keyers

Keyers, also known as character generators or simply CG, are specialized video production devices or software used to create and superimpose graphics and text onto a video signal. They are essential tools in broadcast television, live event production, and post-production workflows for adding information that would otherwise be absent or difficult to convey.

The primary function of a keyer is to generate or retrieve graphic elements, such as titles, lower thirds (text identifying people or places), logos, weather graphics, or scores, and then "key" them into a video feed. This process involves using an alpha channel, which acts as a transparency mask. Areas defined as opaque in the alpha channel will be displayed, while transparent areas will allow the underlying video signal to show through. This creates a seamless integration of the graphics with the video content.

Keyers can be hardware-based, integrated into video switchers, or exist as standalone units. Alternatively, they can be software-based, running on computers as part of video editing suites or dedicated graphics applications. Modern keyers often offer sophisticated features, including real-time animation, 3D rendering, and integration with data feeds for dynamic content updates. Their ability to enhance clarity, provide context, and brand video content makes them indispensable in contemporary media production.