A method for estimating coding gain of an orthogonal wavelet transform considering higher-order statistics

In applications such as subband coding, the coding gain is a useful evaluation measure for representing the bit-rate reduction performance of the subband filter for the object of coding. It is widely used in the estimation of coding performance and the design of subband filters. To estimate the coding gain requires knowledge of the probability density distribution of the object of coding and the decomposed subband series. Identification of the probability density function, however, is in general difficult. Consequently an approximation is often used in the estimation of the coding gain, where it is assumed that the probability density distributions of the object of coding and all subband series are the same. Thus, estimation of the coding gain contains an error for data, such as images, where this assumption is not satisfied. This paper notes that the probability density distribution of the subband decomposed image can be well approximated by a generalized Gaussian distribution and proposes a method for a more accurate estimation of the coding gain in the orthogonal wavelet transform attained by a variety of subband filter, using the higher-order statistics of the object of coding. The coding gain is estimated for several objects of coding. Comparing the result to the actually measured value, it is shown that the accuracy of estimation is greatly improved in the proposed method, compared to the method based on an approximation. (C) 1998 Scripta Technica.