A scanning process in which the distance from centre to centre of successively scanned lines is two or more times the nominal line width, and in which the adjacent lines belong to different fields. For a given number of active vertical lines per frame, and a given frame-rate, interlaced scanning provides system-limited definition for still images. Moving images, however, provide reduced perceived spatial definition.

Although the interlaced scanning field-rate at a multiple of the framerate could improve temporal resolution, this is seldom perceived. When scanning interlaced 2:1 in either capture or display mode, the lines constituting one frame of the image are scanned and/or presented in two successive fields one-half the lines in one field and the other half interleaved as the following field. In a system based upon a nominal 60 Hz, for example, the generation and presentation of the two fields in succession require a total of 1/30 sec per frame, with a continual temporal progression from start to finish of the scanning. Note: Interlaced scanning may be introduced in the original scanning for image capture, or may be developed from progressive scanning of the original.