Abstract
In subband image coding, each subband signal is encoded by appropriate quantizer after an input image is divided into some subbands. According to the stochastic characteristics of input image, the optimum frequency band partition which can minimize the quantization noise power in the reconstructed image was proposed previously, in order to improve the coding performance for subband image coding. However, the partition pattern on the 2-D frequency domain of the previous method was invariable when the bit rate is changed. This paper presents new optimum frequency band partition which can determine both the optimum partition on the 2-D frequency domain and the optimum combination of quantizers with subband signals for a given bit rate. In the proposed method, the calculation algorithm with lower computational cost to obtain the optimum frequency band partition has been developed, in paying attention to the kurtosis of the quantized subband signals. It is seen in the experimental results that the improvement of the proposed method is about 0.5[dB] at the lower bit rate compared with the previous method.
