title: Evaluation of autofocus algorithms for tuberculosis microscopy.
abstract: Direct sputum smear microscopy is the most cost-effective method of screening suspected cases of tuberculosis (TB) in high-prevalence countries. Automated microscopy of sputum smears to detect TB would enable rapid screening of large numbers of samples. We evaluate autofocus algorithms for TB microscopy as a step in the development of an automated microscope. Three different focus measures (namely the energy of the image Laplacian, the variance of the log-histogram and the first order Gaussian derivative) are tested on sequences of images of sputum smear slides with varying degrees of content density. A combination of search methods is applied in conjunction with the focus measure to find the position of optimal focus.
authors.affiliation: Department of Electrical Engineering, University of the Witwatersrand.
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Russell
authors.forename: Tania S
authors.initials: TS
authors.lastname: Douglas
mesh_terms: D000465:Algorithms; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012371:Robotics / Q000295:instrumentation / Q000379:methods; D012680:Sensitivity and Specificity; D014376:Tuberculosis / Q000473:pathology*