HD Player
Index
108
Rev. 6.4
Color space
The color range between specified references. Typically references are quoted in
television: RGB, Y, R-Y, B-Y, YIQ, YUV and Hue Saturation and Luminance
(HSL). In print, Cyan, Magenta, Yellow and Black (CMYK) are used. Moving
pictures between these is possible but requires careful attention to the accuracy
of processing involved. Operating across the media-print, film and TV, as well
as between computers and TV equipment-will require conversions in color
space.
Color space
conversion:
The translation of color value from one color space to another. Since different
media types, like video and computer graphics, use different color spaces, color
space is often performed on the fly by graphics hardware.
Composite
(video)
Luminance and chrominance are combined along with the timing reference
"sync" information using one of the coding standards-NTSC, PAL or SECAM-to
make composite video. The process, which is an analog form of video
compression, restricts the bandwidths (image detail) of components. In the
composite result color is literally added to the monochrome (luminance)
information using a visually acceptable technique. As our eyes have far more
luminance than color resolving power, the color sharpness (bandwidth) of the
coded signal is reduced to far below that of the luminance. This provides a good
solution for transmission but it becomes difficult, if not impossible, to accurately
reverse the process (decode) into pure luminance and chrominance which limits
its use in post-production.
Compression:
Reduction of the size of digital data files by removing redundant information
(Lossless) or removing non-critical data (Lossy).
Pictures are analyzed looking for redundancy and repetition and so discard
unnecessary data. The techniques were primarily developed for digital
transmission but have been adopted as a means of handling digital video in
computers and reducing the storage demands for digital VTRs. Compression can
be at either a set rate or a variable rate.
Also known as Bit Rate Reduction (BRR)
Compression
artifacts:
Compacting of a digital signal, particularly when a high compression ratio is
used, may result in small errors when the signal is decompressed. These errors
are known as "artifacts," or unwanted defects. The artifacts may resemble noise
(or edge "busyness") or may cause parts of the picture, particularly fast moving
portions, to be displayed with the movement distorted or missing.
Contouring
Digital video picture defect caused quantizing at too coarse a level.
DCT
1. Discrete cosine transform. A widely used method of data compression of
digital video pictures basically by resolving blocks of the picture (usually 8 x 8
pixels) into frequencies, amplitudes, and colors. JPEG and DV depend on DCT.
2. Also an Ampex data videotape format using discrete cosine transform.
Demultiplexing
Separating elementary streams or individual channels of data from a single
multi-channel stream. For example, video and audio streams must be
demultiplexed before they are decoded. This is true for multiplexed digital
television transmissions.
See also: Multiplex.
Dolby Digital
(formerly Dolby
AC-3):
The approved 5.1 channel (surround-sound) audio standard for ATSC digital
television, using approximately 13:1 compression
EBU
European Broadcasting Union. An organization of European broadcasters that,
among other activities, produces technical statements and recommendations for
the 625/50 line television system. CP 67, CH-1218 Grand-Saconnex GE,
