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Hiding Data in a Color Palette Image with Hybrid Strategies

Hiding Data in a Color Palette Image with Hybrid Strategies. (to appear in Imaging Science Journal, 2008) Chair Professor Chin-Chen Chang Feng Chia University Tsing Hua University Chung Cheng University http://msn.iecs.fcu.edu.tw/~ccc. Outline. Introduction The proposed scheme

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Hiding Data in a Color Palette Image with Hybrid Strategies

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  1. Hiding Data in a Color Palette Image with Hybrid Strategies (to appear in Imaging Science Journal, 2008) Chair Professor Chin-Chen Chang Feng Chia University Tsing Hua University Chung Cheng University http://msn.iecs.fcu.edu.tw/~ccc

  2. Outline • Introduction • The proposed scheme • Experimental results • Conclusions

  3. Receiver Reconstructed Image Compression code 1000011010… Secret data: 011 Introduction • Information Hiding Sender Compression Code: 1000011010… Host Image Secret data: 011

  4. Palette Image • Color-Palette Image Color Palette

  5. The proposed scheme (1/11) • Luminance-sorted Palette Red pixel value Blue pixel value Luminance value Green pixel value

  6. The proposed scheme (2/11) • Luminance-sorted Palette

  7. PU= (RU, GU, BU) = (6, 9, 7) = (9, 9, 10) PL= (RL, GL, BL) = (12, 10, 13) The Reference Vector: X：original pixel value predicted pixel value The proposed scheme (3/11)

  8. The proposed scheme (4/11)

  9. Tradition Method Ex: Encoding Original Pixels Index Table The size of index table is 4×16 4 bits to encode a pixel. Color Palette

  10. = (9, 9, 10) Best codeword Prediction Method (1/2) X6 = (8, 10, 11) Color palette Original Pixels

  11. Distortion = 02+12+12 = 2 Threshold T If (Distortion < 10) encode it with state palette Else encode it with tradition method Insert indicator Use 5 bits to encode this pixel Use 3 bits to encode this pixel Prediction Method (2/2) X6 = (8, 10, 11) K2 = (8, 11, 12) K Index Table Index Table The size of index table is 3×8 + 5× 8

  12. The proposed scheme (5/11)

  13. Assume that the secret data is 001 If Distortion (K0, Original Pixel X) < thresholdT 4 Output: 1  indicator 100  compression code This is, output (1, 4) ≡ (1, 100) Else if Distortion (K0, Original Pixel X) > thresholdT Use sorted color palette to embed secret data (Phase-2 data embedding) The Proposed Scheme (6/11) Phase-1 data embedding K

  14. If D(X', P12)<D(X', P7) Indicator: 0 Secret data: 0 Output (0, 7) ≡ (0, 0111) Secret data: 1 Output (0, 12) ≡ (0, 1100) Else if D(X', P12)>D(X', P7) Indicator: 0 Secret data: 0 Output (0, 0, 12) ≡ (0, 0000, 1100) Secret data: 1 Output (0, 15, 12) ≡ (0, 1111, 1100) The Proposed Scheme (7/11) Phase-2 data embedding X= (8, 10, 11) P X’s best codeword

  15. The Proposed Scheme (8/11) Extracting Procedure

  16. ∵4>3 ∴ Decode with K0 The retrieved secret data is 001 The Proposed Scheme (9/11) Ex: (indicator, compression code) = (1, 100) Phase-1 extracting policy K

  17. The Proposed Scheme (10/11) Ex: (indicator, compression code) = (0, 0000, 1100) Phase-2 extracting policy P Secret data is 0 Decoded pixel with P12

  18. The Proposed Scheme (11/11) Ex: (indicator, compression code) = (0, 0111) Phase-2 extracting policy P If D(X', P12)<D(X', P7) Decode the pixel with P12 andretrieve secret data 1 Else Decode the pixel with P7 andretrieve secret data 0

  19. PSNR: 35.422 dB Hiding capacity: 304 Kb Experimental results (1/3) The color host images with size 512 × 512 Lena Pepper Baboon Three stego-images for threshold T=20 PSNR: 33.005 dB PSNR: 30.827 dB Hiding capacity: 271Kb Hiding capacity: 257 Kb

  20. Experimental results (2/3)

  21. Experimental results (3/3)

  22. Conclusions • A novel scheme is proposed to hide large amount of secret data into a color image. • The qualities of the reconstructed images are good.

  23. Thank you so much!

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