1998 Fiscal Year Final Research Report Summary
Research on Region Adaptive Image Compression Algorithms and Integrated Schemes
| Project/Area Number |
09450152
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
情報通信工学
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| Research Institution | NAGOYA UNIVERSITY |
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Principal Investigator |
TANIMOTO Masayuki Nagoya University, Graduate School of Engineering, Professor, 工学研究科, 教授 (30109293)
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| Project Period (FY) |
1997 – 1998
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| Keywords | image compression / fractal image coding / region adaptive image coding / range block / block matching / fast algorithm / merge criterion / error propagation |
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| Research Abstract |
Main results obtained in the research are listed below.
(a) We studied new region adaptive fractal image coding in which primitive blocks are merged into a variable size range block. We have obtained following results.
i. In the merging process of primitive blocks, the use of increase of overall error caused by block merging results in the improvement of SN ratio by 1dB.
ii. It is effective to the scheme of (i) that the threshold of increase is not constant but firstly small values and increased gradually.
iii. The scheme where a range block is re-merged with surrounding blocks in reverse order when a range block merged in an order is obtained reduces influence of merging order.
iv. The above schemes of (i) - (iii) achieve the improvement of compression performance by 2dB.
v. A new fractal image encoding scheme which can select decoding iteration times shows decoding are finished within a constant time.
(b) We studied block matching which is the core of the new region adaptive image compression and obtain following results.
i. A mathematical algorithm that reduces calculation times of MSE between two blocks is proposed. It calculates about 3 times faster than the conventional scheme.
ii. Moreover, modification of searching order and restriction of searching range result in the half of processing time.
(c) In image compression schemes which depend on the region already encoded, a new method is proposed that the data is completely decoded and that the inner buffer is modified until decoding process of the next region starts if decoding process is not completed because of a delay of encoded data or a break of iteration. This method greatly reduces error propagation.
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