; AN ANALYSIS OF DIGITAL WATERMARKING IN FREQUENCY
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# AN ANALYSIS OF DIGITAL WATERMARKING IN FREQUENCY

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```									DIGITAL WATERMARKING

AN ANALYSIS OF DIGITAL
WATERMARKING IN FREQUENCY
DOMAIN
Presented by
ROLL # EI200118043

Under the Guidance of
DR. SAROJ KUMAR MEHER
Faculty in Electronics & Communication Engineering

SRINIVAS KHARSADA PATNAIK                               [1]
DIGITAL WATERMARKING

DIGITAL WATERMARKING
 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.

SRINIVAS KHARSADA PATNAIK                            [2]
DIGITAL WATERMARKING

REQUIREMENTS

Perceptual transparency
Robustness
Security
Oblivious and non-oblivious

SRINIVAS KHARSADA PATNAIK      [3]
DIGITAL WATERMARKING

FREQUENCY DOMAIN
WATERMARKING
First transformed to frequency domain.
Low frequency components are modified to
contain text or signal.
DCT
DFT
DWT
STFT

SRINIVAS KHARSADA PATNAIK                   [4]
DIGITAL WATERMARKING

BLOCK DIAGRAM
REPRESENTATION

SRINIVAS KHARSADA PATNAIK   [5]
DIGITAL WATERMARKING

Two techniques for embedding
   multiplicative
I=original image, W=watermark,
I’=watermarked image, a=scaling factor.

I '  I  (a * I * W )
SRINIVAS KHARSADA PATNAIK                  [6]
DIGITAL WATERMARKING

DISCRETE COSINE
TRANSFORM
 Real domain transform
 Represents image as coefficient of different
frequencies of cosines.
 Forms the basis of the JPEG image compression
algorithm.
 Watermark
   detection
   embedding
   casting

SRINIVAS KHARSADA PATNAIK                         [7]
DIGITAL WATERMARKING

DISCRETE FOURIER
TRANSFORM
Translation invariant
Modulated DFT amplitude coefficients

| WDFT (u, v) || DFT(u, v) | (1  k  W (u, v))

Makes watermark image content dependent

SRINIVAS KHARSADA PATNAIK                    [8]
DIGITAL WATERMARKING

DISCRETE WAVELET
TRANSFORM
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

SRINIVAS KHARSADA PATNAIK                   [9]
DIGITAL WATERMARKING

SHORT TIME FOURIER
TRANSFORM
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.

SRINIVAS KHARSADA PATNAIK                      [10]
DIGITAL WATERMARKING

APPLICATIONS
Fingerprinting
Copy protection
Indexing
Medical safety

SRINIVAS KHARSADA PATNAIK   [11]
DIGITAL WATERMARKING

CONCLUSION
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.

SRINIVAS KHARSADA PATNAIK                    [12]

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