PhD Thesis

Uwe Rauschenbach: Bedarfsgesteuerte Bildübertragung mit Regions of Interest und Levels of Detail für mobile Umgebungen . Dissertation, Universität Rostock, Ingenieurwissenschaftliche Fakultät, 5. Mai 2000.

Translated Title

Demand-driven image transmission using regions of interest and levels of detail for mobile environments. PhD thesis, University of Rostock, Faculty of Engineering, 5 May 2000.

Translated Abstract

With the increasing popularity of mobile computers and GSM-based data transmission devices, the transmission and presentation of raster images gains increasing importance also in mobile environments. In these environments, low transmission bandwidth and small displays are limiting factors for the transfer and presentation of large images.

This thesis proposes a formal model for the demand-driven image transmission, which allows to describe arbitrary regions in the image (so called regions of interest - RoI) and the required level of detail (LoD) for each of theses RoIs. A RoI can be defined by the user before starting the image transmission as well as during the process of transmitting an image; necessary refinement data are transmitted free of redundancy even if RoIs overlap. Founded on the model, a wavelet-based coding and transmission scheme has been realized which uses a novel wavelet decomposition scheme.

Several demand-driven image transmission applications are presented as examples. A system for the support of the user roles "image author" and "image viewer" and the newly developed focus and context technique "RECTANGULAR FISH EYE VIEW" are described in detail. The fish eye technique allows the combined transmission and presentation of large raster images in mobile environments, using the available screen space and transmission bandwidth efficiently.

For the special class of palettized images, a new encoding method has been developed which uses progressive refinement of the number of colors during transmission. Compared to the standard methods interlaced GIF and interlaced PNG, the new method allows the recognition of fine details earlier in the course of transmission while delivering a superior or similar compression ratio.

Further Information

My PhD thesis has been written in German. The main ideas are covered by the following English publications.