Daan M. Zwick

RMS Granularity: Determination of Just-Noticeable Differences

Just-noticeable differences (JND) in terms of rms granularity (σ D ) have been determined for color film images. Dependence of the JND on scene complexity, magnification, and mode of picture presentation has been studied. While the JND value of 6% has been confirmed for the case of a uniform area, a change in σ D of the order of 15% is a JND for an “average” picture. These data apply equally well to still and motion pictures, and probably also to television display of film.

A Survey of Telecine Practices: A Report of the Telecine Subcommittee of the Ad Hoc Committee for Color Television Study

In connection with a comprehensive study of causes of variability in the color of television pictures, being conducted by an ad hoc committee (AHCCTS) of a joint industry committee (JCIC), a subcommittee has been investigating the contribution of telecine equipment and practices to the problem. The investigation has included detailed examination by subcommittee members of particular telecine operations and the preparation of videotape transfers from a common motion-picture film print at several telecine installations. In addition, a questionnaire was sent to broadcasters to obtain information on equipment in use, operating procedures, and attitudes toward the telecine operation. — This paper reports the results of this work to date. The conclusion is drawn that the telecine operation is a significant source of television picture variation, independent of and adding directly to the variation usually attributed to the film input itself.

The Meaning of Numbers to Photographic Parameters

A major function of the photographic instrumentation engineer is to reduce phenomena to numbers, so he can measure, analyze, and manipulate. Photographic materials, e.g., films and papers, are part of his instrumentation. The purpose of this paper is to help the engineer, and others, understand that numbers can be assigned to characteristics of photographic materials, and what worth such numbers can have. The numbers discussed are those associated with sensitometry (speed, contrast, gamma, latitude) and especially those associated with image structure (RMS granularity, and modulation transfer function). Both color and black-and-white films are considered.