1997 Fiscal Year Final Research Report Summary
Multispectral Image Compression Using Wavelet Transform
| Project/Area Number |
08650446
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | KANAZAWA INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
TAKEBE Tsuyoshi Kanazawa Institute of Technology, Faculty of Technology, Professor, 工学部, 教授 (20019699)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUMURA Shuitsu Kanazawa Technical College, Professor, 電気工学科, 教授 (50064457)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Multispectral Image / Wavelet Transform / DCT / Vector Quantization / Lossy Image Compression / Filter Bank |
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| Research Abstract |
High efficiency lossy image comression is investigated for seven band Landsat Thematic Mapper imagery. The image of north part of Kanazawa city including Kahoku lake is used for testing.
1.3-D DCT and scalar/vector quantization
Removing Band 6 image, inter-and inter-band correlation between pixels in other 6 band images is removed by 3-D DCT.Band 6 image is solely compressed, because it differs greatly from other band images in spatial resolution. DCT coefficients are denoted F (i, j, k) where i : horizontal 8th order, j : vertical 8th order and k : band directional 6th order variables. As the coefficients with the same i, j and k has relatively small variance, they are united to form a block.
In the DC block, the coefficients are DPCM-entropy coded. The other blocks are classified into 5 groups (G) according to the value of i+j+k. G1-G3 are scalar quantized and entropy coded, G4 is vector quantized with size of 1*4 and G5 is discarded.
Bit-rate is abjusted by the ratio of the number of discarded small power vectors to the total number of vectors. In bit-rate greater than 1.2 bpp, PSNR greater than 32 dB is obtained.
2.Wavelet transform and interband differential coding
The image of band 2 is two stage wavelet transformed and directionally vector quantized. Then differential pictures between the other band image and the reconstructed band 2 image are 3-D DPCM-scalar and vector quantized in the similar way to section l. As a result, 0.3 dB higher PSNR is obtained in the bit-rate of 1.2-1.6 bpp compared with those of 3-D DCT.
3.2-CH perfect reconstruction IIR filter bank
A filter bank system is developed such that all the analysis and Synthesis filters have linear phase and satisfy the power complementary condition approximately.
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