NTSC stands for the National Television System Committee and denotes an analog television standard that dominated broadcast television in the United States and several other regions for much of the 20th century. It defines how a television image is scanned, how color is encoded and how video signals are formatted so that transmitters and receivers interoperate. The system was created in the United States and later adopted, with regional variants, in parts of the Americas, East Asia and the Pacific.
Key characteristics
NTSC specifies an interlaced scanning system with 525 scan lines per frame (typically about 480 visible lines) and a field rate of approximately 60 fields per second, producing about 30 frames per second in progressive terms. Color information is carried on a high-frequency subcarrier and encoded in a way designed to be compatible with existing black-and-white receivers. The color encoding commonly associated with NTSC uses luminance and chrominance components (often referred to by the YIQ model) and a color subcarrier near 3.579545 MHz. Variants and regional implementations exist; for example, Japan used a version often noted as NTSC-J.
History and development
The NTSC standard grew out of early experiments in electronic television and the need for a common format for national broadcasting. Initial monochrome (black-and-white) standards preceded color television; a backward-compatible color system was developed and adopted in the early 1950s to allow color broadcasts while maintaining reception on monochrome sets. Over subsequent decades the basic NTSC signal format remained the reference for analog broadcasts in its service areas.
Geographic use and transition
NTSC was widely used in North America, parts of South America, and in several Asian and Pacific territories. Notable users included Japan, South Korea, Taiwan, Philippines, Hong Kong, Myanmar and various Pacific island broadcasters. Many countries have since migrated from analog NTSC to digital standards (for example ATSC, ISDB-T or DVB-T) during the 2000s and 2010s; the United States completed its primary analog-to-digital transition in 2009.
Uses, limitations and notable facts
NTSC enabled widespread over-the-air television by standardizing signal timing, synchronization and color encoding, which helped the consumer television market and broadcast interoperability. Limitations include susceptibility to color hue shifts and a modest vertical resolution compared with later digital systems; these practical issues inspired colloquial critiques (one joking backronym is "Never The Same Color"). NTSC is often compared with alternate analog systems such as PAL and SECAM, which use different line/frame rates and color encoding approaches and were favored in other parts of the world.