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525-line (orEIA 525/60) is an Americanstandard-definition television resolution used since July 1, 1941,[1][2][3] mainly in the context of analog TV broadcast systems. It consists of a 525-lineraster, with 486 lines carrying the visible image at 30 (29.97 with color)interlacedframes per second. It was eventually adopted by countries using 60 Hzutility frequency as TV broadcasts resumed after World War II. With the introduction of color television in the 1950s,[4] it became associated with theNTSC analog color standard.
The system was given their letter designation asCCIR System M in theITU identification scheme adopted in Stockholm in 1961.
A similar625-line system was adopted by countries using a 50 Hz utility frequency. Other systems, like375-line,405-line,441-line and819-line existed, but became outdated or had limited adoption.
The modern standard-definitiondigital video resolution480i is equivalent to 525-line and can be used todigitize a TV signal, or playback generating a 525-line compatible analog signal.[5]
The followingInternational Telecommunication Unionstandards use 525-lines:
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The followinganalog television color systems were used in conjunction with the previous standards (identified by a letter after the color system indication):
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525-lines is sometimes mentioned when digitizing analog video, or when outputting digital video in a standard definition analog compatible format.