HDTV AND FILM - ISSUES OF VIDEO SIGNAL DYNAMIC-RANGE

The SMPTE Working Group on High-Definition Electronic Production (WG-HDEP) developed the basis of an HDTV production standard from 1984 to 1987. In September 1988, the SMPTE formally standardized 1125/60 HDTV studio origination format, now well known as the SMPTE 240M standard. Since that time the work of the WG-HDEP has continued unabated. Prominent among the group's activities have been rigorous development of the digital representation of SMPTE 240M and a broad examination of image transfer of an HDTV production standard to 35mm film (and vice versa). In the digital work the issue of signal dynamic range emerged early as a major topic of study. The desire to better reconcile HDTV image capture with that of film (particularly if intercutting is under consideration), coupled with more efficient use of digital encoding, called for a closer look at the total transfer characteristic of the HDTV camera and how it should be preserved throughout the total system. This article is intended to describe, in tutorial form, some of the new thinking that is emerging on HDTV video dynamic range and how it relates to the perhaps better-known contrast handling capability of motion-picture film negative.