scan line - technical definition

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 total
       PAL/SECAM           580 out of 625 total

       Digital             Active
       Formats             Scan Lines
       DVD                 480
       DV                  480
       SDTV Digital TV     480
       EDTV Digital TV     480
       HDTV Digital TV     720 & 1080