分类： 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间： 2023-09-19
摘要： To accelerate the fractal decoding process, a minimum iterated function system based fast fractal decoding method was proposed in this study. In fractal encoding process, we found that there exists a minimum domain block set (MDBS) which can provide the best-matched domain blocks for all range blocks, and then the domain blocks of MDBS, the range blocks within MDBS, and the associated mapping operations between them constitute the minimum iteration function system (MIFS). In decoding process, MIFS was first recovered in the first iteration. Then, in each of the second to penultimate iterations, only the range blocks within MDBS are reconstructed, and the computations of reconstructing the remaining range blocks can be saved. Finally, all range blocks are reconstructed to obtain the decoded image in the last iteration. Four fractal encoding methods were adopted to assess the performance of the proposed method. Experimental results show that the proposed method can complete the decoding process with fewer computations.
分类： 计算机科学 >> 计算机应用技术 提交时间： 2023-09-06
摘要： In this study, an adaptively hybrid method was proposed to improve the performance of fractal coding methods. First, we found that the range blocks with large variances (RBLVs) play a crucial role in degrading decoded images, and the effect of the remaining range blocks with small variances (RBSVs) can be ignored. Second, RBLVs were designed to be encoded in an extended domain block pool (EDBP), and the remaining RBSVs were encoded with the no-search fractal encoding method. Moreover, an effective method to adaptively divide the range blocks into the above two categories was proposed. Finally, four fractal coding methods were adopted to assess the performance of the proposed method. Experimental results show that, compared with the previous methods, the proposed method can achieve better-decoded image quality with fewer bits per pixel and fewer computations.
分类： 计算机科学 >> 计算机应用技术 提交时间： 2023-08-25
摘要： To predict fractal decoded image quality more efficiently, an effective decoded image quality prediction method was proposed in this study. In fractal encoding process, the dynamic range of the linear correlation coefficients (LCCs) between range blocks and their best-matched domain blocks was greatly extended by several outliers which increased uncertainty and resulted in reduced prediction accuracy. To remove the interference of outliers, we introduced the effective minimum and maximum of LCCs, which provided the effective bottom and top limits of the actual percentage of accumulated collage error (EBL-APACE and ETL-APACE), respectively. Further, when EBL-APACE reached a large percentage, the average collage error (ACER) can be estimated, and the decoded image quality can be predicted directly.Experimental results show that compared with the previous method, the proposed method can provide higher prediction accuracy with fewer computations.
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