Efficient and Robust Path Openings Using the Scale-Invariant Rank Operator

Gronde, Jasper J. van de; Offringa, A. R.; Roerdink, Jos B. T. M.

doi:10.1007/s10851-016-0649-5

Cited by 7 publications

(7 citation statements)

References 27 publications

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“…This process highlights curvilinear structures which can henceforth be ltered by path openings. Similar procedures have been used as a preprocessing step for path openings in other works as well [4,6,11].…”

Section: Openingsmentioning

confidence: 99%

Fast Computation of Greyscale Path Openings

Gronde

Schubert

Roerdink

2015

Lecture Notes in Computer Science

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Path openings are morphological operators that are used to preserve long, thin, and curved structures in images. They have the ability to adapt to local image structures, which allows them to detect lines that are not perfectly straight. They are applicable in extracting cracks, roads, and similar structures. Although path openings are very e cient to implement for binary images, the greyscale case is more problematic. This study provides an analysis of the main existing greyscale algorithm, and shows that although its time complexity can be quadratic in the number of pixels, this is optimal in terms of the output (if the full opening transform is created). Also, it is shown that under many circumstances the worst-case running time is much less than quadratic. Finally, a new algorithm is provided, which has the same time complexity, but is simpler, faster in practice and more amenable to parallelization

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Section: Openingsmentioning

confidence: 99%

Fast Computation of Greyscale Path Openings

Gronde

Schubert

Roerdink

2015

Lecture Notes in Computer Science

Self Cite

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show abstract

Section: Openingsmentioning

confidence: 99%

Efficient Computation of Greyscale Path Openings

Schubert

Gronde

Roerdink

2016

Mathematical Morphology - Theory and Applications

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Path openings are morphological operators that are used to preserve long, thin, and curved structures in images. They have the ability to adapt to local image structures,which allows them to detect lines that are not perfectly straight. They are applicable in extracting cracks, roads, and similar structures. Although path openings are very efficient to implement for binary images, the greyscale case is more problematic. This study provides an analysis of the main existing greyscale algorithm, and shows that although its time complexity can be quadratic in the number of pixels, this is optimal in terms of the output (if the full opening transform is created). Also, it is shown that under many circumstances the worst-case running time is much less than quadratic. Finally, a new algorithm is provided,which has the same time complexity, but is simpler, faster in practice and more amenable to parallelization

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“…Therefore, the algorithm is suitable for real-time use, where we are limited by the number of compute cycles we can spend. The scale-invariant rank operator [2] makes SumThreshold more robust, by extending the ranges of flagged samples by a percentage of the size of the flagged range. A typical percentage we used is 20%.…”

Section: The Sumthreshold Algorithmmentioning

confidence: 99%

“…We use a version of the SIR operator implementation that has a linear computational complexity in the number of samples (the original implementation in the AOFlagger had worse computational complexity). The linear version of the algorithm is described in [2]. Since SIR operates on the flag masks only, and not on the actual data itself, it is extremely efficient.…”

Section: The Scale-invariant Rank Operatormentioning

confidence: 99%

See 1 more Smart Citation

Towards exascale real-time RFI mitigation

Nieuwpoort

2016

2016 Radio Frequency Interference (RFI)

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We describe the design and implementation of an extremely scalable real-time RFI mitigation method, based on the offline AOFlagger. All algorithms scale linearly in the number of samples. We describe how we implemented the flagger in the LOFAR real-time pipeline, on both CPUs and GPUs. Additionally, we introduce a novel simple history-based flagger that helps reduce the impact of our small window on the data.By examining an observation of a known pulsar, we demonstrate that our flagger can achieve much higher quality than a simple thresholder, even when running in real time, on a distributed system. The flagger works on visibility data, but also on raw voltages, and beam formed data. The algorithms are scale-invariant, and work on microsecond to second time scales. We are currently implementing a prototype for the time domain pipeline of the SKA central signal processor.

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Efficient and Robust Path Openings Using the Scale-Invariant Rank Operator

Cited by 7 publications

References 27 publications

Fast Computation of Greyscale Path Openings

Fast Computation of Greyscale Path Openings

Efficient Computation of Greyscale Path Openings

Towards exascale real-time RFI mitigation

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