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AN ANALYSIS OF DIGITAL WATERMARKING IN FREQUENCY

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AN ANALYSIS OF  DIGITAL WATERMARKING IN FREQUENCY Powered By Docstoc
					DIGITAL WATERMARKING

    AN ANALYSIS OF DIGITAL
  WATERMARKING IN FREQUENCY
           DOMAIN
                       Presented by
        SRINIVAS KHARSADA PATNAIK
             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
Payload of watermark
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
      Additive
      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
Copyright protection
Fingerprinting
Copy protection
Broadcast monitoring
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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posted:9/6/2011
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