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 d(CW 253, X)>THVQ Hide no secret code: ‘ 1 0000 11111101’ u 17

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 18

Extracting Secret in Residual Blocks ¡ Code 111001000000101100000011101… Hide using SMVQ Hide no secret Hide Secret: ‘ 1’ Hide using VQ Hide Secret: ‘ 0’ 19

Experiments Image size: 512 х512 20

Experiments u. State codebook size = 16 u. Codebook size= 256 21