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Reversible Data Hiding ——a technical review - 14th Information

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Reversible Data Hiding ——a technical review - 14th Information Powered By Docstoc
					Capacity-Approaching Codes for Reversible
              Data Hiding

      Weiming Zhang, Biao Chen, and Nenghai Yu

   Department of Electrical Engineering & Information Science
        University of Science and Technology of China




              Information Hiding Conference 2011
                         Introduction
 What is reversible data hiding?
     The original cover can be losslessly restored after the
     embedded information is extracted.


message                              data extraction     message
             data
                          stego             &
  cover    embedding
                                    cover restoration    cover




                                                                 2
                       Introduction
What is reversible data hiding?
   The original cover can be losslessly restored after the
   embedded information is extracted.
Why is reversible data hiding needed?
   In some applications, even any degradation of the
   original cover is not allowed, such as medical imagery,
   military imagery and law forensics.

Where is reversible data hiding applied?
   Media annotation;
   integrity authentication ...


                                                             3
                     Introduction
How to do reversible data hiding?




 Type-I: Binary feature sequence, generic compression
 method (e.g., arithmetic coder);

 Type-II: Integer operations: Difference Expansion (DE) or
 Histogram Shifting (HS)— specific compression manner for
 the histogram
                                                             4
                       Introduction
Type-I: Basic model [Kalker]



  d modifications




  Embedding rate:

   Distortion:

How to maximize embedding rate under any given distortion?

                    A rate-distortion problem
                                                         5
                   Introduction
Theoretical upper bound [Kalker]




                                    6
                      Introduction

Recursive Code construction [Kalker]
  Key idea:
    the marked cover can be used to reconstruct the cover




                    H ( x1 )        H ( x1 | y1 )
                                                            7
                  Two observations

Observation I
  Not only the marked cover can be used to reconstruct the
  cover, but also the reconstructed cover can help to extract
  message.




                                                                8
                  Two observations

Observation II




                                     9
                   Two observations
Observation II
 The maximum capacity is achieved at D=p0-1/2;
  When D≤p0-1/2, the optimal embedding manner is that
 only 0’s are allowed to be changed. (Corollary 1 of Theorem 2,
 [Kalker])

Our strategy:
    Only embed data into 0’s and skip 1’s;
    At the decoder side, the embedding positions can be
    recognized with the help of reconstructed cover.




                                                            10
       How to embed data into all-zero cover

RZL coding (reverse zero-run length) [Wong]
  Message is divided into disjoint segments of k bits, each of which
  is converted to a integer d∈[0,2k-1]; skip d zeros in the cover,
  and flip the (d+1)th zero.

Our method: improve RZL by the idea of ZZW construction
  A construction consists of two layers:
  The outer layer: only embed one bit;
  The inner layer: when embedding bit “1” in the outer layer,
  embed another k bits with RZL; otherwise skip 2k zeros.


                                                                 11
       How to embed data into all-zero cover
Example: k = 2




                                               12
How to embed data into all-zero cover




                                        13
              Proposed method
Improved recursive construction

Improved coding for all-zero cover




       x1 :           0       1

       y1:        0       1   1
                                     14
                   Proposed method
Example 2 (follows Example 1)




                                     15
    Comparison: Embedding efficiency vs. embedding rate
Embedding efficiency e is defined as number of bits embedded
by unit distortion, i.e. e=ρ/Δ=L/d.




                                                           16
Comparison: Embedding efficiency vs. embedding rate




                                                      17
           Improving Type-I Schemes
      (embedding in binary feature sequences)
1. Improving RS method for spatial images [Fridrich]


 Texture
 complexity of
 pixel blocks is
 used to construct
 binary feature
 sequence.




                                                       18
              Improving Type-I Schemes
1. Improving RS scheme for spatial images [Fridrich]




                                                       19
              Improving Type-I Schemes
2. Improving the scheme for JPEG images [Fridrich]



  quantized DCT
  coefficients
  with value 0
  and 1 are used
  as binary feature
  sequence.




                                                     20
              Improving Type-I Schemes
2. Improving the scheme for JPEG images [Fridrich]




                                                     21
                 Improving Type-I Schemes
3. Improving PS scheme for binary images [Ho]

                                                Test images
  Patterns of 4-
  length vector in
  difference image are
  used as binary
  sequence.




 Y.-A. Ho, et al., ``High capacity reversible data hiding in binary images using
 pattern substitution,” Computer Standards and Interfaces, 2009.
                                                                             22
        Improving Type-I Schemes
3. Improving PS scheme for binary images




                                           23
        Improving Type-I Schemes
3. Improving PS scheme for binary images
 Embed 260 bits




     (a) Marked by PS             (b) Marked by improved PS
                                                         24
             Improving Type-II Scheme
Improving HS-based scheme for spatial images [Luo]




 The proposed codes is used at the second embedding stage.
 Extension by embedding with two bins.




 L. X. Luo, et al., ``Reversible Image Watermarking Using Interpolation
 Technique," IEEE Trans. Inf. Forensics and Security, 2010.
                                                                          25
        Improving Type-II Schemes
3. Improving HS-based scheme for spatial images




    (a) Lenna




                                                  26
        Improving Type-II Schemes
3. Improving HS-based scheme for spatial images




 (b) Baboon




                                                  27
        Improving Type-II Schemes
3. Improving HS-based scheme for spatial images




 (c) Boat




                                                  28
Conclusion:
   • An improved coding method for all-zero cover
   • An improved recursive construction
   • A reversible data hiding method for binary cover



Future work:
    Integer-domain reversible data hiding




                                                        29
Thank you for your attention!




                                30

				
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posted:11/20/2012
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