dc.date.accessioned | 2013-03-12T08:14:22Z | |
dc.date.available | 2013-03-12T08:14:22Z | |
dc.date.issued | 2003 | en_US |
dc.date.submitted | 2004-02-24 | en_US |
dc.identifier.citation | Jensen, Are Fritz Charles. The General Flow-Adaptive Filter. Hovedoppgave, University of Oslo, 2003 | en_US |
dc.identifier.uri | http://hdl.handle.net/10852/9112 | |
dc.description.abstract | While image filtering is limited to two dimensions, the filtering of image sequences can utilize three dimensions; two spatial and one temporal. Unfortunately, simple extensions of common two-dimensional filters into three dimensions yield undesirable motion blurring of the images. This thesis addresses this problem and introduces a novel filtering approach termed the general flow-adaptive filter.
Most often a three-dimensional filter can be visualized as a cubic lattice shifted over the data, and at each point the element corresponding to the central coordinate is replaced with a new value based entirely on the values inside the lattice. The general principle of the flow-adaptive approach is to spatially adapt the entire filter lattice to possibly complex spatial movements in the temporal domain by incorporating local flow-field estimates.
Results using the flow-adaptive technique on five filters the temporal discontinuity filter, a tensor-based adaptive filter, the average, the median and a Gaussianshaped convolution filter are presented. Both ultrasound image sequences and synthetic data sets were filtered. An edge-adaptive normalized mean-squared error is used as performance metric on the filtered synthetic sets, and the error is shown to be substantially reduced using the flow-adaptive technique, as much as halved in many instances. There are even indications that simple Gaussian-shaped convolution filters can outperform larger and more complex adaptive filters by implementing the flow-adaptive procedure. For the ultrasound image sequences, the filters adopting the flow-adaptive principles had outputs with less motion blur and sharper contrast compared to the outputs of the non-flow-adaptive filters.
At the cost of flow estimation, the flow-adaptive approach substantially improves the performance of all the filters included in this study. | nor |
dc.language.iso | eng | en_US |
dc.title | The General Flow-Adaptive Filter : With Applications to Ultrasound Image Sequences | en_US |
dc.type | Master thesis | en_US |
dc.date.updated | 2004-07-02 | en_US |
dc.creator.author | Jensen, Are Fritz Charles | en_US |
dc.subject.nsi | VDP::420 | en_US |
dc.identifier.bibliographiccitation | info:ofi/fmt:kev:mtx:ctx&ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft.au=Jensen, Are Fritz Charles&rft.title=The General Flow-Adaptive Filter&rft.inst=University of Oslo&rft.date=2003&rft.degree=Hovedoppgave | en_US |
dc.identifier.urn | URN:NBN:no-8232 | en_US |
dc.type.document | Hovedoppgave | en_US |
dc.identifier.duo | 16937 | en_US |
dc.contributor.supervisor | Prof. Fritz Albregtsen and prof. Sverre Holm | en_US |
dc.identifier.bibsys | 040645142 | en_US |
dc.identifier.fulltext | Fulltext https://www.duo.uio.no/bitstream/handle/10852/9112/1/Thesis_Jensen2003.pdf | |