Values represent the proportion of images in the test set given a classification specified by columns, on average for the top 25 algorithms. The reference row of each group shows the aggregate values for each diagnosis. Subsequent rows include stratifications across artifacts (ie, crust, hair, pen marks), anatomical site, and source institution. Upper extremity refers to arms and feet (not palms or soles). Lower extremity refers to legs (not palms or soles). AK=actinic keratosis. BCC=basal cell carcinoma. BCN=Hospital Clinic Barcelona. BKL=benign keratosis. DF=dermatofibroma. HAM=Medical University of Vienna. MEL=melanoma. NT=not trained. NV=nevi. SCC=squamous cell carcinoma. VASC=vascular lesion.