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Quadrus MINI Imager User’s Manual
A-31
Appendices
Appendix K — Glossary of Terms
Aberration — The failure of an optical lens to produce an exact point-to-point correspondence
between the object and its resulting image. Various types are chromatic, spherical, coma,
astigmatism and distortion.
Absorption — The loss of light of certain wavelengths as it passes through a material and
is converted to heat or other forms of energy. (–)
Active Illumination — Lighting an area with a light source coordinated with the acquisition
of an image. Strobed flash tubes and pulsed lasers are examples.
ADC — See Analog-to-Digital Converter.
A/D Converter — See Analog-to-Digital Converter.
AGC — See Automatic Gain Control.
Ambient Light — Light which is present in the environment of the imaging front end of a
vision system and generated from outside sources. This light, unless used for actual illumination,
will be treated as background Noise by the vision system.
Analog — A smooth, continuous voltage or current signal or function whose magnitude
(value) is the information.
Analog-to-Digital Converter (A/D Converter or ADC) — A device that converts an
analog voltage or current signal to a discrete series of digitally encoded numbers (signal)
for computer processing.
Application-Specific Integrated Circuit (ASIC) — An integrated circuit that is customized
for a particular kind of use, rather than general use. All vision system elements including
firmware can be integrated into one ASIC.
Architecture — The hardware organization of a vision system designed for high speed
image analysis.
ASIC — See Application-Specific Integrated Circuit.
Aspect Ratio — The ratio between the height and width of a sensor or display. Found by
dividing the vertical number of pixels (height) by the horizontal number of pixels (width)
leaving it in fractional format.
Automatic Gain Control (AGC) — Adjustment to signal strength that seeks to maintain a
constant level regardless of the distance between a reader and symbol.
Auxiliary Port — RS-232 connection to an auxiliary terminal or device for remote viewing.
Blooming — A situation in which too many photons are being produced to be received by
a pixel. The pixel overflows and causes the photons to go to adjacent pixels. Blooming is
similar to overexposure in film photography, except that in digital imaging, the result is a
number of vertical and/or horizontal streaks appearing from the light source in the picture.
Baud Rate — The number of discrete signal events per second; bits per second.
Capture — The act of acquiring and storing video images in an imager or host computer.
Also, the image captured.
CCD — See Charge-Coupled Device.