| Summary: | 博士 === 國立交通大學 === 電機與控制工程系所 === 96 === After the discrete cosine transform (DCT) was widely used in image compression, discrete wavelet transform (DWT) was the new dominated transform for research and industrial applications, and it has been adopted in the new still-image compression standards (e.g. JPEG2000) and video compression standards (e.g. MPEG-4 and H.264/AVC). In literature, the realization of DWT was convolution-based in early days, and for better computation efficiency, saving memory space, integer-to-integer transform, parallel processing, and boundary extension problem the lifting-based DWT was proposed later. Lifting-based DWT is still an important research topic, since it is more flexible than the convolution-based DWT to adopt new functionalities.
In this dissertation, the lifting-based DWT was studied, and a lifting-based direction-adaptive DWT was discussed. Then, the lifting-based shape-adaptive DWT (LSA-DWT) and the lifting-based shape-direction-adaptive DWT, which was adaptive in shape and direction, were proposed. Because SDA-DWT has the adaptabilities of shape and direction, by paying affordable cost, we can achieve superior improvement in image compression. Beside lifting-based SA-DWT and SDA-DWT, the combination of lifting-based DWT and vector quantization (VQ) was discussed in the dissertation.
|
|---|
