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Approximating binary images from discrete X-rays. (English) Zbl 0987.05037

Summary: We study the problem of approximating binary images that are accessible only through few evaluations of their discrete X-ray transform, i.e., through their projections counted with multiplicity along some lines. This inverse discrete problem belongs to a class of generalized set partitioning problems and allows natural packing and covering relaxations. For these (NP-hard) optimization problems we present various approximation algorithms and provide estimates for their worst-case performance. Further, we report on computational results for various variants of these algorithms. In particular, the corresponding integer programs are solved with only small absolute error for instances up to \(250,000\) binary variables.

MSC:

05B40 Combinatorial aspects of packing and covering
68U10 Computing methodologies for image processing
05C70 Edge subsets with special properties (factorization, matching, partitioning, covering and packing, etc.)
68R05 Combinatorics in computer science
82D25 Statistical mechanics of crystals
90C27 Combinatorial optimization
92C55 Biomedical imaging and signal processing
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