| A thru H |
Definition of Terms 
|
| Aliasing |
Incorrect sampled data obtained by either not sampling fast enough
or not bandlimiting the signal prior to sampling. Can result in artifacts
inserted into the image. |
| Artifact |
Any strange or undesired feature of a rendered image. |
| ATV |
Advanced television (high-definition television). |
| Bit rate |
The rate at which a storage medium delivers a compressed bitstream
to a decoder's input. |
| Chrominance |
Portion of a video signal carrying color information. |
| Composite video |
All components (brightness, color, synchronization, etc.) combined
into one signal. See component video. |
| Compression ratio |
The size of the original image divided by the size of the compressed
image, measuring the degree to which a compression routine can reduce the
size of a file. |
| Component video |
The video signal separated into different pieces. See RGB,
S-Video. |
| DBS |
Direct-broadcast satellite (TV). |
| DTV |
Digital television. |
| Field |
The set of alternating lines in an interlaced video frame. An
interlaced frame consists of two fields -- a top field and a bottom field.
A field is one-half of a complete television scanning cycle (1/60 of a
second in NTSC; 1/50 of a second in PAL/SECAM). When interlaced, two fields
combine to make one video frame. |
| Frame |
A single, complete picture in a video or film recording. A video frame
consists of two interlaced fields of either 525 lines (NTSC)
or 625 lines (PAL/SECAM), running at 30 frames per second (NTSC) or 25
fps (PAL/SECAM). Film runs at 24 fps. |
| Frame grabber |
A device which interfaces between a camera and a computer, and captures
a frame of video information sampled into a memory. |
| Frame rate |
The speed at which video frames are scanned or displayed -- 30 frames
a second for NTSC, 25 frames per second for PAL/SECAM. |
HDTV
(High-definition television) |
Any one of a variety of video formats offering greater visual accuracy
(or resolution) than current NTSC, PAL, or SECAM broadcast
standards. HDTV has a bandwidth of 300 MHz. HDTV is subjectively
comparable to 35 mm film. |
| I thru P |
|
| Interframe coding |
In video signal transmission, a way to compress the video signal that
concentrates on coding high-detail areas of a picture at the expense of
the less detailed areas. |
| Interlaced |
The pattern described by two separate field scans when they join to
form a complete video frame. The two field scans interleave together
to form a single, complete frame. |
| Intraframe |
A lossy way to compress a video signal for transmission
in which half the picture information is eliminated by discarding every
other frame as it comes from the camera. During playback, each frame remains
on the screen twice the normal duration to simulate the standard 30-frames-per-second
video rate. |
| ISO |
International Standards Organization |
| JPEG (Joint Photographic Experts Group) |
The international consortium of hardware, software, and publishing
interests who, under the auspices of the ISO, has defined
a universal standard for digital compression and decompression of still
images for use in computer systems (commonly called "JPEG" or "JPEG-Standard")
JPEG compresses at about a 20:1 ratio before visible image degradation
occurs. |
| Lossless compression |
A compression technique that preserves all the original information
in an image or other data structures. |
| Lossy compression |
A compression technique that improves data reduction by discarding
unnecessary image information. |
| MPEG (Motion Picture Experts Group) |
A working committee which has defined standards for the digital compression
and decompression of motion video/audio for use in computer systems.
MPEG-2 is the
currently dominant standard. |
| NTSC format |
A color television format used in the United States. See
also PAL, SECAM. |
| PAL format |
Phase Alternation Line - the European color television format.
See NTSC, SECAM. |
| PDP |
Plasma display panel. |
| Pixel |
An abbreviation of picture element. One way to measure picture
resolution is by the number of pixels used to create images. |
| Q thru Z |
|
| Quantize |
A step in the process of converting an analog signal into a digital
signal. Quantization measures a sample to determine a representative numerical
value that is then encoded. The three steps in analog-to-digital conversion
are sampling, quantizing, and encoding. |
| Real-time |
The actual time in which a program or event takes place. In computing,
real time refers to an operating mode under which data is received and
processed and the results returned so quickly that the process appears
instantaneous to the user. The term is also used to describe the process
of simultaneous digitization and compression of audio and video information. |
| Resolution |
Number of pixels per unit of area. A display with a finer grid contains
more pixels and thus has a higher resolution, capable of reproducing more
detail in an image |
| RGB |
A type of color display output signal comprised of separately controllable
red, green, and blue signals; as opposed to composite video, in which signals
are combined prior to output. RGB monitors typically offer higher resolution
than composite monitors. |
| Scan lines |
The parallel lines across a video screen, along which the scanning
spot travels in painting the video information that makes up a monitor
picture. NTSC systems use 525 scan lines to a screen;
PAL systems use 625. |
| SECAM format |
SEquential Couleur A Memoire (sequential color with memory), the French
color TV system also adopted in Russia. See also NTSC,
PAL. |
| SIF (Standard Interchange format) |
Format for exchanging video images of 240 lines with 352 pixels each
for NTSC, and 288 lines by 352 pixels for PAL
and SECAM. At the nominal field rates of 60 and
50 fields/sec, the two formats have the same data rate |
| S-VHS or Super VHS |
A higher-quality extension of the VHS home videotape format, featuring
higher luminance and the ability to produce better copies. |
| S-video |
Type of video signal used in the Hi8 and S-VHS
videotape formats. S-video transmits luminance and color portions separately,
using multiple wires, thus avoiding the NTSC encoding
process and its inevitable loss of picture quality. Also known as Y/C video. |
| Spatial resolution |
The number of points per unit length into which an image is divided.
For example, 200 dots per inch (dpi). |
| YCbCr |
The three components of component video -- with Y for luma and Cb and
Cr for different chroma components. |
| YUV color system |
A color-encoding scheme for natural pictures in which the luminance
and chrominance are separate. The human eye is less sensitive to color
variations than to intensity variations, so YUV allows the encoding of
luminance (Y) information at full bandwidth and chrominance (UV) information
at half bandwidth. |
Video
Capture/Editing Market Overview