Digital techniques in film scanning

Over the last few years there have been dramatic changes in the design of telecine. These have been made possible by advances in semiconductor technology. The paper discusses the problems of transferring film to television, and describes the earlier type of flying spot telecine. The potential impairments, particularly in terms of shading and focus interlace flicker effects are discussed. The first of the modern telecines was a jump scan system, and this is described with some discussion of the problems of operating this system on 60Hz TV field rate systems. The sequential scanning system, made possible by the use of digital storage is then considered, and a description is given of this system when applied to a flying spot scanner. The advent of suitable linear array sensors has made it possible to design a completely new type of telecine. This type of telecine is described. Analogue signal processing for telecine is difficult because of the high contrast range and high degree of nonlinear correction required. A totally digital approach to signal processing for telecine is now possible, and a description of such a system is given. Mention is made of the use of microprocessors and digital techniques in the design of the film transport mechanism, and there is a brief outline of some possible future developments.