A Restricted Regionbased Datahiding Scheme Chair Professor ChinChen
A Restricted Region-based Datahiding Scheme Chair Professor Chin-Chen Chang Feng Chia University National Chung Cheng University National Tsing Hua University http: //msn. iecs. fcu. edu. tw/~ccc
Outline u Introduction u Proposed scheme u Experimental results u Conclusions 2
Introduction (1/3) • Traditional information hiding Secret Message: 110110110011 (Cover Image) (Stego Image) 3
Introduction (2/3) 001100 10 001111 01 010011 10 010110 10 010111 01 011001 00 010111 11 110010 11 101011 11 000111 10 100101 10 101100 Secret Message: 110110110011 11 00 00 01 00111101 00111110 01001111 01011000 01011111 01100100 01011111 11001011 10101111 00011110 10010110011 10111100 10011100 01011001 50 60 61 78 90 93 100 95 203 175 30 150 179 188 156 89 (cover pixels) (binary 101111 representation of cover pixels) 100111 010110 (binary representation of stego pixels) 4
Introduction (3/3) • Our proposed scheme Secret Message: 110110110011 Protected Region (Cover Image) (Stego Image) 5
Embedding 1. Select protected regions 2. Generate a location map 3. Compress the location map with Huffman coding 4. Embed the information 6
Select Protected Regions 50 60 61 78 90 93 100 95 203 175 30 150 179 188 156 89 Protected region 7
Generate a Location Map 1 changeable pixel 0 unchangeable pixel 50 60 61 78 1 1 90 93 100 95 1 1 203 175 30 150 1 1 0 0 179 188 156 89 0 0 Location map 8
• Generate Tokens • Get the tokens Type 1: Type 2: Type 3: Type 4: 1 1 1 1 1 0 0 0 Token Frequency 1111 1 1 2 000000 1 0… 01 (ending with 1) 1111 (eight 1 s) single 1 00… 00(ending with 0) 9
• Get the Huffman Code Token root 0 Frequency codeword 1111 1 00 1 2 1 000000 1 01 1 1 2 0 1111 1 000000 • Get a condensed location map Location map: 11111000000 Condensed location map: 001101 10
• Header: Ex. 1: Cover pixel: 01100101 11100111 10 1 0110 11100111 Condensed Huffman code: Stego pixel: 1: embedded 0: unembedded Header: 10 11
• Header: Ex. 2: Cover pixel: 01100101 11100111 Huffman code: 10 10 0110 11100110 Stego pixel: 1: embedded 0: unembedded Header: 11 12
• Payload: Header Huffman code Secret information Header: 11 Huffman code: 001101 Secret information: 110110110011 Payload: 11 • 001101 • 110110110011 13
Ex 1: Huffman code (Condensed location map): 001101 The size of condensed location map = 6 (bits) Number of needed 1+ =4 changeable pixels For header For condensed location map 1 4 2 3 1 1 0 1 1 1 1 0 0 0 (Location map) Private Key: 11011 14
Ex 2: Huffman code (Condensed location map): 001101 The size of condensed location map = 6 (bits) Number of needed 1+ =4 changeable pixels For header For condensed location map 1 2 3 4 1 1 1 1 1 0 0 0 (Location map) Private Key: 1111 15
50 60 61 78 90 93 100 95 203 175 30 150 179 188 156 89 (cover pixels) 001100 10 001111 01 010011 10 010110 10 010111 01 011001 00 010111 11 110010 11 101011 11 000111 10 100101 10 11 00 00 01 (binary representation of cover pixels) 101100 101111 100111 010110 Payload: 11 • 001101 • 110110110011 Private key: 1111 00111100 00111111 01001101 51 60 63 77 01011011 01011101 0110 01011111 91 93 102 95 11001000 10101111 00011110 10010110 203 175 30 150 10110011 10111100 10011100 01011001 179 188 156 89 (binary representation of stego pixels) (stego pixels) 16
Experimental Results 512 X 512 = 262144 (bits) Changeable and unchangeable region Information (512 X 512) 39972 39822 Private key (bits) 21601 19911 Hiding capacity (bits) 382306 377944 PSNR (d. B) 45. 0783 45. 1281 Private key (bits) 13324 13274 Hiding capacity (bits) 593445 582826 PSNR (d. B) 38. 8685 38. 8996 Huffman code (bits) Two LSBs Three LSBs Unchangeable region (white) 17
Conclusions • Simple and efficient • Hiding capacity is large • Good stego image quality 18
- Slides: 18