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視訊通訊 homework#2

視訊通訊 homework#2. 2013.11.27 曾民佑. Outline. Program Flow Chart Error correction (12,8) Hamming Code (7,4) Hamming Code Design LSB by myself Photo retouching Result LSB is zero LSB is random Design LSB by myself Conclusion. Program Flow Chart. (12,8) Hamming Code.

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視訊通訊 homework#2

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  1. 視訊通訊homework#2 2013.11.27 曾民佑

  2. Outline • Program Flow Chart • Error correction • (12,8) Hamming Code • (7,4) Hamming Code • Design LSB by myself • Photo retouching • Result • LSB is zero • LSB is random • Design LSB by myself • Conclusion

  3. Program Flow Chart

  4. (12,8) Hamming Code [ m3 , m4 , m5 , m6 ] IGS code of pixel[ i ] [ m9 , m10 , m11 , m12 ] IGS code of pixel[ i+1 ] [ p1 , p2 , p4 , p8 ] Parity bits p1 = xor ( m3 , m5 , m7 , m8 , m11 ) p2 = xor( m3 , m6 , m7 , m10 , m11 ) p3 = xor( m5 , m6 , m7 , m12) p4 = xor( m9 , m10 , m11 , m12)

  5. (12,8) Hamming Code Check： c1 = xor ( r1 , r3 , r5 , r7 , r9, r11 ) c2 = xor ( r2 , r3 , r6 , r7 , r10, r11 ) c3 = xor ( r4 , r5 , r6 , r7 , r12 ) c4 = xor ( r8 , r9 , r10 , r11 , r12 )

  6. (7,4) Hamming Code parity bits message bits m = [ m0 , m1 , m2 , m3 ] IGS code of pixel[ i ] p = [ p0 , p1 , p2 ] Parity bits

  7. (7,4) Hamming Code

  8. (7,4) Hamming Code Syndrome：

  9. Design LSB by myself If ( Ii – Ii+1 == 16 & Ii – Ii-1 == 16 ) Ii = Ii – 9 else Ii = Ii+ rand( +2 , +1 , 0 , -1 , -2 )

  10. Design LSB by myself IGS source design by myself

  11. Photo retouching average = sum( I1 , I2 , I3 , I4 , I6 , I7 , I8 , I9 ) / 8 threshold = 64 If ( | I5 – average| >= threshold ) I5 = average

  12. Result (LSB is zero) Error rate：1% IGS code with (12,8) Hamming code IGS code without error correction

  13. Result (LSB is zero) Error rate：1% IGS code with (7,4) Hamming code IGS code without error correction

  14. Probability .

  15. Result (LSB is zero) Error rate：1% IGS code with (12,8) Hamming code& photo retouching IGS code without error correction

  16. Result (LSB is zero) Error rate：1% IGS code with (7,4) Hamming code& photo retouching IGS code without error correction

  17. Result (LSB is zero) Error rate：15% IGS code with (12,8) Hamming code IGS code without error correction

  18. Result (LSB is zero) Error rate：15% IGS code with (7,4) Hamming code IGS code without error correction

  19. Result (LSB is zero)

  20. Result (LSB is random) Error rate：0% IGS code (LSB is random) IGS code (LSB is zero)

  21. Result (LSB is random)

  22. Result (design LSB by myself) Error rate：0%

  23. Result (design LSB by myself)

  24. Compression Ratio

  25. Conclusion • Performance • (7,4) Hamming Code > (7,4) Hamming Code > No error correction • In low error rate , LSB is design by myself > LSB is zero > LSB is random , but equally matched in high error rate. • Photo retouching has higher performance in high error rate than without photo retouching.

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