JournalTOCs

Image Analysis & Stereology
Journal Prestige (SJR): 0.689

Citation Impact (citeScore): 2
Number of Followers: 1

This is an Open Access Journal

Open Access journal
ISSN (Print) 1580-3139 - ISSN (Online) 1854-5165
Published by International Society for Stereology and Image Analysis

[1 journal]

Defining and applying a new approximation for the parametric probability
densities of spherical particle profile sizes
- Authors: Ekaterina Poliakova
  Abstract: A novel approximation for the parametric probability densities of spherical particle profile diameters is suggested. The spheres are approximated from solids obtained by rotating regular polygons around their axes of symmetry. This approximation facilitates using the maximum likelihood method in samples that have too few profiles for applying classical stereological approaches.
  PubDate: 2022-04-08
  DOI: 10.5566/ias.2539
  Issue No: Vol. 41, No. 1 (2022)
On optimization of active contour methods in colonoscopy image
segmentation
- Authors: Raneem Ismail, Szilvia Nagy
  Abstract: As colonoscopy is the standard screening approach for colorectal polyps, and the first step of the correct classification and the efficient automatic diagnostics is the accurate detection and segmentation of the existing polyps, it is worth researching systematically, how colonoscopy databases are responding to two of the most influential variational segmentation methods, the geodesic and Chan–Vese active contour methods. Due to the quality variation of the colonoscopy databases, pre-processing steps are made. Then, 14 various filtered images are evaluated as different inputs for the active contour methods using the Sørensen–Dice Similarity Coefficient as a performance measurement metric. The effects of the initial mask shape and its size together with the number of iterations, contraction bias and smoothness factor were studied. The number of necessary iterations depended on the image resolution. In general, the Chan-Vese method showed more efficiency to match the actual contour of the polyp than the geodesic one with an initial mask possibly located within the polyp area. Preprocessing such as reflection removal, background subtraction and mean or median filtering improve the Sørensen–Dice coefficient can improve by 0.3.
  PubDate: 2022-04-08
  DOI: 10.5566/ias.2604
  Issue No: Vol. 41, No. 1 (2022)
Statistical assessment of stress redistribution in loaded polycrystals
- Authors: Iva Karafiátová, Zbyněk Pawlas, Luděk Heller
  Abstract: This work deals with the analysis of stress redistribution in a polycrystal due to external loading, anisotropy of elastic properties, and microstructure characteristics. A statistical method that enables assessing relationships between stress fields and microstructure features of interest is suggested. The notion of generalised semivariogram is introduced and used to determine the extent of spatial dependence in multivariate random fields. Afterwards, it is allowed to perform the tests of independence based on the distance correlation coefficient. The detected non-spatial dependencies are further examined, focusing on the identification of the actual type of heteroscedasticity. The method is aimed at analysing large computational datasets resulting from numerical simulations of stress redistribution in polycrystals under external loads. It is demonstrated on datasets computed on a realistic microstructure of a NiTi wire subjected to tension while considering uniform and preferential lattice orientation distributions and various degrees of elastic anisotropy. The method shows for the considered microstructure and loading that the degree of elastic anisotropy does not affect the dependencies contrarily to the lattice orientation distribution.
  PubDate: 2022-04-08
  DOI: 10.5566/ias.2642
  Issue No: Vol. 41, No. 1 (2022)
ADAPTIVE MORPHOLOGICAL FRAMEWORK FOR 3D DIRECTIONAL FILTERING
- Authors: Tin Barisin, Katja Schladitz, Claudia Redenbach, Michael Godehardt
  Abstract: Engineering materials often feature lower dimensional and directed structures such as cracks, fibers, or closed
  facets in foams. The characterization of such structures in 3D is of particular interest in various applications in
  materials science. In image processing, knowledge of the local structure orientation can be used for structure
  enhancement, directional filtering, segmentation, or separation of interacting structures. The idea of using
  banks of directed structuring elements or filters parameterized by a discrete subset of the orientation space is
  proven to be effective for these tasks in 2D. However, this class of methods is prohibitive in 3D due to the high
  computational burden of filtering on a sufficiently fine discretization of the unit sphere.
  This paper introduces a method for 3D pixel-wise orientation estimation and directional filtering inspired
  by the idea of adaptive refinement in discretized settings. Furthermore, an operator for distinction between
  isotropic and anisotropic structures is defined based on our method. This operator utilizes orientation
  information to successfully preserve structures with one or two dominant dimensions. Finally, feasibility
  and effectiveness of the method are demonstrated on 3D micro-computed tomography images in three use
  cases: detection of a misaligned region in a fiber-reinforced material, crack detection in concrete, and facet
  detection in partially closed foams.
  PubDate: 2022-04-08
  DOI: 10.5566/ias.2639
  Issue No: Vol. 41, No. 1 (2022)