Astrid Lundmark

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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(More)
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(More)
The thesis describes usage and generation of motion information in the field of video coding. Hierarchical structures for computation of this motion information are suggested. These hierarchical structures can be used also for other applications. One part of the motion information consists of vectors indicating the displacement between successive frames in(More)
Hexagonal regions are optimal for subdividing the plane in the sense that the regions are as close as possible to the disk shape while still providing a tessellation of the plane. It is however not possible to do recursive subdivisions, i.e. to divide a hexagon into smaller hexagons. In this paper, hexagon-like fractal regions will be presented. It is(More)
With the success and growth of IP-based networks, like the Internet, demands for real-time applications such as video conferencing and IP-telephony have evolved. However, the current Internet does not provide any Quality-of-Service, which may result in unsatisfactory image/sound quality due to e.g. packet losses. One approach to improve the quality is to(More)