Influence of the phase effect on gradient-based and statistics-based focus measures in bright field microscopy

Journal article


Publication Details

Author(s): Schöll S, Mualla F, Sommerfeldt B, Steidl S, Maier A, Buchholz R, Hornegger J
Journal: Journal of Microscopy
Publisher: Wiley-Blackwell
Publication year: 2014
Volume: 254
Journal issue: 2
Pages range: 65-74
ISSN: 0022-2720
eISSN: 1365-2818


Abstract


Autofocusing is essential to high throughput microscopy and live cell imaging and requires reliable focus measures. Phase objects such as separated single Chinese hamster ovary cells are almost invisible at the optical focus position in bright field microscopy images. Because of the phase effect, defocused images of phase objects have more contrast. In this paper, we show that widely used focus measures exhibit an untypical behaviour for such images. In the case of homogeneous cells, that is, when most cells tend to lie in the same focal plane, both gradient-based and statistics-based focus measures tend to have a local minimum instead of a global maximum at the optical focus position. On the other hand, if images show inhomogeneous cells, gradient-based focus measures tend to yield typical focus curves, whereas statistics-based focus measures deliver curves similar to the case of homogeneous cells. These results were interpreted using the equation describing the phase effect and patch-wise analysis of the focus curves. Bioprocess engineering experts are also influenced by the phase effect. Forty-four focus positions selected by them led to the conclusion that they prefer to look at defocused images instead of those at the optical focus. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.



FAU Authors / FAU Editors

Buchholz, Rainer Prof. Dr.
Lehrstuhl für Bioverfahrenstechnik
Hornegger, Joachim Prof. Dr.-Ing.
Lehrstuhl für Informatik 5 (Mustererkennung)
Maier, Andreas Prof. Dr.-Ing.
Lehrstuhl für Informatik 5 (Mustererkennung)
Mualla, Firas
Lehrstuhl für Informatik 5 (Mustererkennung)
Schöll, Simon
Lehrstuhl für Informatik 5 (Mustererkennung)
Sommerfeldt, Björn
Lehrstuhl für Bioverfahrenstechnik
Steidl, Stefan PD Dr.-Ing.
Lehrstuhl für Informatik 5 (Mustererkennung)


How to cite

APA:
Schöll, S., Mualla, F., Sommerfeldt, B., Steidl, S., Maier, A., Buchholz, R., & Hornegger, J. (2014). Influence of the phase effect on gradient-based and statistics-based focus measures in bright field microscopy. Journal of Microscopy-Oxford, 254(2), 65-74. https://dx.doi.org/10.1111/jmi.12118

MLA:
Schöll, Simon, et al. "Influence of the phase effect on gradient-based and statistics-based focus measures in bright field microscopy." Journal of Microscopy-Oxford 254.2 (2014): 65-74.

BibTeX: 

Last updated on 2018-19-04 at 02:44