[1]

AN ANALYSIS OF DIGITAL WATERMARKING IN FREQUENCY

DOMAIN

Presented by

SRINIVAS KHARSADA PATNAIKROLL # EI200118043

Under the Guidance of

DR. SAROJ KUMAR MEHERFaculty in Electronics & Communication

Engineering

DIGITAL WATERMARKING[2]

Form of data hiding or steganography.

Hides the message, so cannot be seen.

Maintains privacy and protects data from other viewers like hackers.

It may include hiding of numbers, logo or signature in the form of signal, image or video.

REQUIREMENTS[3]

Perceptual transparency

Robustness

Security

Payload of watermark

Oblivious and non-oblivious

FREQUENCY DOMAIN WATERMARKING

[4]

First transformed to frequency domain.Low frequency components are modified

to contain text or signal. DCT DFT DWT STFT

BLOCK DIAGRAM REPRESENTATION

[5]

[6]Two techniques for embedding Additive multiplicative

I=original image, W=watermark, I’=watermarked image, a=scaling factor.

)**(' WIaII

DISCRETE COSINE TRANSFORM

[7]

Real domain transformRepresents image as coefficient of

different frequencies of cosines.Forms the basis of the JPEG image

compression algorithm. Watermark

detection embedding casting

DISCRETE FOURIER TRANSFORM

[8]

Translation invariant

Modulated DFT amplitude coefficients

Makes watermark image content

dependent

)),(1(|),(||),(| vuWkvuDFTvuWDFT

DISCRETE WAVELET TRANSFORM[9]

Used when a signal is being sampled like digital signal or image processing.

Provides sufficient information for both analysis and synthesis of signal.

Reduction in computation time.

Separates image into sub images

SHORT TIME FOURIER TRANSFORM

[10]

The signal is divided into small stationary segments.

Used to acquire frequency representation of the actual frames.

Precision determined by size of window.

Not a flexible approach.

APPLICATIONS[11]

Copyright protection

Fingerprinting

Copy protection

Broadcast monitoring

Indexing

Medical safety

CONCLUSION [12]

We can work for digital protection by the help of certain laws.

Time complexity of watermark signal can be enhanced by extending the length of watermark.

Can be used in any frequency domain that involves quantization and transformation.