Glossary And Formulas Flashcards
10-bit
A video system where each colour has 1024 possible levels (0-1023).
4:4:4
Highest quality sampling for high-end transcoding, particularly for feature film. Used extensively for visual effects work. For every 4 samples of Y, there are 4 samples of CR and 4 samples of CB.
4K
An emerging set of digital video standards where the horizontal width of a picture is around 4000 pixels.
8-bit
A video system where each colour channel has 256 possible levels (0-255)
Active video
Lines in an analogue video system used for picture.
Aliasing
An artefact where insufficient chrominance information to show clean transitions between areas of significant colour difference, causes stair-stepping, noticeable on curved or diagonal edges of objects in frame.
Alpha channel
A fourth channel stored in some file formats e.g. TIFF. Not usually captured by cameras. Commonly used for encoding transparency for compositing.
Anti-aliasing
A technique used to reduce visible aliasing.
Aperture (iris)
The opening in the lens that lets light fall on the imager. Measured in f-stops or T-stops. large aperture causes shallow depth of field.
Artefacts
Unwanted features in an image, often caused by sampling or compression.
Baby mount
Receptacle for 5/8” pin from stand for a lighting fixture.
Back porch
The part of an analogue video signal prior to the active video that contains colour burst information.
Bail
Mounting point for a lighting fixture where the housing attaches to the stand.
Banding
A sampling artefact: bands of colour become visible when the bit depth does not allow enough colours to accurately show a gradient of colour.
Barn doors
Hinged flaps on a lighting fixture that allow general control of beam.
Bayer filter
A filter used in digital imagers to derive colour information. Each area of a bayer filter allows only red, green or blue light to hit the photosite beneath it.
Bit depth
Refers to the level of data in a given sample. A bit depth of 8 has 256 levels per channel (0-255).
Bit
The smallest unit of information in a digital system. A bit can have only one of two values: on or off, usually referred to as 1 or 0.
Bounce board
A polystyrene or foam core sheet held by a stand to enable a soft light source to be created from a hard source.
Brightness adaptation
Perception of the brightness of a colour can be affected by surrounding colours.
Caboose effect
An approach to film production where the final distribution format is used to make logistical decisions (named for the caboose:in the USA, this is the final car on a railway train).
Candela
A measurement of intensity from a light source (cd).
CCD (charged coupling device)
Longstanding analogue system to record video: light hits a photo-site, a chip chip converts it to a voltage. The camera converts voltage into digital picture information.
Circle of confusion:
CoC: a measure of resolving power used in Depth of Field calculations. The largest blur spot that will still be perceived by the human eye as a point.