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Optical Engineering

Fast autofocus algorithm for automated microscopes
Author(s): Mario Alonso Bueno-Ibarra; Josué Álvarez-Borrego; Leonardo Acho; María Cristína Chávez-Sánchez
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Paper Abstract

We present a new algorithm to determine, quickly and accurately, the best-in-focus image of biological particles. The algorithm is based on a one-dimensional Fourier transform and on the Pearson correlation for automated microscopes along the Z axis. We captured a set of several images at different Z distances from a biological sample. The algorithm uses the Fourier transform to obtain and extract the image frequency content of a vector pattern previously specified to be sought in each captured image; comparing these frequency vectors with the frequency vector of a reference image (usually the first image that we capture or the most out-of-focus image), we find the best-in-focus image via the Pearson correlation. Numerical experimental results show the algorithm has a fast response for finding the best-in-focus image among the captured images, compared with related autofocus techniques presented in the past. The algorithm can be implemented in real-time systems with fast response, accuracy, and robustness; it can be used to get focused images in bright and dark fields; and it offers the prospect of being extended to include fusion techniques to construct multifocus final images.

Paper Details

Date Published: 1 June 2005
PDF: 8 pages
Opt. Eng. 44(6) 063601 doi: 10.1117/1.1925119
Published in: Optical Engineering Volume 44, Issue 6
Show Author Affiliations
Mario Alonso Bueno-Ibarra, Ctr. de Investigación Científica y de Educación Superior de Ensenada (United States)
Josué Álvarez-Borrego, Ctr. de Investigación Científica y de Educación Superior de Ensenada (Mexico)
Leonardo Acho, Ctr. de Investigación y Desarrollo de Tecnología Digital (United States)
María Cristína Chávez-Sánchez, Ctr. de Investigación en Alimentación y Desarrollo, A.C. (Mexico)

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