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Please use this identifier to cite or link to this item: http://hdl.handle.net/2031/4487

Title: Data compression for image-based relighting using radial basis functions
Other Titles: Li yong ban jing ji di han shu ya suo guang zhao tu xiang shu ju
利用半徑基底函數壓縮光照圖像數據
Authors: Choy, Kwok Hung (蔡國雄)
Department: Dept. of Electronic Engineering
Degree: Master of Philosophy
Issue Date: 2004
Publisher: City University of Hong Kong
Subjects: Image compression
Image processing -- Digital techniques
Notes: CityU Call Number: TA1632.C56 2004
Includes bibliographical references (leaves 69-78)
Thesis (M.Phil.)--City University of Hong Kong, 2004
viii, 78 leaves : ill. ; 30 cm.
Type: Thesis
Abstract: In image based rendering with changing illumination, there is a set of precaptured images under fixed viewpoint but various sampling light directions. The pre-captured images are called reference images. Each reference image describes the appearance of an object under various light directions. Given a novel illumination condition, a novel image can be synthesized from reference images. The quality of the synthesized image depends on the number of reference images used. Therefore, an efficient compression algorithm for reference images is a must. This thesis proposes a compression scheme based on spherical radial basis function (SRBF) networks. The compression algorithm is divided into two levels. In the first level, we use one SRBF network to approximate the plenoptic property of each pixel. That means, the plenoptic property of every pixel is represented by a number of SRBF weights. Although a simple least square method can be used for extracting SRBF weights, the rendering image is very sensitive to the quantization noise introduced by the second level compression. So a constrained least square algorithm is proposed. Since the same SRBF weights from different pixels can be organized as a SRBF relighting map whose property is similar to an image, we then apply a wavelet-based compression technique to compress the SRBF relighting maps. Simulation results show that our proposed approach is superior to compressing the reference images with JPEG, JPEG2000 and MPEG in terms of compression ratio and reconstruction error. Compared with the spherical harmonic (SH) approach, the complexity of using the SRBF approach to render a novel image is much lower while the image quality is comparable. The way to allow users to interactively and real-time control the illumination of a scene is also discussed.
Online Catalog Link: http://lib.cityu.edu.hk/record=b1929006
Appears in Collections:EE - Master of Philosophy

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