•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.

•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

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

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).

◦ 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

•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…

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

•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.

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.

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.

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.

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.

a)host image b)watermark bit

c)Watermarked image

Difference image

Extracted watermark

original image

Watermarked image

Original imageDifference image between watermarked image and original image

Imperceptibility 

Robustness

HIGH SECURITY

HIGH CAPACITY

•Not full proof

•Reduces social sharing

• Promotes negative image of you

Copyright watermarking Data hiding watermarking Broadcast watermarking Integrity watermarking

•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.

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.

  [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.