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Reversible data hiding based on block truncation coding scheme

Reversible data hiding based on block truncation coding scheme. Outline. Introduction Related works Block truncation coding (BTC) Reversible data hiding Proposed method Embedding process Extraction process Experimental results Conclusions. Introduction.

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Reversible data hiding based on block truncation coding scheme

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  1. Reversible data hiding based on block truncation coding scheme

  2. Outline • Introduction • Related works • Block truncation coding (BTC) • Reversible data hiding • Proposed method • Embedding process • Extraction process • Experimental results • Conclusions

  3. Introduction • Data hiding is referred to as a process to hide some information data into cover media. • The data hiding schemes can be generally classified into two categories: - Irreversible data hiding - Reversible data hiding

  4. Related works - BTC (1/2) • Moment preserving block truncation coding (MPBTC) 動量保留區塊截短碼 (90, 146, (1110100011101100)2) 16bits Original gray level image Bit pattern MPBTCreconstruct image Reconstruct level (a, b): Source: Delp, E. J., and Mitcell, O. R. “Image Compression Using Block Truncation Coding,” IEEE Transactions on Communications(27:9), pp. 1335-1342,1979.

  5. Related works - BTC (1/2) • Absolute moment block truncation coding (AMBTC) 動量絕對值區塊截短碼 (92, 144, (1110100011101100)2) 16bits Original gray level image Bit pattern AMBTCreconstruct image Reconstruct level (a, b): Source: Lema, M. D., and Mitchell, O. “Absolute Moment Block Truncation Coding and Its Application to Color Image,” IEEE Transactions on Communications (32:10), pp. 1148-1157, 1984.

  6. Related works – reversible data hiding (1/6) • Histogram shifting • Step1: Generate image histogram (P) Histogram (Z) Original gray image Histogram of Lena image Source: Zhicheng Ni, Yun-Qing Shi, NirwanAnsari, and Wei Su, “Reversible Data Hiding”, IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY(16:3), 2006.

  7. Related works – reversible data hiding (2/6) • Step2: To shift the pixels of histogram • If P>Z → To shift the range of the histogram , [Z+1, P-1], to the left-hand side by 1 unit. • If P<Z → To shift the range of the histogram , [P+1, Z-1], to the right-hand side by 1 unit. • ------------------------------------------------------------------------------------- • Step3: To hide the secret data by pixels P • If P>Z → To be embedded bit is “1”, the pixel value is changedto P-1. If the bit is ”0”, the pixel value remains. • If P<Z → To be embedded bit is “1”, the pixel value is changedto P+1. If the bit is ”0”, the pixel value remains.

  8. Related works – reversible data hiding (3/6) Original image Peak point Zero point P=3, Z=6and P<Z shift to right-hand [3+1,6-1] 4 → 5 5 → 6

  9. Related works – reversible data hiding (4/6) Secret bits: 1 1 0 0 1 1 0 1 Using P=3, 0 → 3 1→ 4 Marked image

  10. Related works – reversible data hiding (5/6) P=3 Z=6 Extracted secret bits: 1 1 0 0 1 1 0 1 extract 3→0 4→ 1 Marked image 6→ 5 5 → 4 4→ 33→ 3 recover Original image

  11. Related works – reversible data hiding (6/6) • Multiple pairs Example of 2 pairs. Original image P2 P1 Z1 Z2

  12. Proposed method (1/4) • 藏入機密資料到AMBTC後的壓縮碼中。 • 本方法結合AMBTC和直條圖位移技術。

  13. Proposed method (2/4) • Embedding process AMBTC Test image Compressed image 1) Image size: 512x512 2) Block size: 4x4 3) Vectormnum:16384 4) Compressed codes: 16384 trios of (ai, bi, BMi).

  14. Proposed method (3/4) • Embedding process • 重建階 ai蒐集起來產生A={a1, a2, a3, …, ak}。 • 重建階 bi 蒐集起來產生B ={b1, b2, b3, …, bk}。 • 利用公式 di= bi - ai計算兩個重建階之間的差值。 • 重建階di蒐集起來產生D ={d1, d2, d3, …, dk}。 • 針對D做直條圖位移將機密資料藏入產生d'i。 • 利用公式a'i= bi- d'i產生a'i。 • 針對B做直條圖位移將機密資料藏入產生b'i。 • 壓縮碼(a'i, b'i, BM)傳送給接收端。

  15. Proposed method (4/4) • Extraction process • 利用D和B的兩個直方圖找出的峰點與零點、影像尺寸與區塊大小。 (必要訊息) • 針對B，利用b'i的值判斷是否有被藏入，有則從b'i取出。 • 取出機密資料後則可位移還原回bi。 • 利用公式a'i= bi - d'i推回d'i 。 • 針對D，利用d'i的值判斷是否有被藏入，有則從d'i取出。 • 取出機密資料後則可位移還原回di 。 • 利用公式 di = bi - ai推回ai 。 • 透過壓縮碼(ai, bi, BM)將影像區塊重建。

  16. Experimental results (1/7) • Eight grayscale test images of 512x512 pixels (a) Airplane (b) Girl (c) Baboon (d) Lenna (e) Toys (f) Pepper (g) Boat (h) Sailboat

  17. Experimental results (2/7) • PSNR of MPBTC and AMBTC

  18. Experimental results (3/7) • Comparative method

  19. Experimental results (4/7) • Comparative method

  20. Experimental results (5/7) • Propose method

  21. Experimental results (6/7) • Propose method

  22. Experimental results (7/7) • Capacity of Comparative method and Proposed method PNO=2 Comparativemethod (a) (b) (c) (d) (e) (f) (g) (h)

  23. Conclusions • 本方法在藏入機密資料壓縮後的影像重建品質非常接近原先利用絕對動量保留區塊截短碼壓縮後的影像重建品質，且又能擁有不錯的藏量。 • 藏完機密資料後的壓縮碼仍保有與絕對動量保留區塊截短碼相同的壓縮碼形式。 • 無資料量擴張的問題。 • 可回復式資料隱藏。 • 保障機密資料的安全性。

  24. Thanks for your attention!

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