An Adaptive Quantization Scheme for 2-D DWT Coefficients

Two-dimensional Discrete Wavelet Transform (2-D DWT) is an effective tool for image compression and hence attracts much attention in recent years. In this paper, we propose an adaptive quantization approach which quantizes the DWT coefficients according to their characteristics. Unlike the uniform quantization which uses a fixed quantization interval, the proposed scheme applies two asymmetric interval widths to one single sub-band. According to the experiment results, it leads to a superior image quality while maintaining the same compression ratio.