由於多媒體技術的迅速發展，使用者對資訊的需求量大增，其
中又以影像傳輸所需的資料量最大，故在有限的記憶體儲存容量
中，有效的壓縮及傳輸方法是迫切需要的。其中離散小波轉換技術
之特點非常適合使用於影像壓縮，而基於離散小波轉換技術下所發
展的SPIHT 壓縮方法亦有許多優點，不僅能在無雜訊干擾的情況
下壓縮出高品質的影像，且編解碼效率高，亦能提供漸進式傳輸。
不過SPIHT 壓縮在影像傳輸上卻有一致命缺點，即是其編碼後的
位元序列對雜訊極為敏感，即使只是一個位元的錯誤也有可能造成
不可補救的錯誤。
在本論文中，我們研究了SPIHT 編碼的位元序列特性，並依其
特性將此缺點進一步改善，使其在通道中能有效對抗雜訊且順利被
傳送至接收端。我們假設通訊場景為無回傳機制，因此在錯誤保護
機制中我們亦同時使用了前向錯誤更正。在所提出的傳輸機制中，
我們將經由SPIHT 編碼後的位元序列打包成數個固定長度的封包，
並藉由我們所提出的訊雜比最佳化演算法分別配予不同等級的分集
階數，達到不等錯誤保護，並加強保護重要位元或捨棄次要位元，
使能保證接收端收到最佳品質的影像。我們以模擬來驗證此系統的
效能，並與其他兩種機制作為比較，其中一種亦為不等錯誤保護，
而另一種則為同等錯誤保護。實驗結果階能證實我們所提出的機制
不僅優於同等錯誤保護機制，亦勝於現有的不等錯誤保護機制。

Due to the rapid development of multimedia technologies, the effective compression and transmission methods against the limited storage space is needed. The characteristics of wavelet transform make it suitable for image compression. Coupled with the discrete wavelet transform, set partitioning in hierarchical trees (SPIHT) is a highly efficient image compression technique that allows for progressive transmission. One issue, however, is that its decoding can be extremely sensitive to errors in the embedded bit stream generated by the SPIHT encoder. The transmission of images over noisy channels is still a challenging problem.
In this thesis, we address the issue of transmitting SPIHT-encoded images via
noisy channels, wherein errors are inevitably encountered. The communication scenario assumed in this thesis is that no acknowledge path is available from the receiver to the transmitter, and thus error protection has to be done by forward error correction.
In our scheme, the original SPIHT code sequence is packetized. The resulted packets are then allocated with different diversity orders for unequal error protection (UEP) so that the decoded image quality is optimal (in the sense of the expected SNR) at the receiver. Experimental results show that the proposed scheme significantly improves the quality of the decoded images as compared to the case of no diversity allocation. Moreover, comparisons with existing UEP techniques for transmitting SPIHT-encoded images are made. The results show that our method outperforms those existing UEP techniques.

[1] J. Shapiro, "Embedded image coding using zerotrees of wavelet coefficients,''
IEEE Trans. on Signal Processing, vol. 41, no. 12, pp. 3445-3462, Dec. 1993.
[2] A. Said and W. A. Pearlman, ''A new, fast and efficient image codec based on
set partitioning in hierarchical trees,'' IEEE Trans. on Circuits and Systems for
Video Technology, vol. 6, pp. 243-250, June 1996.
[3] L. C. Ramac and P. K. Varshney, ''A wavelet domain diversity method for transmission
of images over wireless channels,'' IEEE Journal on Slected Areas In
Communication, vol. 18, no. 6, pp. 891-898, June 2000.
[4] Y. Sriraja and T. Karp, ''Error Protection of Packetized SPIHT Bit Streams for
Image Transmission Over Noisy Channels,'' Signals, Systems and Computers,
2005. Conference Record of the Thirty-Ninth Asilomar, pp. 864-868, 2005.
[5] M. A. Khan and E. Khan, ''Error resilient technique for SPIHT coded color images,''
Multimedia, Signal Processing and Communication Technologies, IMPACT
'09. International, pp. 237-240, 2009.
[6] J. Kim, R. M. Mersereau, and Y. Altunbasak, ''Error-resilient image and video
transmission over the Internet using unequal error protection,'' IEEE Trans. on
Image Processing, vol. 12, no. 2, pp. 121-131, Feb. 2003.
[7] A. A. Alatan, M. Zhao, and A. N. Akansu, ''Unequal error protection of SPIHT
encoded image bit streams,'' IEEE Journal on Slected Areas In Communication,
vol. 18, no. 6, pp. 814-818, June 2003.
[8] A. Bouridane, F. Khelifi, A. Amira, F. Kurugollu and S. Boussakta, ''A Vary Low
Bit-Rate Embedded Color Image Coding with SPIHT,'' in Proc. IEEE Int. Conf.
Acoustic, Speech and Signal Processing, vol. 4, pp. 689–692, Apr. 2004.
[9] N. Thomos, N. V. Boulgouris, and M. G. Strintzis, ''Wireless image transmission
using turbo codes and optimal unequal error protection,'' IEEE Trans. on Image
Processing, vol. 14, no. 11, pp. 1890-1901, Nov. 2005.
[10] R. C. Gonzolez, R. E. Woods, Digital Image Processing second edition, Prentice
Hall, 2002.
[11] M. Antonini, M. Barlaud, P. Mathieu, and I. Daubechies, ''Image coding using
wavelet transform,'' IEEE Trans. on Image Processing, vol. 1, no. 2, pp. 205-220,
April 1992.
[12] I. Daubechies, ''Orthonormal bases of compactly supported wavelets,'' Communications
on Pure and Applied Mathematics, vol. 41, pp. 909-996,1988.
[13] R. M. Rao, A. S. Bopardikar, Wavelet Transforms, Massachusetts: Addison Wesley
Longman, 1998.
[14] H. Man, F. Kossentini and M. J. T. Smith,''A family of efficient and channel
error resilient wavelet/ subband image coder,'' IEEE Trans. Circuit & Systems
for Video Technology, vol. 9, pp. 95-108, Feb.1999.
[15] L. Yao, L. S. Cao, ''Turbo Codes based Image Transmission for Channels with
both Random Errors and Packet Loss,'' IEEE International Conference on Commun.
, pp.1784-1789, 24-28 June 2007.
[16] Q. Li, X. Zhang, ''Robust SPIHT-Coded Image Transmission over Wireless
Channels Using Packetization,'' IEEE Image and Signal Processing, International
Congress , pp.1-4, 17-19 Oct. 2009.
[17] C. L. Tung, T. S. Chen, W. -H. Wang, S. T. Yeh, ''A New Improvement of SPIHT
Progressive Image Transmission,'' IEEE Fifth International Symposium on Multimedia
Software Engineering, pp. 180- 187, 10-12 Dec. 2003.
[18] A. Nosratinia, J. Lu,B. Aazhang, ''Source-Channel Rate Allocation for Progressive
Transmission of Images,'' IEEE Trans. Commun., vol. 51, no. 2, pp. 186-
196, 1996.
[19] A. Mohr, E. Riskin, and R. Ladner, ''Unequal loss protection: Graceful degradation
of image quality over packet erasure channels through forward error correction,''
IEEE Journal on Selected Areas of Communications, vol. 18, 2000.
[20] V. Chande and N. Farvardin, ''Progressive transmission of images over memoryless
noisy channels,'' IEEE Journal on Slected Areas In Communication, vol. 18,
no. 6, pp. 850-860, 2000.