画像の予測符号化方式には，先に走査した画素の値だけrnを用いて予測を行う外挿予測と後に走査される画素の値もrn用いて予測を行う内挿予測の二つの方式がある．内挿予測rnは，外挿予測に比べて予測性能が高く，予測誤差電力をよrnり低減できるが，復号時に符号化誤差電力を増大させてしrnまう問題がある．%An optima] quantization ordering in the feedback quantization scheme for interpolative prediction coding designed to reduce the coding error power is proposed. This method adaptively selects the optimal quantization order to minimize the coding error power from candidate orders for each one dimensional block of 9x1 pixels. These candidate orders can be determined through a numerical analysis of the coding error with respect to all the quantization orders. Simulation results show that the proposed method can effectively reduce the error power and that selecting the optimal order from only four candidate orders can improve the PSNR by about 2 dB, which is just 0.36 dB below the heighest quality image decoded using all 5040 candidate orders. In the case of two-dimensional blocks, although the numerical analysis shows that the coding error power is almost identical among all the possible orders, simulation results demonstrate that selecting the optimal order from four orders in horizontal and vertical directions improves the PSNR by 2.6dB in the case of an 8x8 block.
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