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An adaptive image authentication scheme f or vector quantization compressed image

An adaptive image authentication scheme f or vector quantization compressed image. Authors: Jun-Chou Chuang , Yu-Chen Hu Source: Journal of Visual Communication and Image Representation, Volume 22, Issue 5, July 2011, Pages 440-449 Speaker: Lu Wan-Yu Date: 2011/01/05. Outline.

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An adaptive image authentication scheme f or vector quantization compressed image

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  1. An adaptive image authentication scheme for vector quantization compressed image • Authors: Jun-Chou Chuang , Yu-Chen Hu • Source:Journal of Visual Communication and Image Representation, Volume 22, Issue 5, July 2011, Pages 440-449 • Speaker: Lu Wan-YuDate: 2011/01/05

  2. Outline • Introduction • Related work- Vector quantization (VQ) • Proposed method- Embedding phase- Authentication code generation and embedding- Temper detecting phase • Experimental results • Conclusions

  3. Introduction • The protection of the digital images becomes more and more important because they can be easily copied and modified. • The image authentication schemes can be generally classified into two categories: - signature-based schemes - fragile watermark-based schemes

  4. Related work (1/3) • Vector quantization (VQ) – Codebook generation 0 1 2 . . . N-1 Training Images Codebook

  5. Related work (2/3) • Vector quantization (VQ) – Encoding Original Image Index table Codebook

  6. Related work (3/3) • Vector quantization (VQ) – Decoding VQCoded Image Index table Codebook

  7. Proposed method (1/8) • Embedding phase Step 1: Determine block size. (m x m) m=2 m=1 m=1 m=2 Index table (partial)1x1index block Index table (partial)2x2index block

  8. Proposed method (2/8) • Embedding phase Step 2: Determine the number of embeddable indices. (1≤ino≤mm) Step 3: Decide the indices used for embedding according to . The indices with number 1, (1 + disp), (1 + 2 x disp), . . . EX1. m x m = 2 x 2 = 4disp = 4 / 2 = 2 1, 1+2=3 EX2. m x m = 2 x 2 = 4disp = 4 / 3 = 1 1, 1+1=2, 1+2x1=3

  9. Proposed method (3/8) • Embedding phase m=2 m=1 m=2 m=1 Index table (partial)1x1index block Index table (partial)2x2index block ino=1 ino=2

  10. Proposed method (4/8) • Embedding phase 0 1 2 . . . N-1 Codebook

  11. Proposed method (5/8) • Authentication code generation and embedding Step 1: Use a PRNG to generate tnib x ino random. Step2: q = rvmod 2eb Step3: r = x mod 2eb ex. eb = 1 (embed 1 bit to each embeddable index) rv: 87 →　01 01 0 1 1 1 q x: 10 →　00 00 1 0 1 0r

  12. Proposed method (6/8) • Authentication code generation and embedding tnib= 4 (4 blocks)ino = 2 (2 embeddable index in each block)tnib x ino= 4 x 2 = 8 random values m=2 rv:87, 40, 52, 25, 47, 63, 28, 96x :10, 35, 22, 19, 33, 30, 21, 19 q  10 011100r 010 1 1011 m=2 Index table (partial)

  13. Proposed method (7/8) • Temper detecting phase • Receiver need to know: random number seed, m, ino, eb m=2 m=2 Watermarked index table (partial) rv:87, 40, 52, 25, 47, 63, 28, 96x :11, 35, 22, 19, 33, 29, 22, 20 q  10011100ac 11011100

  14. Proposed method (8/8) • Temper detecting phase

  15. Experimental results (1/7)

  16. Experimental results (2/7)

  17. Experimental results (3/7)

  18. Experimental results (4/7)

  19. Experimental results (5/7)

  20. Experimental results (6/7)

  21. Experimental results (7/7)

  22. Conclusions • Embedded image quality v.s. detection accuracy. • It is suggested that the number of embedded bits for each selected index should be set to 2 when the size of the index block is set to 2x2 in the proposed scheme.

  23. Thanks for your attention!

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