Recursive image subsampling which yields support areas approaching fractals is described and analyzed using iterated function systems. The subsampling scheme is suitable in, e.g., hierarchical image processing and image coding schemes. For hexagonally sampled images a hierarchical subsampling structure is given which yields hexagon-like regions with fractal borders.

This paper presents a review of promising techniques for very low bit-rate, below 64 kb/s, image sequence coding. Image sequence coding at such low rates will be a crucial technique in forthcoming visual services, e.g., visual information transmission and storage. A typical application is to transmit moving videophone scenes through the existing analog telephone lines or via a mobile channel. Two types of potential coding techniques are addressed: waveform-based image sequence coding and model-based image sequence coding.