Image coding using optimized significance tree quantization

A number of recent embedded transform coders, including Shapiro's (1993) EZW scheme, Said and Pearlman's (see IEEE Trans. Circuits and Systems for Video Technology, vol.6, no.3, p.243-250, 1996) SPIHT scheme, and Xiong et al. (see IEEE Signal Processing Letters, no.11, 1996) EZDCT scheme employ a common algorithm called significance tree quantization (STQ). Each of these coders have been selected from a large family of significance tree quantizers based on empirical work and a priori knowledge of the transform coefficient behavior. We describe an algorithm for selecting a particular form of STQ that is optimized for a given class of images. We apply our optimization procedure to the task of quantizing 8/spl times/8 DCT blocks. Our algorithm yields a fully embedded, low-complexity coder with performance from 0.7 to 2.5 dB better than baseline JPEG for standard test images.