| AccuSentry | |
| ADC | ADC = analog digital converter An analog-to-digital converter
(abbreviated ADC, A/D, or A to D) is a device that converts continuous
signals to discrete digital numbers. Typically, an ADC converts a
voltage to a digital number. A digital-toanalog converter (DAC) performs
the reverse operation. |
| AEC | AEC = auto exposure control
|
AFE
| AFE = analog front end The AFE
conditions the analog signal received from the image sensor and performs
the analog-to-digital (A/D) conversion. |
| AGC | AGC = auto gain control AGC means
that the electronic amplification of the video signal is automatically
adjusted to compensate for varying levels of scene illumination. |
| AGP |
Accelerated
Graphics Port (AGP) is an interface specification that enables 3D
graphics to display quickly on ordinary personal computers. |
| Aliasing | Phenomenon of interference which
occurs when a signal being sampled contains frequencies that are higher
than half the sampling frequency. Typically can be seen as ragged edges
on horizontal lines. |
| Analog | A type of signal in an electronic circuit that takes on a continuous range of values. The opposite of digital. |
| Analog front end | See AFE; AFE = analog front end. The
AFE conditions the analog signal received from the image sensor and
performs the analog-to-digital (A/D) conversion. |
| Angstrom | Unit of length. One angstrom = 1 Å = 10-10 meters = 0.0000000001 meters
= 0.1 nanometers. Angstroms are the units generally used when
discussing wavelengths of light. |
| Ant-Blooming | Some sensors, offer an optional anti-blooming gate designed to bleed off
overflow from a saturated pixel. Without this feature, a bright star
which has saturated the pixels (much greater than 85,000 electrons) will
cause a vertical streak. This can be irritating at best, and if the
streak bleeds onto your target object, there is no way to recover the
lost data. CCDs with Anti-blooming gate protection are NOT recommended
for low light level work because of the reduced sensitivity of these
devices IF a better option is available. Because of these drawbacks,
users of CCDs without anti-blooming gates have chosen an alternate
method to avoid blooming. Rather than taking a single long exposure in
which blooming is almost certain to occur, take several short exposures,
in which the brightest objects haven't begun to bloom, and stack the
exposures together with image processing software. The signal-to-noise
ratio remains the same as in the longer exposure, but the result is free
of anti-blooming.
Anti-blooming gates built into the CCD occupy about 30% of the
pixel area. The result is a 70% fill factor and reduced sensitivity and
well depth. The reduced sensitivity means that you have to expose almost
twice as long to get the same signal level as a CCD without the
anti-blooming feature. Also, the area of the CCD occupied by the
anti-blooming gate leaves a significant gap between pixels, reducing the
effective resolution of the sensor. Most of the CCDs we sell, such as
the Kodak KAF-1001e, KAF-4200, E2V 47-10 and 42-40 do not have
anti-blooming gates. All of our Interline CCDs such as the kai-2020 and
4020 do have anti-blooming gates.
Since opinions vary on which is the ideal method to achieve anti-blooming, we offer the following guidelines for selection:
1. If non-blooming of bright objects is critical for your
application, and if guiding twice as long to overcome the loss in
sensitivity is not bothersome, then the anti-blooming option may be for
you.
2. For tri-color imaging, front-illuminated CCDs already
have low response in the blue. Therefore, the lessened response with the
anti-blooming gates will require extremely long exposures with the blue
filter to obtain good color balance. For this and other applications
that require good response to blue light, you may wish to use the
stacking method to avoid blooming. |
| AOI | AOI = area of interest; see "Area Of Interest" |
| Application Specific Machine Vision System | A turnkey machine vision
system that addresses a specific application found throughout one or
more industries |
Area Lighting
| Lighting used for the illumination of an area |
| Area Camera | All cameras covering an area at once rather than a single line at a
time. Area Cameras are of two types: interlaced and progressive scan. |
| Area Of Interest | Area of interest readout (AOI) refers
to a camera function whereby only a portion of the available pixels are
read out from the camera. For example, it is possible to read out a 10 x
20 pixel rectangular area of pixels from a camera that has a total
resolution of 648 x 488. The result is a much faster frame rate and less
data to be processed. This is also referred to as partial scan. Various
autofunctions (auto shutter, auto gain, auto white balance) act on the
AOI. |
| Asynchronous Shutter | The camera CCD starts to accumulate electrons on receipt of an external trigger pulse. |
| Asynchronous Transmission Mode | Asynchronous transmission mode is a mode supported by IEEE 1394 includes
receipt datagrams that indicate that the data was transmitted includes
receipt datagrams that indicate that the data was transmitted reliably
to the 1394 device. Asynchronous data transfers place emphasis on
delivery rather than timing. The data transmission is guaranteed, and
retries are supported. An example for an asynchronous transmission mode
is the one-shot comand. All cameras receive the one-shot command in the
same IEEE 1394 bus cycle. This creates uncertainty for all cameras in
the range of 125 µs. |
| Auto Median | Dual combinations of openings and closings. Auto Median generates simpler objects with fewer details. |
| Auto Threshold: Clustering | Applies a threshold to an image based on a statistical technique called clustering. |
| Auto Threshold: Entropy | Applies a threshold to an image based on an image analysis technique called entropy. |
| Auto Threshold: Inter Variance | Applies a threshold to an image based on a classical statistical technique called interclass variance. |
| Auto Threshold: Metric | Applies a threshold to an image by
calculating the optimal threshold, which depends on the surfaces
representing the initial grayscale, using the metric technique. |
| Auto Threshold: Moments | Applies a threshold to an image by using a statistical tool called moments, which recalculates a theoretical binary image. |
| AWB | AWB = auto white balance; A system for automatically setting the white balance in digital cameras. See white balance |
