| Word |
Definition |
| Acquisition |
The manner in which outside information is brought into an analysis system; as an image acquisition - Generally involves A/D conversion. |
| A/D |
Acronym for analog to digital converter; electronic device that converts data from analog form to digital representation. |
| Adaptive Threshold |
A control method in which a threshold is adjusted based on scene content. |
| Algorithm |
A set of well-defined rules or procedures for solving a problem in a finite number of steps, or providing an output from a specific set of inputs. Usually implemented as a computer program. |
| Ambient Light |
Illumination present in the environment possibly surrounding a machine vision system but not supplied by the system. |
| Angle of Incidence |
The angle between the axis of an impinging light beam and the axis perpendicular to the sample surface. |
| Angle of View |
1) The angle formed between two lines drawn from the most widely separated points in the object plane to the center of the lens. 2) The angle between the axis of observation and perpendicular to the specimen surface. |
| Aperture |
An opening to pass light. The effective diameter of the lens controlling the amount of light reaching the image plane. |
| ASCII |
Acronym of American Standard Code for Information Interchange. An 8 bit coded character set used to represent alphanumeric, punctuation marks and certain special control characters. |
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| Back Lighting |
A condition where the light reaching the image sensor is not reflecting from the surface of the object, but is provided behind the objects or area of interest. Back lighting produces a silhouette of the workpiece. |
| Band-Elimination Filter |
A filter that suppresses a given range of frequencies, transmitting only those above and below that band. |
| Bandpass |
The specific range of frequencies or wavelengths, passing through a device. Typically measured between points equal to 50% of maximum amplitude. |
| Barrel Distortions |
An image appearing to bulge outward on all sides like a barrel. Caused by a decrease in effective magnification as points in the image move away from the image center. |
| Beamsplitter |
A device for dividing a light beam into two or more separate beams. |
| Bimodal |
Histogram distribution of values with two peaks.
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| Binary System |
A vision system which creates digitized image of an object in which each pixel can have one of only two values, such as black/white, or zero/one. |
| Blob |
A connected region in a image in which all pixels have the same gray-level value. |
| Blooming |
The smearing of regions of the image where the detected brightness is at an excessive level to the receiving element due to electronic contamination from neighboring bright pixels. |
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| C-Mount |
Threaded lens mount developed from 16 mm movie work; used extensively from closed-circuit television. The threads have a major diameter of 1 inches and a pitch of 32 threads per inch. The flange focal distance is .69 inches. |
| Calibration |
Determination of the relationship between the output of a measuring instrument and some fiducial mark, accepted standard of measurement, or other reference datum for the purpose of reporting future results relative to the reference. |
| Centroid |
The object of measurement; in the case of a two-dimensional binary image object the average X and Y pixel coordinate. |
| Collimated |
A beam of light in which all optical rays are parallel. |
| Contrast |
The r.ange of difference between light and dark values in an image. Usually expressed as a Contrast Ratio |
| Correlation |
A process whereby two image segments are compared to determine their similarity, or to find the position at which optimal similarity exists. The two images are called the window and the Template or Golden Image. Applications of correlation include target tracking, defect detection, and stereo correspondence. |
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| Dark Field |
An illumination technique supplying the illumination at a shallow (grazing) angle to the surface of the workpiece. Ordinarily only a negligible amount of light reflects into the camera. Specular reflections occur off any abrupt surface irregularities, and are detectable in the image. |
| Depth-of-field |
The in-focus range of an imaging system. Measured from the distance behind an object to the distance in front of the object with all objects appearing in focus. |
| Depth-of-focus |
The range of lens to image plane distance having the image formed by the lens appearing in focus. |
| Diffuse |
The process of redirecting incident light over a range of angles (scattered) while reflecting from or transmitting through a material. |
| Distortion |
An undesired change in the shape of an image or waveform from the original object or signal. |
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| Edge |
A change in pixel values exceeding some threshold between two adjacent regions of relatively uniform values. Edges correspond to changes in brightness corresponding to a discontinuity in surface orientation, reflectance, or illumination. |
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| Feature |
Any characteristic descriptive of an image or a region in an image. |
| Feature Extraction |
The process of generating a set of descriptors or characteristic attributes from a binary image. |
| Fiducial Mark |
A mark defining a datum point or standard of positional reference used as a basis for calculation or measurement. |
| Field of View |
The area of object space imaged at the focal plane of a camera. |
| Fluorescent Lamp |
A lamp producing light by exciting a phosphor with a plasma with the phosphor re-emitting the energy as light. |
| f/Number |
Ratio of the focal length of a system to the diameter of the entrance pupil. |
| Focal Length |
The distance from a lens' principal point to the corresponding focal point. Also referred to as the equivalent focal length and the effective focal length. |
| Frame |
A total area, occupied by a television image, scanned during video signal unblanking. Two fields, an odd and even, make one frame. |
| Frame Grabber |
A device interfaced with a camera storing in memory, on command, sampled video converted to digital signals. |
| Front Lighting |
An arrangement in which the object is illuminated and viewed from the same side. |
| f/stop |
The ratio of the focal length of a system to the diameter of the entrance pupil. |
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| Gradient Magnitude |
The rate-of-change of pixel intensities over a small local neighborhood. |
| Gray Scale |
Variations of values from white, through shades of gray, to black in a digitized image with black assigned the value of zero and white the value of one. |
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| Halogen |
A gas such as iodine placed inside an incandescent lamp to gather the evaporated filament off the bulb and redeposit it back onto the filament. |
| High Pass Filter |
A gray scale processing operation that enhances high frequencies (and attenuates low frequencies.) |
| Histogram |
Frequency counts of the population of pixels of each intensity (gray level) or other characteristic populations in an image. |
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| Incandescent |
Thermal generation of light, usually through radiant filaments in a bulb. |
| Incident Light |
The light falling directly on an object. |
| Inverse Square Law |
The decrease of light intensity with increasing distance raised to the square power. |
| Iris |
An adjustable aperture built into a camera lens to permit control of the amount of light passing through the lens. |
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| LED |
Acronym for Light-Emitting Diode |
| Line Scan |
One dimensional image sensor. A linear array of photo detectors. |
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| Mask |
A pattern used to control the retention or elimination of portions of another pattern. Regions of an image at a constant value, usually white or black, form the mask. |
| Masking |
An operation setting regions of an image to a constant value, such as white or black. |
| Model based recognition |
Recognizing an object based on a geometrical description of its edge relationships. |
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| Neural Network |
A processing architecture derived from models of neuron interconnections of the brain. Typically different from computers by incorporating learning rather than programming and parallel rather than sequential processing. |
| Noise |
Irrelevant or meaningless data resulting from various caused unrelated to the source of data being measured or inspected; random undesirable video signals. |
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| OCR |
Acronym for Optical Character Recognition. Recognition of each character in a string by a vision system. |
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| Parallax |
The difference in appearance or position of an object when viewed from two different locations. |
| Parallel-Pipeline |
Machine vision system design tin which the image enters a sequential pipeline of processors in which many different operators are applied to the image simultaneously. |
| Photon |
A particle of light. A quantum of electromagnetic energy moving at the speed of light. |
| Pin-Cushion Distortion |
An effect making the sides of an image appear to bulge inward on all sides like a pin-cushion. Caused by an increase in effective magnification as points in the image move away from the image center. |
| Pixel |
Acronym for picture element. |
| Polarization |
The restriction of the vibrations of light or magnetic field vectors to one plane. |
| Polarized Lighting |
The used of polarizing filters to remove Specular reflection from a scene to be viewed. Typically, one polarizing filter is placed in front of the light source and a second filter is place over the receiver at 90 degrees. |
| Preprocessing |
Enhancement, transformation, or filtering of images before processing. |
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| Recognition |
A match between a description derived from an image and a description obtained from a stored model or feature set. |
| Region of Interest (ROI) |
The area inside defined boundaries that the user wants to analyze. |
| Repeatability |
The degree to which repeated measurements of the same quantity vary about their mean. |
| Resolution |
1) The smallest detectable change in position or size of an object. 2) The closest distance between two objects (points) in an image identifiable as two separate objects rather than one object. |
| RS-170 |
Electronic Industries Association (EIA) standard governing monochrome television studio electrical signals. Specifies maximum amplitude of 1.4v, peak to peak, including synchronization pulses. |
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| Shift Register |
An electronic circuit consisting of a series of storage locations (registers). During each clock cycle the information in each location moves (shifted) into the adjacent location. |
| Signal-to-noise-ratio |
The ratio of the maximum value of an output signal to the standard deviation amplitude of the noise on the signal. |
| Snap |
Term frequently used in machine vision to indicated the loading of a camera image into a buffer. |
| Strobe Light |
A pulsed illumination source which uses lamp generating a short burst of high intensity light. |
| Sub-Pixel Resolution |
Any technique resulting in a measurement with a resolution (interpolated position of change) less than one pixel. |
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| Template Matching |
Comparing a template with an object in an image. Usually performed at the pixel level as with a template correlation. |
| Threshold |
Intensity (specific pixel value) below which a stimulus produces no effect or response. Often used to convert a gray scale or analog image into a binary image. |
| Thresholding |
Scene segmentation process based on converting a gray-scale image into a binary image by reassigning pixel gray levels to only two values. Regions of the binary image are separated based on whether pixel values in the gray scale image were above or below a chosen intensity level. |
| Throughput |
The total capability of equipment to process or transmit data during a specified time period. |
| Tolerance |
Amount that establishes the range upon which to base the differentiation between good and bad products. |
| Translation |
Movement left or right, up or down, but not rotated; geometrical operation which shifts the position of an image from its original position. |
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| Zoom |
Electronically or optically enlarging or reducing the size of an image. |
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