2019 Volume 48 Issue 3 Pages 364-374
In subbnad image coding, we have obtained the optimum frequency band partition method which can determine both the optimum partition pattern in 2-dimensional frequency domain and the op-timum combination of quantizers for subbands based on the rate-distortion sense. This paper presents the optimum space-frequency partition method for subband image coding in order to improve the coding per-formance of our previous method. The proposed method optimizes the pruning of coefficient pixels in each subband from the rate-distortion sense to remove the redundancy in 2-dimensional spatial domain adding to the optimum partition pattern and the optimum combination of quantizers in our previous method. Also, the optimization algorithm for three parameters at the lower computational costs is developed using the tree structure between band blocks which is a small region of 2-dimensional frequency domain. Our experimental results show that the PSNR of the proposed method is about 2[dB] higher than our previous method at the same bit rate. Moreover, the coding performances of the proposed method are superior to those of the wavelet packet in spite of the computational costs of the proposed method is lower than the wavelet packet.
