Assignment of observations to categories using measured features and a statistical rule. In geological remote sensing, features can be multispectral pixel values or derived spectral reflectance ratios; known field samples provide training labels and independent observations assess errors. Classification boundaries need not coincide with lithological contacts when illumination or cover dominates the signal.
For a binary classifier, the conditional probability of the target condition given a positive classification. If its base rate is , its true-positive probability is , and its false-positive probability is , Bayes' theorem gives . The denominator is positive whenever a positive classification can occur.
