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Definition: scan line

A horizontal line (a row) in a video frame. Camcorders sense image frames a line at a time, and display systems create images a line at a time. The scan lines are the vertical resolution of the system; for example, an NTSC TV signal uses 525 lines, 480 of which contain image data ("active" scan lines) and 45 are the vertical blanking interval (VBI) in between the frames. Following are the active scan lines of various video formats. See scan rate and horizontal scan frequency.

  Analog              Active
  Formats             Scan Lines

  VHS                 240
  8mm                 240
  Sony U-matic 3/4"   250
  Sony U-matic SP     330
  S-VHS               400
  Hi8                 400
  Laserdisc           425
  NTSC                480 out of 525
  PAL/SECAM           580 out of 625

  Digital             Active
  Formats             Scan Lines

  DVD                 480
  DV                  480
  SDTV Digital TV     480
  EDTV Digital TV     480
  HDTV Digital TV     720 & 1080