CCC 2 Vector Quantization VQ Concept Encoding and

CCC 2

Vector Quantization (VQ) Concept Encoding and Decoding 3

Vector Quantization (VQ) Image compression technique h w Image Index table Vector Quantization Encoder 4

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機密影像 (64*64 pixels) Original image (512*512 pixels) 7

Side Match Vector Quantization (SMVQ) Concept Encoding and Decoding 8

Side Match Vector Quantization (SMVQ) Image compression technique h w 131 137 132 131 129 130 137 132 131 131 134 140 Image Seed Blocks (VQ) Residual Blocks (SMVQ) Side Match Vector Quantization Encoder 9

Side Match Vector Quantization Encoder (130, 137, 132, 131, ? , ? , 134, ? , ? , 140, ? , ? ) from Codebook Residual Block (forecasted pixels) Index value 12 to encode block X 10

Side Match Vector Quantization Decoder Using VQ Decoder Using SMVQ Decoder Index Table Decoded Block Residual Block (forecasted pixels) 11

A Steganographic Method for Hiding Secret Data Using SMVQ 12

Hiding Secret data u Seed Blocks (VQ) u Residual Blocks (SMVQ) Original image (512*512 pixels) 13

SMVQ Residual Block (forecasted pixels) d(CW 12, X)<THSMVQ code: ‘ 1 1100’ u d(CW 12, X)>THSMVQ VQ encoder code: ‘ 0 10110010’ u 14

Hiding Secret in Residual Blocks (SMVQ) ¡ Secret message 1 0 1 1… Residual Block (forecasted pixels) u d(CW 12, X)<THSMV Q code: ‘ 1 1100’ u d(CW 12, X)>THSMV Q VQ encoder code: ‘ 0 10110010’ 15

Hiding Secret in Residual Blocks (SMVQ) ¡ Secret message 1 0 1 1… d(CW 1, X)<THSMVQ code: ‘ 1 0001’ u Residual Block (forecasted pixels) d(CW 1, X)>THSMVQ VQ encoder code: ‘ 0 10110010’ u 16

Hiding Secret in Residual Blocks (VQ) ¡ Secret message 1 0 1 1… Residual Block (original pixels) d(CW 253, X)<THVQ code: ‘ 0 11111101’ u 17

Hiding Secret in Residual Blocks (VQ) ¡ Secret message 0 1 1 0… Residual Block (original pixels) d(CW 2, X)>THVQ Hide no secret code: ‘ 1 0000 11111101’ u 18

Image Seed Blocks Using VQ: hide no secret (“ 0” + 8 -bits) 重點: 全部沒有藏 Residual Blocks Using SMVQ: hide secret (“ 1” + 4 -bits) Using VQ 1. hide secret (“ 0” + 8 -bits) 2. hide no secret (“ 1” + “ 0000” + 8 -bits) 重點: 1. 使用SMVQ的Block一定有藏 2. 使用VQ的Block有的有藏， 有的沒藏 19

Extracting Secret in Residual Blocks ¡ Code 111001000000101100000011101… Hide using SMVQ Hide no secret Hide Secret: ‘ 1’ Hide using VQ Hide Secret: ‘ 0’ 20

Experiments Image size: 512 × 512 21

Experiments State codebook size = 16 Codebook size Encoding distribution in residual blocks (the number of blocks) Hidden data PSNR Bit rate Time (bits) (d. B) (bpp) (sec. ) SMVQ VQ VQ without secrets 128 6943 7629 1557 14572 27. 96 0. 44 6. 7 256 9253 6473 403 15726 29. 37 0. 42 12. 0 512 9357 6281 491 15638 30. 19 0. 45 26. 6 1024 9475 6497 15972 30. 74 0. 47 66. 1 22

Experiments Codebook size = 256 State codebook size Encoding distribution in residual blocks (the number of blocks) Hidden data PSNR Bit rate Time (bits) (d. B) (bpp) (sec. ) SMVQ VQ VQ without secrets 16 9253 6473 403 15726 29. 37 0. 42 12. 0 32 10404 5323 402 15727 29. 50 0. 45 11. 7 64 11084 4627 418 15711 29. 61 0. 48 12. 9 128 11672 4017 440 15689 29. 45 0. 52 17. 1 256 11170 4539 420 15709 29. 71 0. 57 31. 4 23