摘要
以小波轉換為基底的應用與架構設計已在許多的期刊與文獻中被大量的討論，並被提出作為下一代影像壓縮標準。利用小波轉換做影像處理的主要好處是在於在高壓縮率的條件下，依然能有不錯的影像品質。另外一個優點是高可伸縮性。根據這些特性，以離散小波轉換為基底的影像特別適合於網路的傳輸。但由於傳統的影像大都是以離散餘弦轉換為基底的影像。所以本論文提出一個能快速的將以離散餘弦轉換為基底的影像轉至以離散小波轉換為基底的影像的轉碼方法與轉碼器架構來轉碼已存在的傳統影像。

我們利用已知的轉換矩陣做矩陣運算，找到個新的轉換矩陣並且研究轉換流程。並根據新的轉換流程提出合適的轉碼器的架構。在做轉碼器架構設計時，我們將管線式(Pipeline)的概念加入，使得做整張影像的轉碼所需的時脈週期數約與單獨整張影像做離散小波轉換所需得時脈週期數一樣。我們的架構可支援兩種格式以支援新的影像壓縮標準，如JPEG2000與MPEG4。一種格式為以整張影像做離散小波轉換，另外一種是將影像分為若干個Tile，以Tile為單位做離散小波轉換。使用著可以自行選擇不同的格式並配合不同的編碼方式來完成整個轉碼系統。

根據TSMC 0.35um的Cell-library，我們所設計的轉碼器架構可達到50-MHz的工作頻率，所使用的閘數目(gate-count)為22305，所耗的功率為62mW。

Abstract
The wavelet-transform based applications and their architecture design have been widely discussed in literature, and already proposed for image compression standard of modern era. The main advantage of using DWT is to cope with high compression demand and still get good image quality. Another advantage is its high scalability. According to these features, DWT- based images are extremely suitable for transmission over the Internet. Nevertheless, most of the image data are DCT-based. For this reason, we propose a DCT-based to DWT-based image transcoder to convert the pre-existent image data.

We utilize the matrix operation of given transform matrices to get the new transform matrix and study the transcoding procedures. Accordingly, their architectures are proposed. We design the proposed transcoder based on the principle of pipelining. The proposed architecture can offer two formats of DWT to support the new image standards, such as JPEG2000 and MPEG4. One works on the whole image, and the other on a tile. It can be chosen by user to support different coding ways.

According to TSMC 0.35um Cell-library, our design of the mentioned transcoder can achieve 50-MHz working speed with 22305 gate-counts, consuming 62mW of power.

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