signal is transmitted over a much larger
bandwidth such that, the signal energy present in any
single frequency is imperceptible.
 It transmits a narrowband signal over a much larger
bandwidth.
 The signal energy present in any single frequency is
un-detectable.

13.  1. Compute BDCT of host image,
 2. Create LRAI,
 3. Compute BDCT of LRAI,
 4. Embed each bit of Watermark, as a
 pseudo-random noise sequence into FH
 coefficients of each 8x8 block of transformed
 LRAI using (1),
 5. Compute IBDCT of watermarked LRAI,
 6. Replace the watermarked DC coefficients with
 the original ones in LRAI,
 7. Compute IBDCT of LRAI.

15.  1. Denoise watermarked image,
 2. Calculate difference image by subtracting denoised image
from watermarked image,
 3. Do steps from 1 through 3 from the embedding algorithm
for difference image,
 4. Compute the correlation between each block of transformed
LRAI. And both noise patterns for one and zero bits,
 Choose the noise pattern with higher correlation related to the
extracted watermark bit,
 Compute the average correlation coefficient overall extracted
watermark bits, and then compare it with a pre defined
threshold. The watermark is considered to be present if the
average correlation coefficient is greater than threshold.

16. a)host image b)watermark
bit
c)Watermarked image

17. Difference image
Extracted
watermark
original image

18. Watermarked imageOriginal image
Difference image between
watermarked image and
original image

19.  Imperceptibility
 Robustness
 HIGH SECURITY
 HIGH CAPACITY

20. •Not full proof
•Reduces social sharing
• Promotes negative image of you

21.  Copyright watermarking
 Data hiding watermarking
 Broadcast watermarking
 Integrity watermarking

22. •The watermark embedding scheme can be extended to
included encrypted watermarks.
•Watermark extraction algorithm can be extended to perform
water mark validation automatically.
• Suitable feature extraction and matching techniques have to
be explored.

23.  In this project, we proposed a DCT-based blind
watermarking scheme based on spread spectrum
communications.
 The low frequency nature of the proposed algorithm
makes the embedded watermark very robust to
common image manipulations such as filtering, scaling,
compression and malicious attacking.

24.
 [1] Lu C.-S., "Multimedia Security: Steganography and Digital
Watermarking Techniques for Protection of Intellectual Property", Idea
Group Publishing, 2005, ISBN: 1-59140-192-5.
 [2] Katzenbeisser S. and Petitcolas A.-P., "Information Hiding
Techniques for Steganography and Digital Watermarking," Artech
House, January 2000, ISBN: 1580530354.
 [3] Voloshynovskiy S. and Deguillaume F., "Information-Theoretic
Data-Hiding: Recent
 Achievements And Open Problems", International Journal of Image
and Graphics, Vol. 5, No.1,p.5–36, 2005
 [4] P. Meerwald, A. Uhl, “A Survey of Wavelet-Domain Watermarking
Algorithms”, EI San Jose, CA, USA, 2001
 [5] Cox I. J., Miller M. L., "The First 50 years of Electronic
Watermarking", Journal of Applied Signal Processing, vol.2, Issue 2, p.
126, 2002.