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Pattern-based Data Hiding for Binary Image Authentication by Connectivity-preserving

Huijuan Yang, Alex C. Kot , IEEE Fellow IEEE Transactions on Multimedia, Vol. 9, No. 3, Apr. 2007 Multimedia Security Final Project R97922062 葉容瑜 R97922003 程瀚平. Pattern-based Data Hiding for Binary Image Authentication by Connectivity-preserving. Introduction Proposed Method

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Pattern-based Data Hiding for Binary Image Authentication by Connectivity-preserving

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  1. HuijuanYang,AlexC.Kot,IEEEFellow IEEETransactionsonMultimedia,Vol.9,No.3,Apr.2007 Multimedia Security Final Project R97922062 葉容瑜 R97922003 程瀚平 Pattern-based Data Hiding for Binary Image Authentication by Connectivity-preserving

  2. Introduction • ProposedMethod • TheAuthenticationMechanism • ExperimentalResults • Conclusions

  3. Introduction(1/3) • Digital documents • Ex. certificates, digital books, fax, personal documents • Howto ensure the authenticity and integrity of digital documents,as well as detection of tampering and forgery, become a seriousconcern • Powerful image editing software • Data hiding for binary images authenticationhas been a promising approach to alleviate these concerns

  4. Introduction(2/3) • Data hiding on binary images can be done • the lower level: flipping pixels from black to white and vice versa • the higher level: modifying width of strokes and spacings between characters and words • In this paper, our focus is on data hiding for binary images in lower level for the purpose of image authentication

  5. Introduction(3/3) • Define a “connectivity-preserving” criterion to assessthe “flippability” of a pixel • Connectivity among pixels plays an importantrole to their visual qualities

  6. The Main Objectives • Assess the “flippability” of a pixel using the connectivity-preserving criterion to achieve good visual quality of the watermarked image • Handle the “uneven embeddability” of the image by adaptively embedding the watermark only in those “embeddable” blocks • Study the invariant features in flipping pixels in binary images to achieve blind watermark extraction • Explore different ways of partitioning the image to achieve larger capacity • Investigate on how to locate the “embeddable” pixels in the watermarked image so as to incorporate cryptographic signature to achieve higher security

  7. Introduction • ProposedMethod • FlippabilityDecision • BlockPartition • Embeddability • Capacities • WatermarkEmbeddingandExtraction • TheAuthenticationMechanism • ExperimentalResults • Conclusions

  8. Flippability Decision • Flippability • The transitions from the pixel to its eight neighbors in a 3 * 3 block • In particular, the 4- and 8-connectivity among pixels • VH Transition • IR Transition • C Transition

  9. VH Transition • Nvw:the number of uniform white transitions along vertical and horizontal directions • Nvb: the number of uniform black transitions along vertical and horizontal directions Nvw = 0, Nvb = 2 Nvw = 0, Nvb = 0 Black: 1 White: 0 => Nvw = 0, Nvb = 0 => Nvw = 0, Nvb = 0

  10. IR Transition • Nir: the number of the interior right angle transitions Nir = 0 Nir = 0 => Nir = 1 => Nir = 0 Black: 1 White: 0

  11. C Transition • Nc: the number of transitions from the center pixel to the sharp corners Nc = 1 Nc = 0 => Nc = 0 => Nc = 0 Black: 1 White: 0

  12. Flippability/Connectivity-Preserving Criterion • Flippable • VH transition, IR transition, and C transitionremain the same before and after flipping the center pixel • Flip the pixel will not • Destroy the connectivity b/w pixels in the neighborhood(VH) • Create extra clusters as well(IR) • Destroy the 8-connectivity among pixels(C) • By satisfying the “Connectivity-Preserving” criterion, the local connectivity is preserved

  13. BlockPartition • Several different types of blocks • Fixed 3*3 block (FB) • Non-interlaced block (NIB) • Interlaced block (IB)

  14. Embeddability • Determined pixels • Non-interlaced block scheme:all pixels except the boundary pixels • Interlaced block scheme:all pixels except those lie in the sharing rows and columns • The embeddability of a block depends on the “flippability” of the determined pixels in the block

  15. Capacities • Only one pixel is flipped in each block => The prob. of a pixel to be “flippable” in a block is independent to other pixels • Assume the probability that a pixel satisfies the “Flippability Criterion” is p • FB: The prob. of each block to be “embeddable” is p • NIB: The prob. is 1 – (1-p)^(n-2)2 • IB: The prob. is 1 – (1-p)^(n-2)2 • A larger block size definitely will increase the prob.for a block to be “embeddable”, however, the total number of blocks will be decreased =>Decrease the capacities

  16. WatermarkEmbedding • Partition the image into equal size square blocks, note that the block size does not need to be square • Determine the flippability of the determined pixels based on the “Flippability Criterion” • Once a pixel is identified as “flippable”, the block is marked as “embeddable”. The current “flippable” pixel is identified as the “embeddable” pixel, i.e., “embeddable” location of the block • Proceed to the next block • Repeat steps 2 to 4 until all the blocks are processed • Embed the watermark in the “embeddable” blocks by flipping the “embeddable” pixels (if needed) to enforce the odd-even feature of the number of black or white pixels in the block

  17. Embeddable pixels = flippable pixels • Flipping a pixel in a block may affect • the “flippability” of the pixels in the same block • but notthe pixels in its neighboring blocks • The “embeddability” of a block is invariant in the watermark embedding process • The “flippability” of a pixel is invariant in the watermark embedding process • A “flippable” pixel which is identified as “embeddable” is still “flippable,” hence an “embeddable” block remains “embeddable” • The watermark can be extracted blindly fromthe “embeddable” blocks by computing the odd-even feature ofthe number of black or white pixels

  18. Introduction • ProposedMethod • TheAuthenticationMechanism • Locate“Embeddable”PixelsCriterion • AuthenticationProcess • TheVerificationProcess • ExperimentalResults • Conclusions

  19. Locate“Embeddable”PixelsCriterion • The odd-even enforcement is employed for the watermark embedding • Vulnerable to the “parity attack” Ex: an adversary can carefully flip two pixels in the same block while keeping the odd-even feature of the block unchanged.

  20. Locate“Embeddable”PixelsCriterion • p-4 condition • Flipping the pixel that does not change the “flippability” of its previous four (p-4) neighbors that lie in the same 3 x 3 block • d-2 condition • Flipping the pixel that does not affect the “embeddability” of those d-2 pixels (determined pixel) that have already been processed in the same block

  21. Locate“Embeddable”PixelsCriterion

  22. AuthenticationProcess

  23. TheVerificationProcess

  24. Introduction • ProposedMethod • TheAuthenticationMechanism • ExperimentalResults • CapacityandVisibility • TestLocatingEmbeddablePixelsCriterionandAuthenticationMechanism • Comparisons • Conclusions

  25. CapacityandVisibility

  26. CapacityandVisibility

  27. CapacityandVisibility The original text image of size 336 x 336 (Chinese) (d) Hide 482 bits by FB 3 x 3 (e) Hide 733 bits by NIB 4 x 4 (f) Hide 1261 bits by IB 4 x 4

  28. CapacityandVisibility (b) The original text image of size 336 x 336 (English) (g) Hide 447 bits by FB 3 x 3 (h) Hide 672 bits by NIB 4 x 4 (i) Hide 1237 bits by IB 4 x 4

  29. CapacityandVisibility (b) The original text image of size 336 x 336 (Handwritten) (g) Hide 313 bits by FB 3 x 3 (h) Hide 554 bits by NIB 4 x 4 (i) Hide 972 bits by IB 4 x 4

  30. CapacityandVisibility • Evaluate the visual distortion caused by flipping pixels • The visual distortion table proposed by Wu et al. is employed. M. Wu and B. Liu, “Data hiding In binary images for authentication and annotation,” IEEE Trans. Multimedia, vol. 6, no. 4, pp. 528–538, Aug. 2004.

  31. CapacityandVisibility • Distortion score (DS) • Total distortion (TD) • Average per pixel distortion (APPD)

  32. CapacityandVisibility

  33. TestLocatingEmbeddablePixelsCriterionandAuthenticationMechanismTestLocatingEmbeddablePixelsCriterionandAuthenticationMechanism The original image of size 920 x 230 (b) Hide 1056 bits by proposed algorithm with FB 3 x 3 (c) The watermarked image that is tampered (d) The original logo image (e) The reconstructed logo image when no tampering occurs (f) The reconstructed logo image when the watermarked image has been tampered

  34. Comparisons Original image of size 173 x 115 (b) The proposed method (c) Wu et al. method (d) Tseng et al. (e) Lu et al. (f) Yang & Kot 111 bits 180 bits 260 bits

  35. Introduction • ProposedMethod • TheAuthenticationMechanism • ExperimentalResults • Conclusions

  36. Conclusions • A novel blind data hiding scheme for binary images authentication based on connectivity-preserving • A window of 3 x 3 is employed to access the “flippablility” of a pixel in a block • Different types and sizes of block can be chosen cater for different applications • The proposed scheme can be applied to a wide variety of binary image authentication

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