1 Self-Recovery Fragile Watermarking Scheme with Variable Watermark Payload Fan Chen, Hong-Jie He, Yaoran Huo, Hongxia Wang Southwest Jiaotong University, Chengdu, Sichuan, P.R. China

2 Fan Chen Chengdu, Sichuan, China Southwest Jiaotong University An associate professor, and pursuing the Ph.D degree Research interests: digital watermarking and Digital-forensics.

3 Presentation Outline 1.Background 2.Proposed Self-recovery Scheme 3.Experimental Results 4.Conclusions and Future Work Self-Recovery Fragile Watermarking Scheme with Variable Watermark Payload

4 1. Background Image Blocks Block codes ： 8×8 pixels: DCT coefficients 2×2 pixels : average intensity Common Characteristic The length of block codes is fixed.

Background SIP laboratory Examples: Smooth Rough Blocks DCT quantized coefficients [9]. Z.Qian et al, Image self-embedding with high-quaility restoration capability, Digital Signal Processing, 21 (2011):

Background SIP laboratory  Qian [9] proposed that the blocks were encoded to different number of bits.  The rougher blocks have more bits  And the smoother blocks have fewer bits. But, the amount of the compression code bits was still fixed for different images, no matter the image is smooth or rough. [9]. Z.Qian et al, Image self-embedding with high-quaility restoration capability, Digital Signal Processing, 21 (2011):

7 The watermark payload is more than the average length of the codes. This is due to the following two facts:  Tampering coincidence problem: Dual watermark [7], Reference Sharing Mechanism [2]  Tamper detection problem: Authentication data Increasing watermark payload Decreasing the quality of watermarked image Being vulnerable to the collage attack 1. Background

8 2 The Proposed Scheme  Main purpose  Reducing the watermark payload as much as possible while maintaining good recovery quality and security  Strategies  Variable watermark payload

9  Watermarked Image Generation  Variable-Length Block Coding  Variable-Payload Watermark embedding  Tamper Detection and Recovery  Tamper detection  Tamper recovery 2 The Proposed Scheme

10  Variable-Length Block Coding For a block of 8×8 pixels: The basic-code: 24 bit The total-code : the number of bits is variable 2 The Proposed Scheme -----watermarked Image Generation Type sType-code Code length v i (bits) Code length: (24+27,24+101)

11  Variable-Payload Watermark Insertion 1.Watermark payload equals to the length of block-codes. 2.Basic-code and total-code of a block are encrypted and hidden in the different blocks based on secret key. 2 The Proposed Scheme -----watermarked Image Generation

12 2 The Proposed Scheme -----Watermarked Image Generation Basic-code Total-code Basic-code: the second LSB of the last 24 pixels Total-code

13 SIP laboratory  Tamper Detection: Statistical Detection [5] (1) Basic-code mapping: T B (2) Total-code mapping : T T (3) Incorporation : T 2 The Proposed Scheme -----Watermarked Image Generation

14 SIP laboratory Basic-code matching Total-code matching Detection results T Tamper detection performance is better [5] He ea al, Adjacent-Block Based Statistical Detection Method for Self- Embedding Watermarking Techniques, The Proposed Scheme -----Watermarked Image Generation

15  Tamper Recovery : Only for the invalid blocks.  Watermark-reserved: the tampered block whose basic-code or total-code is valid  the corresponding codes  Watermark-destroyed: the tampered block whose basic-code and total-code are destroyed  the valid blocks adjacent to the block 2 The Proposed Scheme Tamper Detection and Recovery

16 3. Experimental results Images Watermark Payload (bpp) Proposed Qian[9] Invisibility (dB) Proposed Qian [9] Boat Lena Airplane Barbara Mona Lisa Elaine Goldhill Napoleon Man Fingerprint  The watermark payload and invisibility for different images

17  Restoration Performance The tampered image can be recovered by the proposed scheme with an acceptable visual quality even the tamper ratio is up to 60% of the host image. 3. Experimental results

18 (a) Watermarked Napoleon (b) Watermarked Mona Lisa  Collage attack 3. Experimental results both of size 372×288

19 (c) Tampered image (about 20%)  Collage attack (d) Proposed dB 3. Experimental results

20  multi-region and multi-attack tampering (1) General tampering (2) Only content tampering (3) Collage attack (4) Constant-feature attack 3. Experimental results

21 (a) Proposed 34.38dB (b) Qian [9] dB (c) He [5] dB 3. Experimental results Qian [9] and He [5] cannot resist all the counterfeiting attacks

22  Our work  A variable watermark payload  Invisibility  Recovery quality  Security 4. Conclusions and Future Work

23 4. Conclusions and Future Work  Future work  Extending this approach to resist mild distortion such as JPEG compression  And analytic investigation on the tamper detection performance.

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