Hierarchical Context-based Pixel Ordering

We present a context-based scanning algorithm which reorders the input image using a hierarchical representation of the image. Our algorithm optimally orders (permutes) the leaves corresponding to the pixels, by minimizing the sum of distances between neighboring pixels. The reordering results in an improved autocorrelation between nearby pixels which leads to a smoother image. This allows us, for the first time, to improve image compression rates using context-based scans. The results presented in this paper greatly improve upon previous work in both compression rate and running time