Category Archives: K

Keycode

A machine-readable barcode printed along the edge of camera negative film stock outside the perforations. It gives key numbers, film type, film stock manufacturer code, and offset from zero-frame reference mark (in perforations). It has applications in telecine and film scanning for accurate film-to-tape or data transfer and in editing for conforming neg. cuts to EDLs.

Keyframe

A set of parameters defining a point in a transition, e.g. of a DVE effect. For example a keyframe may define a picture size, position and rotation. Any digital effect must have a minimum of two keyframes, start and finish, although complex moves will use more, maybe hundreds.

Increasingly, more parameters are becoming ‘keyframeable’, i.e. they can be programmed to transition between two, or more, states. Examples are color correction to make a steady change of color, and keyer settings, perhaps to make an object slowly appear or disappear.

See also: DVE

Keying

The process of selectively overlaying an area of one picture (or clip) onto another. If the switch between the overlaid and background pictures is simply ‘hard’ this can lead to jagged edges of the overlaid, or keyed, pictures. They are usually subjected to further processing to produce ramped, slightly soft, key edges to give a cleaner, more convincing, result. The whole technology of deriving key signals from image data and the color corrections applied to keyed image edges, has greatly expanded through the use of digital technology, so that many operations may be used together, e.g. softening the key, color correcting key spill areas, and much more.

See also: Chroma keying, Digital keying, Linear keying

Keystoning (Stereoscopic)

This can occur when the two cameras are ‘toed-in’ so that the object of interest coincides when viewed. There can be some mismatching of the outlines or borders of the two images. Techniques like corner pinning can be used to help correct this.

KLV

KLV is a data encoding protocol (SMPTE 336M). The Key is a unique, registered sequence of bits that defines the type of content that is coming (video, audio, EDL, etc) and Length – number of bytes ahead of Value, the content ‘payload’ itself. Compliance to KLV means that a wider range of equipment and applications can understand each others’ files.

See also: AAF, MXF