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Palette Partition Based Data Hiding for Color Images Yu-Chiang Li, Piyu Tsai, Chih-Hung Lin, Hsiu-Lien Yeh, and Chien-Ting Huang Speaker : Yu-Chiang Li Date : 2009/09/13 Outline 1 Introduction 2 Related Work 3 Proposed Scheme 4 Experimental Results 5 Conclusions 2 Introduction Image data hiding employs original image to cover a secret message Secret message is imperceptibly inserted into the original image 3 Introduction (c.) Good data hiding technologies Imperceptibility High embedding capacity Trade-off between stego-image quality hiding capacity 4 Introduction (c.) Three categories of data hiding Spatial domain Frequency domain Quantization domain 5 Introduction (c.) 1 0 1 0 Spatial 103 103 Domain 104 105 106 108 109 0 1 0 1 200 201 202 203 204 205 206 207 Secret message is directly embedded into 1 1 0 0 inserted 185 spatial 187 188 188 189 191 192 192 domain 0 0 1 1 102 195 197 198 198 199 201 Least-significant-bits 194 194 51 56 61 66 71 76 81 86 90 95 100 105 110 115 120 161 163 164 168 171 173 179 181 183 185 186 188 Secret Message 103 102 103 104 104 105 108 109 135 201 201 202 202 204 204 207 207 174 176 185 187 188 188 189 191 192 192 190 192 194 194 195 197 198 198 199 201 51 56 61 66 71 76 81 86 90 95 100 105 110 115 120 135 161 163 164 168 171 173 174 176 179 181 183 185 186 188 190 192 Cover Image Stego-Image 6 Introduction (c.) 103 102 103 104 104 105 108 109 201 201 202 202 204 204 207 207 185 187 188 188 189 191 192 192 194 194 195 197 198 198 199 201 51 56 61 66 71 76 81 86 90 95 100 105 110 115 120 135 161 163 164 168 171 173 174 176 179 181 183 185 186 188 190 192 Stego-Image 1 0 1 0 0 1 0 1 1 1 0 0 0 0 1 1 Secret Message 7 Introduction (c.) -68 + 184i Domain -72 + 84i -80 + 36i -84 + 0i -80 - 36i -72 - 84i -68 - 184i Frequency 100 101 102 103 104 105 106 107 102 103 104 -33 - 81i -3 - 105 50i 106 18107 - 39i 32 - 27i 41 - 9i 52 + 13i 72 + 48i 200 is 201 204 206+ 14i 207 -34 Secret message into -1486+ 54i 27 + 30i 10 + 22i 1 directly + 202 25i 203 -10 +embedded 22i205 -23 + 2i -45 - 21i 200 201 202 203 204 205 206 207 -183 - 439i -14 - 15i -8 - 11i -7 - 13i 0 - 15i 12 - 16i 13 23 - 10i 39 + 11i 24 185 186 187 188 189 190 191 192 frequency domain 185 +186 187 188 189 -1328 0i -10 - 4i 0 - 8i190 191 6 -192 8i 8 + 0i 9 6 + 8i 0 + 8i 1 -10 + 4i 9772 + 0i 100- 763i 101 759 193 194 197 199 23 +198 10i 12200 +195 16i 196 1 0+ 15i 198 -8 -7 + 13i200 -8 + 11i 197 199 13 -34 - 2i -23 60 - 14i 65 -10 10 - 22i 50 55 -24 70- 22i75 180- 25i 85 11 70 75 80 85 52 - 13i 9i 105 32110 + 27i 115 18 90 95 41 +100 120+ 39i 135 -3 + 50i 110 115 120 135 Frequency Domain (Cover (Stego-Image) Image) 160 162 164 168 170 172 174 176 160 162 164 168 170 172 174 176 178 180 182 184 186 188 190 192 1 0 1 0 178 180 182 184 186 188 190 192 -183 39 - 11i 193 + 439i 194 195 196 -1486 -554i -45 + 21i 50 55 60 65 759 + 763i 72 - 48i 90 95 100 105 0 1 0 1 1 1 0 0 0 0 1 1 Cover Image Secret Message -14 + 15i 27 - 30i -33 + 81i Stego-Image 8 Introduction (c.) Quantization Domaint Uncompress Compress 1 1 Quantization-based images such as vector x 2 x 2 quantization (VQ) m x m x Codebook 9 Related Work Jo and Kim’s watermarking partitions the codebook into three sub-codebooks to hide watermark Chang and Wu’s scheme clusters codewords with difference size and performs cycle permutation Chiang and Tsai’s scheme divides the codebook into several sub-codebooks with codeword overlapping 10 Related Work (c.) Jo and Kim’s Watermarking Jo and Kim’s technique partitions the codebook into three sub-codebooks SC-1 , SC0 , SC1 SC codewords in which each Both and SC1of can be considered to represent 0 , SC10 consist codeword in one the bit - value of 0sub and-1codebook correspond s SC are not codeword suitable to in embed watermark to a-1similar the other sub - codebook 11 Related Work (c.) Embed 0 Cover Image SC-1 0 1 1 0 Watermark SC0 1 Embedded Image SC1 12 Related Work (c.) Chiang and Tsai´s Scheme 13 Related Work (c.) Sub-cluster Capacity(bit) Four-codeword 2 + 3 Three-codeword Three-codeword Two-codeword 1 One-codeword 0 14 Related Work (c.) Two codewords belongs to 3-member sub-cluster are considered together to embed three secret bits. Order Order Value in A in B in binary 0 0 000 (0) 0 1 001 (1) 0 2 010 (2) 1 0 011 (3) 1 1 100 (4) 1 2 101 (5) 2 0 110 (6) 2 1 111 (7) 2 2 Unuse 15 Proposed Scheme Color Image Quantization Palette Color Mapping Original Palette Index Table Quantized 16 Proposed Scheme (c.) Palette Partition Sub-palette Capacity(bit) Four-color 2 Three-color 1or 2 Two-color 1 One-color 0 17 Proposed Scheme (c.) Palette Partition with Overlapping Location Fourcolor Threecolor Twocolor 0 1 2 3 32 15 39 16 32 53 39 47 32 15 31 47 146 137 145 146 147 145 125 149 131 149 18 Proposed Scheme (c.) Lookup table for embed data Location 0 1 2 3 Fourcolor (00)2 (01)2 (10)2 (11)2 Threecolor (00)2 (1)2 (01)2 Two-color (0)2 (1)2 19 Proposed Scheme (c.) Location Four-color Threecolor Two-color 0 1 2 3 32 15 39 16 32 53 39 47 32 15 31 47 146 137 145 146 147 145 125 149 131 149 Location 0 1 2 3 Four-color (00)2 (01) 2 (10)2 (11)2 Threecolor (00)2 (1) 2 (01)2 NA Two-color (0)2 (1) 2 NA NA Quantized Color 146 67 39 149 Sub-palette Size 3 1 4 2 125(0) 67 32(00)2 53(01)2 15(01)2 39(10)2 47(11)2 16(11)2 Secret Message Case 1110…. Quantized Color = 146 Sub-palette Size = 3 147 replace 146 Secret Message “1” Embedded Embedded Color 147(1)2 137(1)2 146(00)2 145(01)2 2 131(0) 2 149(1) 2 20 Proposed Scheme (c.) Extraction Procedure Location Four-color Threecolor Two-color 0 1 2 3 32 15 39 16 32 53 39 47 32 15 31 47 146 137 145 146 147 145 125 149 131 149 Location 0 1 2 3 Four-color (00)2 (01) 2 (10)2 (11)2 Threecolor (00)2 (1) 2 (01)2 NA Two-color (0)2 (1) 2 NA NA 147 Index = 147 Secret Message = 1…. 21 Experimental Results RGB color images, “Airplane,” “Lena,” and “Pepper” of 512 × 512 pixels Airplane Images Lena Pepper Sub-Palette size Four-color Three-color Two-color Airplane 113(214) 3(9) 2(4) Lena 146(236) 2(4) 1(2) Peppers 71(141) 5(12) 22(42) 22 Experimental Results (c.) Performance of the proposed method Sub-palette Fourcolor Threecolor Twocolor Estimated Capacity Airplane 255,216 2,487 893 515,478 Lena 251,938 3,056 553 509,532 Peppers 197,045 14,947 26,457 445,508 Comparison: Ratio= Capacity/(CQ-PSNR) Method CQ Airplane Jo & Kim’s Chiang& Tsai’s Proposed PSNR Capacity Ratio PSNR Capacity Ratio PSNR Capacity Ratio 38.66 35.58 207,966 67,521 32.13 512,568 78,494 32.11 515,037 78,632 Lena 36.72 33.52 206,248 64,452 30.08 505,957 76,198 30.11 509,036 77,010 Pepper 33.07 30.67 150,756 62,815 27.28 428,020 73,924 27.31 442,989 76,908 Average 36.15 33.26 188,323 65,164 29.83 482,181 76,294 29.84 489,020 77,499 23 Conclusions An overlapping color palette partition based data hiding with improved data embedding procedure has been presented Proposed method provides a largest hiding capacity and supports better stego-image quality than Chiang & Tsai’s method 24 Proposed Scheme Palette Partition Algorithm Squared Euclidean Distance (SED) y Image quantization Euclidean Distance Index1 xi x1 , x2 ....., xk y j y1 , y2 ....., yk x k 2 d 2 ( x , y ) xd y d d 1 1/ 2 Index2 26 Related Work (c.) Chang & Wu’s Scheme Clusters codewords with difference size Performs cycle permutation Embeded size in a group I = log | G(I ) | 2 Index 32 15 39 16 53 Embeded data 00 01 10 11 00 47 01 27 Experimental Results (c.) Performance of the proposed method Sub-palette Fourcolor Threecolor Twocolor Estimated Capacity Airplane 255,216 2,487 893 515,478 Lena 251,938 3,056 553 509,532 Peppers 197,045 14,947 26,457 445,508 Comparison: Ratio=Capacity/(CQ-PSNR) Method CQ Airplane Jo & Kim’s Chang & Wu’s Chiang& Tsai’s Proposed PSNR Capacity PSNR Capacity PSNR Capacity PSNR Capacity 38.66 35.58 207,966 32.38 451,629 32.13 512,568 32.11 515,037 Lena 36.72 33.52 206,248 30.55 421,206 30.08 505,957 30.11 509,036 Peppers 33.07 30.67 150,756 27.11 410,582 27.28 428,020 27.31 442,989 Average 36.15 33.26 188,323 30.01 427,804 29.83 482,181 29.84 489,020 Ratio 65,164 696,745 76,294 77,499 28