Several standard series of photographs (Zweigle KG-741, ASTM D3512, EMPA, and JIS L 1076) widely used for pilling evaluation in fabric testing laboratories are analyzed. Common information is extracted from two standard series, the Zweigle and the American Society for Testing and Materials (ASTM) standards, by applying an objective and automatic method of image analysis previously developed for pilling evaluation. The information obtained reveals that both standards approach the same underlying logarithmic function between the total area of pilling and the degree of pilling. Another important feature, the density of pilling, is also extracted and discussed. © 2001 Society of Photo-Optical Instrumentation Engineers.