| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 2004: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2003: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
A progressive to lossless embedded wavelet image coding (PLEWIC) has wide applicability, since lossy and lossless images can be reconstructed from a part and the whole of data encoded, respectively. Specifically, it does not cover only natural images, but also medical, satellite and art images. The PLEWIC can be realized by using a separable two-dimensional FLWT-ILWT system (SP-FLWT-ILWT), where FLWT and ILWT are forward and inverse lossless wavelet transforms, respectively. In lossy reconstruction, the reconstruction error of the FLWT-ILWT is much larger than that of FWT-IWT at high bit rates other than near lossless bit rates because of the rounding in lifting steps, where FWT and IWT are forward and inverse wavelet transforms, respectively. This results in low lossy compression performance of the PLEWIC.
In this report, we show that the reconstruction error of the non-separable FLWT-ILWT is smaller than that of the SP-FLWT-ILWT and propose a system which does not use an ILWT but an IWT. In this system, we must correct the mean value of each band. We also investigate a mixed type system which is obtained by applying repeatedly a 4-band non-separable FLWT for the lowest frequency band. The simulation shows that the PSNR of the reconstructed image of the non-separable FLWT followed by IWT is 2.7dB higher than that of the separable FLWT followed by ILWT at a bit rate and that a system using the mixed type system has good performance at all bit rates.
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