Advanced Compression Techniques for Simple Images and Intrinsic Mode Functions
Date Issued
2014
Date
2014
Author(s)
Chen, Ying-Jou
Abstract
In this thesis, two compression techniques are proposed. First, we design an image coding scheme for simple images in order to enhance the compression efficiency of the state-of-the-art compression standards, namely Joint Photographic Expert Group (JPEG) and JPEG2000. Second, we study the compression method for the Intrinsic Mode Functions (IMF) and propose an effective coding approach for IMFs.
For simple image compression, a segmentation-based approach is developed. In this approach, the descriptors of the simple image are divided into two parts: the contour-related information and the content-related information. First, the simple image is partitioned into several parts where the pixel values are highly concentrated. A novel boundary description technique based on 2nd order polynomial approximation is adopted and the descriptions are stored as the contour-related information. Second, the content within each partition is classified by the proposed criterion following with a mechanism named majority voting to generate the approximated image. Then, the residual image could be derived by the original simple image and the approximated image. To encode the residue, we propose a context-based arithmetic coder based on the neighborhood information and the classification derived in the second step to improve the compression efficiency. The content-related information includes the classification for each partition, the approximated image, and the residue. Simulations show that the proposed compression technique outperforms JPEG, JPEG2000, and other existing methods for simple image compression.
For the compression of the IMF, we investigate the characteristics of the IMFs with different rankings and design an adaptive scheme that using different coding methods for the IMF with different rankings. If the total number of the IMFs is N, while dealing with the IMF with ranking number less or equal to N/2, the transform coding would be applied for compression. Otherwise, the newly devised approach named enhanced extreme coding would be used to record the IMF. In the enhanced extreme coding approach, the point selection is performed firstly following by the point encoding process. The point selection procedure is to find the significant points of the IMF while the point encoding process uses the concept of predictive coding to eliminate the correlations among the selected points. The proposed mode switching compression technique achieves better compression performance than the single mode compression scheme.
Subjects
影像編碼
影像壓縮
邊緣近似
JPEG
JPEG2000
預測編碼
轉換編碼
本質模態函數
經驗模態分解
Type
thesis
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