Multiresolution-based storage, browsing and retrieval for digital image libraries
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In this dissertation, the focus is on algorithms for progressive-resolution image transmission, storage and retrieval. The resulting methods are designed to support a fast system response, to provide an intuitive image representation, and to achieve lossless image compression at competitive bit rates.
Average interpolation subdivision (AIS) is introduced. It offers a sound mathematical framework for the derivation of algorithms providing the functionality required. To proceed from AIS to image compression, a multiresolution analysis is added. It allows the construction of wavelet transforms and leads to AIS filter banks.
For lossless image compression, reversible wavelet transforms (RWTs) are constructed. To that end, an interband prediction structure for AIS filter banks is first derived. Afterwards rounding operations are introduced, and RWTs are assembled. Reversible AIS filter banks deliver acceptable bit rates when applied to the lossless compression of monochrome images. A time-domain filter analysis confirms that AIS filters are nearly optimal given their structural constraints. Better results are still obtainable. They, however, require an enhanced interband prediction framework.
If images of arbitrary size are to be ingested into a database, an efficient method is needed to process signal boundaries. It is demonstrated that interband-prediction offers an elegant and practical solution for this task.
The reversible AIS filter banks are finally applied to the lossless compression of color images. Color images offer an excellent opportunity for the design of algorithms which are applicable to a much wider range of multispectral imagery. A new lossless compression method is proposed. It executes a reversible wavelet transform first and then applies adaptive spectral transforms to associated color subbands. Very good results have been obtained. Yet, little computational complexity has been added. Simulation results are included. They verify the rationale of this approach.