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Wavelet Transform and SPIHT Coding. Outline Wavelet Transform SPIHT Coding Multiple Description Coding.

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Presentation on theme: "Wavelet Transform and SPIHT Coding. Outline Wavelet Transform SPIHT Coding Multiple Description Coding."— Presentation transcript:

1 Wavelet Transform and SPIHT Coding

2 Outline Wavelet Transform SPIHT Coding Multiple Description Coding

3 Wavelet Transform WHY Transform ? (1)energy compaction 能量集中在較少的區塊中 (2)decorrelation 去除相鄰點之間的相關性

4 Wavelet Transform

5 Discrete Wavelet Transformation LH LL LH HL HH

6 Discrete Wavelet Transformation LL1HL1 LH1HH1 LL2HL2 HL1 LH2 HH2 LH1HH1 HL2 HL1 LH2HH2 LH1HH1 LL3HL3 LH3HH3 第一階第二階 第三階

7 5/3 Lena 2-level 96.64%0.41%0.92% 0.35%0.94% 0.27%0.43%

8 使用 LL2 回復 PSNR= dB

9 Data Extension

10 Period or Symmetric Extension bpp9/710/185/39/7M5/11A5/11C13/7C13/7T / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / /39.74 Lena

11 SPIHT Coding DWT SPIHTIWT

12 SPIHT Coding Proposed by Said and Pearlman in 1996 Regard tree as the unit Idea of zerotree A. Said and W. A. Pearlman, “A new, fast, and efficient image codec based on set partitioning in hierarchical trees, ” IEEE Trans. Circuits Syst. Video Technol., vol. 6, no. 3, pp , June 1996.

13 SPIHT Coding

14 Two Type Zerotree TYPE A TYPE B

15 SPIHT Coding Initial threshold = T T=T/2 LIP: List of Insignificant Pixel LIS: List of Insignificant Set LSP: List of Significant Pixel

16 Compression Performance with Various Filters bppD2D4D6D89-tap9/710/185/39/7M5/11A5/11C13/7C13/7T Lena

17 SPIHT 的錯誤回復 因封包遺失所造成的圖形品質降低 使用一些方法將遺失的部份回復

18 Multiple Description Coding 利用額外的資訊去達到錯誤保護的效果 先附加較重要的資料

19 Multiple Description Coding

20

21 Lena 0.125bpp 10% packet lost Unprotect PSNR=14.29dBMDC PSNR=27.95dB


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