Introduction

Abstract

It is possible to take the view that ever since it began, the “ancient” branch of physics known as Optics has been concerned with processing images. But since the Nineteen-Thirties increasingly close ties have been forming between Optics, which until then had been largely based on instruments, and the sciences of communication and information arising out of mathematics and electronics. Such developments follow naturally, since communication systems and image-forming systems are all designed to receive or transmit information. Furthermore the same mathematical forms are used for describing the behaviour of electrical and optical systems. It is a question of systems theory, particularly linear systems, and of Fourier’s analysis methods, which together constitute an important part of Signal Theory.