Until recently digital processing of biomedical images was conducted solely in the research laboratories of the universities and industry. However, with the advent of computerized tomography in 1972 and the computerized white blood cell differential count in 1974, enormous changes have suddenly occurred. Digital image pro- cessing in biomedicine has now become the most active sector in the digital image processing field. Processing rates have reached the level of one trillion picture elements per year in the United States alone and are expected to be ten trillion per year in 1980. This...