AbstractIn a study of intersterility groups in the genusArmillaria, a scanning stage microscope photometer was used to obtain digitized images of photographs of isoelectric focusing patterns. Absorbance values were then mapped from the metric scale to the pH scale. Absorbance values in specified pH intervals were used as features in multivariate statistical procedures to characterize populations and to assign isolates to populations. Digital image analysis techniques were used to obtain an enhanced image of faint or poorly resolved bands.