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In its simplest form, a lower third can just be text overlying the video. Frequently this text is white with a drop shadow to make the words easier to read. A lower third can also contain graphical elements such as boxes, images or shading. Some lower thirds have animated backgrounds and text.
Lower thirds can be created using basic home-video editing software or professional-level equipment. This equipment makes use of video's alpha channel to determine what parts of the graphic or text should be transparent, allowing the video in the background to show through.
Lower thirds are also often known as "CG" or captions, and sometimes chyrons in North America, due to the popularity of Chyron Corporation's Chiron I character generator, an early digital solution developed in the 1970s for rendering lower thirds. Other common terms include superbars (or simply supers) (US), name straps and astons (after Aston Broadcast Systems) (UK).
Video with lower thirds is known as a "program as broadcast" or as "dirty"; video without lower thirds is known as a "clean feed" or as "textless". For international distribution, programs often include "textless elements" on the master tape – these are all the shots to which lower thirds (and other digital on-screen graphics) have been applied, placed end-to-end so a clean master can be created if necessary.
Lower thirds are usually arranged in tiers, or lines:
- One-tier lower thirds: Usually used to identify a story that is being shown, or to show a presenter's name.
- Two-tier lower thirds: Used most often to identify a person on screen. Often, the person's name will appear on the first line, with his or her place of residence or a description below it. Two-tier lower thirds may also be used as "locators" to identify where a story is taking place.
- Three-tier lower thirds: These lower thirds add more information. Commonly, the first tier is used to tell when the video was shot, if it was not shot the day the newscast is airing.