| Summary: | 博士 === 國立東華大學 === 電機工程學系 === 98 === Following the widespread deployment of multimedia applications, the image compression techniques such as JPEG 2000 become an important factor in multimedia applications. The JPEG 2000 image compression standard is designed for a broad range of data compression applications. The two critical subsystems in JPEG 2000 are discrete wavelet transformation (DWT) and quantization. The DWT is central to the signal analysis and important in the JPEG 2000. However, DWT is quite susceptible to computer-induced errors. The errors can be spread to many output transform coefficients if the DWT is implemented by using lifting scheme. Additionally, in order to achieve the data compression, all the sub-bands of DWT are quantized by using quantization in JPEG 2000 encoder. However, the errors occur in hardware or software of quantization that the errors will contribute to additional distortion in the procedure of image encoding. On the other hand, as the advance in VLSI technology and feature size shrinks, the yield problem becomes an important design issue. However, the conventional yield improvement methodologies such as fault tolerance and defect tolerance may become inadequate to solve the yield problem. Hence, the error tolerance is introduced to improve the yield problem in 2003.
In this dissertation, two error tolerance designs are presented. An efficient error tolerance scheme (ETS) is firstly developed to detect the errors occurring in DWT for error tolerance evaluation in JPEG 2000 encoder and further produce the acceptable results. In the proposed ETS design, a pipeline-based DWT structure is developed to speed up the error detection process. Also, the proposed ETS design uses weighting sums of the DWT coefficients at the output compared with an equivalent check value derived from the input-data. With the proposed ETS design, the errors introduced at DWT can be effectively detected. For quantization, an error tolerance methodology (ETM) is continuously proposed to detect the error in quantization and further analyze the error effects in JPEG 2000 encoder. In ETM design, error tolerance weighting and brightness variation rate is developed to enhance the ability of error detection and to evaluate the capability of error tolerance. Additionally, the results of error detection can be further analyzed and evaluated to show the capability of error tolerance. Some standard images are used as test samples to verify the feasibility of the proposed ETS and ETM design. Finally, the experimental results and comparisons show that the proposed ETS and ETM have good performance in error detection and error tolerance capability for JPEG 2000 encoder applications.
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