For decades scientists have been conducting research to determine the ideal television image. They have concluded that a television system with 1,500 scanning lines would improve picture resolution more than three-fold over the standard 25-inch monitor/ receiver television picture. High definition television (HDTV) is a key development which will affect television and movie viewing in the future. In contrast to current television standards of 525 scanning lines, HDTV utilizes 1,000, 1,550, and even 2,000 scanning lines. The doubling of resolution creates an image five to ten times as detailed as that available on current television receivers. HDTV also provides the potential to increase screen size by as much as 25 percent without additional distortion.
The standard HDTV produces a television picture which provides the same picture quality as 35mm film and shows the average 8 by 11 inch typed page with a clarity that is legible. Unfortunately, the image produced by the 1,000 scan lines, though legible, may be uncomfortable to read for extended periods. Philips, a Dutch electronic conglomerate, is therefore engaged in projects involving the development of screens ranging up to 2,000 scan lines per frame which would display text with the clarity of a printed page.
The basic technology for HDTV already exists; however, cost and regulation are major obstacles to its practical application. Before HDTV can be utilized by the public, the Federal Communications Commission (FCC) would have to allocate new channel space. The broadcast bandwidth needed to accommodate the entire signal would be 30 MHz, the equivalent of five times the present NTSC (National Television Standards Committee) standard.
The wider bandwidth of HDTV would require replacing the present VHF and UHF technologies with satellite distribution or digital transmission using optical fiber or coaxial cable. Images could be sent from satellite to cable companies for distribution or directly to an individual consumer s satellite dish. The signals would have the quality of images of 70mm film or theatre film projection.
Several technical barriers must still be overcome before HDTV becomes reality. For example, broadcasters must invest in new cameras and other studio equipment. In addition, refinements of a high resolution tube, a television projection display system and video recorders are needed. Perhaps the greatest obstacle to the broad application of HDTV is that viewers would also have to replace their television sets and video cassette recording machines.
High-density television could play a dynamic role in the future. Movies might no longer be shot in 35mm or 16mm but with HDTV cameras in video. HDTV would allow editing, production, release, and display- all on videotape. Detail, color, and sound would be better than that achieved with the 16mm or 35mm film. The high-resolution pictures available for video transmission would transform the use of images in such fields as art, botany, zoology, medicine, geology, and physics. In addition, the ability of HDTV to transmit legible text would have an impact on videotext systems.
Videotape applications are likely to become available before HDTV becomes the norm in the broadcasting industry because it will not require FCC action. The first direct broadcast satellite may not be launched until 1986. CBS is presently studying the possibility of achieving a higher quality image by transmitting HDTV through two channels simultaneously. Consumers could achieve a high definition picture by tuning into both channels at once or by purchasing an upgraded television set. This would ease the entry into the new technology.
There will also be a gradual change-over to digital television receivers, which use semiconductor chips to convert broadcast signals into digital code.
Digital TV also provides better picture quality. Sony, Panasonic and Quasar are currently developing this capability and expect its widespread adoption to coincide with the emergence of HDTV.
