採用小波與壓縮感知處理的分散式影像編碼方法

A Wavelet-based Distributed Video Coding Method with Compressive Sensing

林聖艦(Sheng-Chien Lin)

指導教授 ： 王家祥

國立清華大學/電機資訊學院/資訊工程學系/碩士(2010年)

https://doi.org/10.6843/NTHU.2010.00442

摘要

在現代的影像壓縮技術中，為了實現高壓縮率，編碼器利用了幀(frame)內部空間上的相關性(intra frame coding)和幀與幀在時間上的相關性(inter frame coding)，而在解碼端，解回一幀所需的複雜度遠小於編碼端。然而，在某些應用上，我們會使用一些缺乏記憶體與計算能力的裝置。分散式影像編碼(distributed video coding)在此情境下有很大的幫助，根據分散式來源編碼(distributed source coding)的概念，分散式影像編碼強調在一個低複雜度的編碼器，與一個計算能力較高的解碼器，這種概念類似壓縮感知(compressive sensing)。因此，在本篇論文中，我們討論如何將壓縮感知應用在分散式影像編碼上。我們提出一個採用小波(wavelet)與壓縮感知處理的分散式影像編碼方法， 利用再小波頻域上的差值找出影像的稀疏(sparse)表示，我們同時利用skip block、量化(Quantization)及熵編碼(Entropy coding)降低bit-rate，在解碼端利用簡單的side information幫助解碼。我們主要的貢獻在進一步地降低編碼器的編碼時間，和其他分散式影像編碼演算法相比，實驗結果展示我們所提出編碼器能更省能量，這讓我們提出的編碼器有能力應用在一些電力與計算能力有限的裝置上。

關鍵字

分散式影像編碼 ； 壓縮感知 ； 小波

並列摘要

In the modern video compression techniques, for achieving high compressive rate, the encoder would exploit all spatial (intra coding) and temporal (inter coding) correlation on every frame. The complexity to decode a frame is much less than to encode one. However, in some applications we would adopt some devices which lack memory and computing ability. Distributed Video Coding (DVC) is helpful in this situation. Based on the theoretic results of Distributed Source Coding (DSC), DVC focuses on a lower complexity encoder and a powerful decoder. This feature is very similar to the concept of Compressive Sensing (CS). Therefore, in this thesis, we discuss how to employ CS into DVC. We proposed a wavelet-based distributed video coding method with compressive sensing. To find a sparse representation for video frames, we use the difference on the wavelet domain. We also adopt skip block, quantization, and entropy coding to reduce the bit-rate. We use simple side information for helping decoder. The main contributions of our works are further reduction of complexity and coding time of the encoder. Compared with other DVC algorithms, the experimental results shows proposed encoder can save more energy. This makes the proposed encoder is able to be implemented in the devices with limited power or computational ability.

並列關鍵字

distributed video coding ； compressive sensing ； wavelet

參考文獻

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