Standard Setting in High-Definition Television

TODAYTELEVISION SIGNALS are encoded, broadcast, and received in the United States using the color system of the National Television Systems Committee (NTSC). Almost 40 years old, this system has well-known performance limitations. It is subject to flickering and ghosting, it has low resolution (more apparent as TV sets become larger), and it requires cutting off the side panels in showing material shot for exhibition on wide movie screens. NTSC is derisively known in some circles as "Never Twice the Same Color." Although it nominally has 525 horizontal lines, a mere 483 "active" lines produce the picture; the rest carry auxiliary information. Moreover, NTSC is interlaced: only half of the lines are displayed on each pass. This creates a visible flicker when there are horizontal lines in the scene portrayed, so studios deliberately reduce the resolution. Even with ideal reception, the resolution is roughly equivalent to that achievable with 330 to 350 lines. The PAL and SECAM standards are significantly better, but still noticeably imperfect. Developed about 15 years later than NTSC, they are used in much of the world outside North America and Japan.