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Development and evaluation of passive autofocus algorithms in the field of automated microscopy

: Erpenbeck, Daniel; Wittenberg, Thomas; Münzenmayer, Christian; Benz, Michaela


Biomedizinische Technik 59 (2014), No.s1, pp.559-562
ISSN: 0013-5585
ISSN: 1862-278X
Deutsche Gesellschaft für Biomedizinische Technik (DGBMT Jahrestagung) <48, 2014, Hannover>
Journal Article, Conference Paper
Fraunhofer IIS ()
Zytologie; medizinische BV; Hämatologie; Farbbilder; Computer Assistierte Mikroskopie; Anwendungen BV; Algorithmen

This paper presents a comparison of different focus functions applied to microscopic images of blood smears. At the beginning of the article, standard methods for calculating the sharpness of an image are presented. In addition, these methods which are typically based on calculations for grayscale images are extended to the analysis of color images. Furthermore, the influence of calculating these metrics on small "Region of Interests" (ROI) instead of considering the whole image is investigated. For evaluating the results, the focus curves of several focus stacks have been analyzed. Therefore, some criteria for describing the quality of a focus curve are introduced as well. The evaluation shows, that especially in the far focus area the performance of sharpness calculations can be improved by considering color aspects. Furthermore, the choice of selected ROIs is confirmed by the acceleration of these calculations without loss of information.