A Lifting-Based Wavelet Transform Supporting Non-Dyadic Spatial Scalability

In subband image and video compression, the issue of dyadic spatial scalability with a downsizing ratio of 2:1 has already been widely investigated. In some application scenarios, however, other downsizing ratios can be desirable. This paper proposes a wavelet coding scheme to support non-dyadic spatial scalability. By extending lifting-based transform structure, we show how wavelet transform can directly support non-dyadic spatial scalability. Specially, based on the extended lifting framework, a wavelet transform is designed to decompose an image with size 3W×3H to a low-pass subband with size 2W×2H and three high-pass subbands to support 3:2-ratio spatial scalability. The characteristic of proposed wavelet low-pass filter is investigated and experimental results show that the low resolution image produced by our scheme has good quality while the coding performance just has marginal loss compared to Daubechies 9/7 filter.