Ht-index for empirical evaluation of the sampled graph-based discrete pulse transform

dc.contributor.authorDe Lancey, Mark
dc.contributor.authorFabris-Rotelli, Inger Nicolette
dc.contributor.emailinger.fabris-rotelli@up.ac.zaen_ZA
dc.date.accessioned2021-08-10T06:42:56Z
dc.date.available2021-08-10T06:42:56Z
dc.date.issued2020-12-08
dc.description.abstractThe Discrete Pulse Transform (DPT) makes use of LULU smoothing to decompose a signal into block pulses. The most recent and effective implementation of the DPT is an algorithm called the Roadmaker’s Pavage, which uses a graph-based algorithm that produces a hierarchical tree of pulses as its final output, shown to have important applications in artificial intelligence and pattern recognition. Even though the Roadmaker’s Pavage is an efficient implementation, the theoretical structure of the DPT results in a slow, deterministic algorithm. This paper examines the use of the spectral domain of graphs and designing graph filter banks to downsample the algorithm. We investigate the extent to which this speeds up the algorithm and allows parallel processing. Converting graph signals to the spectral domain can also be a costly overhead, so methods of estimation for filter banks are examined, as well as the design of a good filter bank that may be reused without needing recalculation. The sampled version requires different hyperparameters in order to reconstruct the same textures of the image as the original algorithm, selected previously either through trial and error (subjective) or grid search (costly) which prevented studying the results on many images effectively. Here an objective and efficient way of deriving similar results between the original Roadmaker’s Pavage and our proposed Filtered Roadmaker’s Pavage is provided. The method makes use of the Ht-index which separates the distribution of information in the graph at scale intervals by recursively calculating averages on decreasing subsections of the scale data stored. This has enabled empirical research using benchmark datasets providing improved results. The results of these empirical tests showed that using the Filtered Roadmaker’s Pavage algorithm consistently runs faster, using less computational resources, while having a positive SSIM (structural similarity) with low variance. This provides an informative and faster approximation to the nonlinear DPT, a property which is not standardly achieveable.en_ZA
dc.description.departmentStatisticsen_ZA
dc.description.librarianam2021en_ZA
dc.description.sponsorshipThe South Africa National Research Foundation and South Africa Medical Research Council.en_ZA
dc.description.urihttp://www.journals.co.za/ej/ejour_comp.htmlen_ZA
dc.identifier.citationDe Lancey, M. and Fabris-Rotelli I. (2020). Ht-index for empirical evaluation of the sampled graph-based Discrete Pulse Transform. South African Computer Journal 32(2), 124–140. https://DOI.org/10.18489/sacj.v32i2.849.en_ZA
dc.identifier.issn2313-7835 (online)
dc.identifier.other1015-7999 (print)
dc.identifier.other10.18489/sacj.v32i2.849
dc.identifier.urihttp://hdl.handle.net/2263/81190
dc.language.isoenen_ZA
dc.publisherComputer Society of South Africaen_ZA
dc.rights© The author(s). Published under a Creative Commons NonCommercial 4.0 License (CC BY-NC 4.0).en_ZA
dc.subjectGraph samplingen_ZA
dc.subjectMultiscaleen_ZA
dc.subjectHt-indexen_ZA
dc.subjectDiscrete pulse transform (DPT)en_ZA
dc.subjectLULU smoothingen_ZA
dc.subjectSpectral domain of graphsen_ZA
dc.subjectAlgorithmen_ZA
dc.subjectGraph filter banksen_ZA
dc.titleHt-index for empirical evaluation of the sampled graph-based discrete pulse transformen_ZA
dc.typeArticleen_ZA

Files

Original bundle

Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
DeLancey_HtIndex_2020.pdf
Size:
1.39 MB
Format:
Adobe Portable Document Format
Description:
Article

License bundle

Now showing 1 - 1 of 1
Loading...
Thumbnail Image
Name:
license.txt
Size:
1.75 KB
Format:
Item-specific license agreed upon to submission
Description: