Testing Connectedness of Images

We investigate algorithms for testing whether an image is connected. Given a proximity parameter ϵ ∈ ( 0 , 1 ) and query access to a black-and-white image represented by an n × n matrix of Boolean pixel values, a (1-sided error) connectedness tester accepts if the image is connected and rejects with...

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Bibliographic Details
Published in:Algorithmica Vol. 86; no. 11; pp. 3496 - 3517
Main Authors: Berman, Piotr, Murzabulatov, Meiram, Raskhodnikova, Sofya, Ristache, Dragos-Florian
Format: Journal Article
Language:English
Published: New York Springer US 01.11.2024
Springer Nature B.V
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ISSN:0178-4617, 1432-0541
Online Access:Get full text
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Summary:We investigate algorithms for testing whether an image is connected. Given a proximity parameter ϵ ∈ ( 0 , 1 ) and query access to a black-and-white image represented by an n × n matrix of Boolean pixel values, a (1-sided error) connectedness tester accepts if the image is connected and rejects with probability at least 2/3 if the image is ϵ -far from connected. We show that connectedness can be tested nonadaptively with O ( 1 ϵ 2 ) queries and adaptively with O ( 1 ϵ 3 / 2 log 1 ϵ ) queries. The best connectedness tester to date, by Berman, Raskhodnikova, and Yaroslavtsev (STOC 2014) had query complexity O ( 1 ϵ 2 log 1 ϵ ) and was adaptive. We also prove that every nonadaptive, 1-sided error tester for connectedness must make Ω ( 1 ϵ log 1 ϵ ) queries.
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ISSN:0178-4617
1432-0541
DOI:10.1007/s00453-024-01248-x