title: Comparative evaluation of autofocus algorithms for a real-time system for automatic detection of Mycobacterium tuberculosis.
abstract: Microscopy images must be acquired at the optimal focal plane for the objects of interest in a scene. Although manual focusing is a standard task for a trained observer, automatic systems often fail to properly find the focal plane under different microscope imaging modalities such as bright field microscopy or phase contrast microscopy. This article assesses several autofocus algorithms applied in the study of fluorescence-labeled tuberculosis bacteria. The goal of this work was to find the optimal algorithm in order to build an automatic real-time system for diagnosing sputum smear samples, where both accuracy and computational time are important. We analyzed 13 focusing methods, ranging from well-known algorithms to the most recently proposed functions. We took into consideration criteria that are inherent to the autofocus function, such as accuracy, computational cost, and robustness to noise and to illumination changes. We also analyzed the additional benefit provided by preprocessing techniques based on morphological operators and image projection profiling.
authors.affiliation: CIBERSAM, Madrid, Spain. jmmateos@mce.hggm.es
authors.forename: José María
authors.initials: JM
authors.lastname: Mateos-Pérez
authors.forename: Rafael
authors.initials: R
authors.lastname: Redondo
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Nava
authors.forename: Juan C
authors.initials: JC
authors.lastname: Valdiviezo
authors.forename: Gabriel
authors.initials: G
authors.lastname: Cristóbal
authors.forename: Boris
authors.initials: B
authors.lastname: Escalante-Ramírez
authors.forename: María Jesús
authors.initials: MJ
authors.lastname: Ruiz-Serrano
authors.forename: Javier
authors.initials: J
authors.lastname: Pascau
authors.forename: Manuel
authors.initials: M
authors.lastname: Desco
mesh_terms: D000465:Algorithms; D006801:Humans; D008853:Microscopy / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D010363:Pattern Recognition, Automated / Q000379:methods*; D013183:Sputum / Q000382:microbiology; D014376:Tuberculosis / Q000175:diagnosis*