A comparison of analog and digital techniques for pattern recognition

Since the computer technology utilized often places limitations on the performance of a particular pattern-recognition task, it is important to compare the state-of-the-art and future trends in both the digital and the analog-computer fields. Electronic, acoustical, and optical analog computers for use in pattern recognition are discussed and their performance compared with that of both general-purpose and special-purpose digital computers. It is shown that the analog computer offers workers using low-precision high-speed one-dimensional or two-dimensional linear discriminant analysis a significant advantage in hardware performance (equivalent bits per second per dollar) over the digital computer in certain limited but important areas. These areas include fingerprint identification, word recognition, chromosome spread detection, earth-resources and land-use analysis, and broad-band radar signal processing. A trend analysis is presented which indicates that the advantages of analog computation will probably be overcome in the next few decades by the rapid performance advances being made in digital-computer hardware.