Glossary of Video Terms and Acronyms - Isotest

Video Terms and Acronyms
Glossary
Charge Coupled Device (CCD) – a) A semiconductor device that converts
optical images to electronic signals. CCDs are the most commonly
found type of image sensor in consumer camcorders and video cameras.
b) Serial storage technology that uses MOS capacitors. c) A solid-state
image sensor that converts light energy to electricity.
C-HDTV (Cable HDTV) – A seemingly impossible concept calling for channel-compatible
ATV transmission of 850 lines of both static and dynamic
horizontal and vertical resolution, among other characteristics. Its feasibility
is being studied at ATRP.
Check Box – Used to select from a list of related items. An “x” marks the
selected options in the corresponding box. (Select as many items as
desired – one, none, or all.)
Checkerboard – Automatic assembly process where all edits from mounted
reels are made, and edits for unmounted reels are skipped. Example:
Reels 5, 29, and 44 are mounted on VTRs. The editing system looks at the
list and assembles all edits that have reel numbers 5, 29, and 44 assigned
to them, inserting these events at the exact spot on the master tape where
they belong.
Checksum – a) An error-detecting scheme which is the sum of the data
values transmitted. The receiver computes the sum of the received data
values and compares it to the transmitted sum. If they are equal, the transmission
was error-free. b) Method used to verify the integrity of data
loaded into the computer. c) A simple check value of a block of data, calculated
by adding all the bytes in a block. It is easily fooled by typical
errors in data transmission systems, so that for most applications, a more
sophisticated system such as CRC is preferred.
Chip – Common name for all ICs.
Chip Chart – A black and white test chart. It contains “chips” in varying
intensities, that make up a gray scale. It is used to check the gray scale
taking characteristics of a camera, including the parameter of gamma.
Chip Enable (CE) – See Chip Select.
Chip Select (CS) – Usually enables three-state drivers on the chip’s output
lines. Most LSI chips have one or more chip selects. The CS line is
used to select one chip among many.
Choose – Choose means make a choice to select an action that will take
place, i.e., press the left mouse button to bring up a pop-up menu, move
the cursor to highlight the command that you want to run, then release the
button.
Chroma – a) The depth or saturation of color. The saturation control
adjusts the amplitude of color of the switcher’s matte and background outputs.
b) The (M) NTSC or (B, D, G, H, I) PAL video signal contains two
pieces that make up what you see on the screen: the black and white
(luma) part, and the color part. Chroma is the color part. Chroma can be
further broken down into two properties of color: hue and saturation.
Chroma can also be described as a matrix, block, or single pel representing
one of the two color difference signals related to the primary colors in
the manner defined in the bit stream. The symbols used for the color difference
signals are Cr and Cb.
Chroma Bandpass – In an (M) NTSC or (B, D, G, H, I) PAL video signal,
the luma (black and white) and the chroma (color) information are com-
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bined together. To decode an NTSC or PAL video signal, the luma and chroma
must be separated. The chroma bandpass filter removes the luma from
the video signal, leaving the chroma relatively intact. This works fairly well
except in certain images where the luma information and chroma information
overlap, meaning chroma and luminance information occupy the same
frequency space. Depending on the filtering technique used, it can be difficult
for the filter to separate the chroma from the luminance information.
This results in some luminance information being interpreted as chroma
and some chroma information being interpreted as luminance. The effects
of this improper separation of luminance and chroma are especially noticeable
when the television scene contains objects with thin, closely spaced
black and white lines. As the camera moves across this object, a rainbow
of colors will appear in the object indicating the improper separation of the
luminance and chroma information.
Chroma Burst – See Color Burst.
Chroma Comp – A deliberate distortion of colors usually used to achieve
unusual matching. By detecting the quadrant the color is in (by normally
deciding whether R-Y and B-Y are positive or negative), the amplitude of R-
Y, B-Y just for colors in that quadrant can be changed; hence, the hue and
saturation can be changed for those colors without affecting others.
Chroma Corrector – A device used to correct problems related to the
chroma of the video signal, as well as color balance and color noise.
Chroma Crawl – An NTSC artifact also sometimes referred to as moving
dots; a crawling of the edges of saturated colors in an NTSC picture.
Chroma Crawl is a form of cross-luminance, a result of a television set
decoding color information as high-detail luminance information (dots).
Most ATV schemes seek to eliminate or reduce chroma crawl, possibly
because it is so immediately apparent.
Chroma Demodulation – The process of removing the color video information
from a composite video signal where chrominance information is
modulated on a color subcarrier. The phase reference of the subcarrier, is
color burst which is a phase-coherent sample of the color subcarrier.
Chroma Demodulator – Refer to the NTSC Composite Receiver Model at
the end of this glossary when studying this definition. After the (M) NTSC or
(B, D, G, H, I) PAL video signal makes its way through the Y/C separator, by
either the chroma bandpass, chroma trap, or comb filter method, the colors
are then decoded by the chroma demodulator. Using the recovered color
subcarrier, the chroma demodulators take the chroma output of the Y/C
separator and recovers two color difference signals (typically I and Q or U
and V).
Chroma Flutter – A rapid coherent variation in the chroma saturation.
Chroma Format – Defines the number of chrominance blocks in a macroblock.
Chroma Key (CK) – a) A method of combining two video images. The
most common example of chroma keying is the news weather person
standing in front of a weather map. The details of the process are, a camera
is pointed at the weather person who is standing in front of a bright
blue or green background. The weather person and bright-blue or green
background image is fed into a computing device along with the image of
the weather map. Wherever the computing device sees the bright-blue or
green background, it displays the weather map. Wherever the computing