High-Capacity Image Hiding Using Vector Quantization
This paper presents a novel method for hiding multiple secret images within a host image of the same size, utilizing vector quantization (VQ) to achieve high capacity. The proposed scheme allows for greater hiding capacity and incorporates a comprehensive index compression process, ensuring enhanced security through encryption using the DES cryptosystem. Experimental results demonstrate an average image quality gain of 1.304 dB, affirming its effectiveness. The scheme shows promise for secure data hiding applications while managing the balance between capacity and image fidelity.
High-Capacity Image Hiding Using Vector Quantization
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Presentation Transcript
High-capacity image hiding scheme based on vector quantization Authors: Yu-Chen Hu Source: Pattern Recognition, vol. 39, pp. 1715-1724, 2006 Speaker: Shu-Fen Chiou(邱淑芬) Date: 2006/10/19
Outline • Introduction • Proposed method • Experimental results • Conclusion • Comment
Introduction • This method is hiding multiple secret images into a host image of the same size. • The proposed scheme provides a higher hiding capacity.
Hiding bits sno: total number of secret images Nc: the size of VQ codebook k: the vector dimension rmax: The maximal number of modified bits
Training codebook Random seed rs Codebook is sorted by mean values of codewords
VQ Codebook 0 1 2 (20,45,…,76) 253 254 Original image Index table 255
AAD • Design HCT
Hiding s(i,j)=00 127+1 Host pixel h(i,j) HCT(i,j)=2 b(i,j)=127 mod 22=3 d(i,j)=0-3=-3 h’(i,j) d’(i,j)=-3+22=1 -22+1<=d(i,j) <-(22-1)/2=-1.5
Index compression Encode: ‘0’+’01’ RANG=4
Index compression Encode: ‘10’+’1’+’00110’
Index compression Encode: ‘11’+’10000000’
Encrypt • Compressed index table is encrypted by DES cryptosystem suing the secret key sk • W, h, sno, Nc, k, rs, pk, RANG, and ThDIST are encrypted by DES cryptosystem also using the same secret key sk
The secret extraction procedure • Extract w, h, sno, Nc, two random seeds key rsand pk, RANG, THDIFFanddeterminermax. • Generate the VQ codebook with Nc codeword using H' with random seed rs. • Obtain a serial of random number by pk. • To rebuild the original index table by RANGandTHDIFF.
Experimental results Comparative storage cost (unit: bits) of the proposed scheme (PS) and the proposed scheme without index compression (PS').
Experimental results Provide an average of 1.304dB image quality gain.
Experimental results Image qualities of the stego-images of the proposed scheme
Experimental results 1024 codebook
Conclusion • A novel image hiding scheme based on vector quantization is proposed. • The proposed scheme is secure.
Comments • 用VQ將secret images壓縮，所以secret images取出後會失真。 • 將index table再壓縮，隱藏數量變少。
