Interlaced Scanning

VP

To economise bandwidth for CRT monitors, lines of video are recorded as separate fields of odd lines followed by scans of the even lines. Sometimes still frames in interlace scanning produce a flicker. Progressive scanning produces sharper images but requires greater bandwidth.

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WikiV

A technique of combining two television fields in order to produce a full frame. The two fields are composed of only odd and only even lines, which are displayed one after the other but with the physical position of all the lines interleaving each other, hence interlace.[5]

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TV

This process divides and presents each video frame as two fields. Imagine a video frame being divided by the odd and even horizontal lines that make up the picture. The first field presents the odd lines; the second field represents the even lines. The fields are aligned and timed so that, with a still image, the human eye blends the two fields together and sees them as one. Motion in the image makes the fields noticeable. Interlace scanning allows only half the lines to be transmitted and presented at any given moment.