A method of processing graphical image data representing optically scanned medication-related units may include receiving image data generated responsive to disposal of the units on a tray disposed a distance from an image acquisition component, the image data including data indicative of visually observable features of the units disposed on the tray. The method further includes comparing at least two features among the visually observable features from the image data to reference data indicative of corresponding features of reference units. The reference data is selected for comparison based on an identification of the reference data as corresponding to a prescription being processed. The reference data includes data indicative of features of the reference units extracted from images captured using hardware corresponding to hardware used to generate the image data. The method further includes generating a likelihood rating for each of the at least two features based on the comparing.