| 1D | One-dimensional. |
| 2D | Two-dimensional. |
| 3D | Three-dimensional. |
A |
| acceptance level | Value that indicates how closely an object
must match a trained character to be recognized. A high acceptance level value indicates
that the object and trained character must be closely matched for the object
to be recognized. (OCR) |
| alpha channel | Channel used to code extra information, such as Gamma correction, about an image. |
| area threshold | Detects objects based on their size. |
| arithmetic operators | The image operations multiply, divide, add, subtract, and remainder. |
| artifacts | Extraneous pixels in the region of interest. (OCR) |
| aspect ratio | Height/width ratio of a character. (OCR) |
| auto-median function | A function that uses dual combinations of opening and closing operations to smooth the boundaries of objects. |
| AutoSplit | Works in conjunction with the maximum character bounding rectangle width, and
uses an algorithm to analyze the right side of a character bounding rectangle. AutoSplit then determines
the rightmost vertical line in the object that contains the fewest number of pixels and moves the
rightmost edge of the character bounding box to that location. (OCR) |
B |
| barycenter | The value representing the centroid of the range of an image’s grayscale values in the image histogram. |
| binary image | An image containing objects usually represented with a pixel intensity of 1 (or 255) and the background of 0. |
| binary morphology | Functions that perform morphological operations on a binary image. |
| BMP | Bitmap. Image file format commonly used for 8-bit and color images (extension .bmp). |
| border function | Removes objects (or particles) in a binary image that touch the image border. |
C |
| caliper | A function that calculates distances, angles, circular fits, and the center of mass based on positions given by edge detection, particle analysis, centroid, and search functions. |
| CCD | Charge-coupled device. A solid-state imaging device that stores an electrical charge representation of the optical image by means of photoconductivity. A readout mechanism converts the charge image into a video signal. |
| center of mass | The point on an object where all the mass of the object could be concentrated without changing the first moment of the object about any axis. |
| centroid |
- The average of the x-coordinates and y-coordinates of a binary image or a particle in the image. The centroid of a particle may lie outside the particle.
- The weighted average of the x-coordinates and y-coordinates in a grayscale image, where the weights are determined by the pixel values in the image.
|
| character | Recognized group of foreground elements. (OCR) |
| character bounding rectangle | Smallest rectangle that completely encloses a character. (OCR) |
| character recognition | Ability of a machine to read human-readable text. (OCR) |
| character segmentation | Application of several parameters, such as thresholding,
character size, and element spacing, that isolates a character in a region of interest. (OCR) |
| character set | Set of trained characters and/or patterns. (OCR) |
| character set file | File that contains a character set. (OCR) |
| character size | Number of pixels that make up a character. (OCR) |
| character spacing | Horizontal distance between the right edge of one character bounding rectangle and the left edge of the next character bounding rectangle. (OCR) |
| character value | String that describes a character. For example, you might assign the character value "A" to a group of elements that resembles the letter A. (OCR) |
| circle function | Detects circular objects in a binary image. |
| classification | An operation that assigns samples to classes based on predefined features. |
| closing | A dilation followed by an erosion. A closing fills small holes in objects and smooths the boundaries of objects. |
| clustering | Technique where the image is sorted within a discrete number of classes corresponding to the number of phases perceived in an image. The gray values are determined and a barycenter is determined for each class. This process is repeated until a value is obtained that represents the center of mass for each phase or class. |
| codeword | Numeric value of the printed bar/space pattern in a 1D or 2D barcode. |
| color images | Images containing color information, usually encoded in the RGB form. |
| color look-up table (CLUT) | Table for converting the value of a pixel in an image into a red, green, and
blue (RGB) intensity. |
| connectivity | Defines which of the surrounding pixels of a given pixel constitute its neighborhood. See also connectivity-4 and connectivity-8. |
| connectivity-4 | Connectivity where only pixels adjacent in the horizontal and vertical directions are considered neighbors. Two pixels are considered as part of a same object if they are horizontally or vertically adjacent. They are considered as part of two different objects if they are diagonally adjacent. |
| connectivity-8 | Connectivity where all adjacent pixels are considered neighbors. Two pixels are considered as part of a same object if they are horizontally, vertically, or diagonally adjacent. |
| convex function | Computes the convex regions of objects in a binary image. |
| convolution | See linear filter. |
| convolution kernel | Simple 3 × 3, 5 × 5, or 7 × 7 matrices (or templates) used to represent the filter in the filtering process. The contents of these kernels are a discrete two-dimensional representation of the impulse response of the filter that they represent. |
| coordinate system | A reference location (origin) and angle in an image that regions of interest can relate to when positional and angular adjustments of the region of interest are necessary. A coordinate system is depicted by two lines representing the orientation and direction of its two axes. |
D |
| Danielsson function | Similar to the distance functions, but with more accurate results. |
| definition | The number of values a pixel can take on, which is the number of colors or shades that you can see in the image. |
| dendrite | Branches of the skeleton of an object. |
| density function | For each gray level in a linear histogram, it gives the number of pixels in the image that have the same gray level. |
| device | Plug-in data acquisition board that can contain multiple channels and conversion devices. |
| differentiation filter | Extracts the contours (edge detection) in gray level. |
| digital camera | A camera that transforms light information into pixels and then translates each pixel's level of light into a digital number inside the camera. |
| digital image | An image f (x, y) that has been converted into a discrete number of pixels. Both spatial coordinates and brightness are specified. |
| dilation | Increases the size of an object along its boundary and removes tiny holes in the object. |
| distance calibration | Determination of the physical dimensions of a pixel by defining the physical dimensions of a line in the image. |
| distance function | Assigns to each pixel in an object a gray-level value equal to its shortest Euclidean distance from the border of the object. |
| dot-matrix character | Character comprised of a series of small elements. See segmented character. (OCR) |
| driver | Software that controls a specific hardware device, such as a data acquisition board. |
E |
| edge | Defined by a sharp change (transition) in the pixel intensities in an image or along an array of pixels.
|
| element | Connected group of foreground pixels. Adjacent elements form a character. See object. (OCR) |
| element spacing | Amount of space, in pixels, between elements. See horizontal element spacing and vertical element spacing. (OCR) |
| entropy | Method based on a classical image analysis technique that is best suited for detecting objects present in minuscule proportions on the image. For example, this function would be suitable for default detection. |
| equalize function | See histogram equalization. |
| erasure | Missing or undecodable codeword at a known position in a 2D barcode. |
| erosion | Reduces the size of an object along its boundary and eliminates isolated points in the image. |
| error | See substitution error. |
| exponential and gamma corrections | Expand the high gray-level information in an image while suppressing low gray-level information. |
| exponential function | Decreases the brightness and increases the contrast in bright regions of an image, and decreases contrast in dark regions. |
F |
| falling edge | The digital signal transition from the high state to the low state. |
| FFT | Fast Fourier Transform. A method used to compute the Fourier transform of an image. |
| field of view | Area of inspection that the camera can acquire as an image. |
| finder pattern | A specific pattern or sequence used by 2D codes to identify the orientation of data in the 2D code. |
| focal point | The pixel location in a pattern matching template whose coordinates are returned as the location of a match in the inspection image. |
| Fourier spectrum | The magnitude information of the Fourier transform of an image. |
| Fourier transform | Transforms an image from the spatial domain to the frequency domain. |
| frequency filters | Counterparts of spatial filters in the frequency domain. For images, frequency information is in the form of spatial frequency. |
| function | Set of software instructions executed by a single line of code that may have input and/or output parameters and returns a value when executed. |
G |
| Gaussian filter | A filter similar to the smoothing filter, but using a Gaussian kernel in the
filter operation. The blurring in a Gaussian filter is more gentle than a smoothing filter. |
| Gigabit Ethernet | Technologies which transmit Ethernet packets at a rate of one gigabit per second. |
| GigE Vision | A camera interface standard developed using the Gigabit Ethernet communication protocol. |
| grab | Acquisition technique that acquires and displays a continuous sequence of images using an image acquisition. Use this acquisition technique when you need to focus your camera. |
| gradient convolution filter | See gradient filter. |
| gradient filter | Extracts the contours (edge detection) in gray-level values. Gradient filters include the Prewitt and Sobel filters. |
| gray level | The brightness of a pixel in an image. |
| gray-level dilation | Increases the brightness of pixels in an image that are surrounded by other pixels with a higher intensity. |
| gray-level erosion | Reduces the brightness of pixels in an image that are surrounded by other pixels with a lower intensity. |
| grayscale image | An image with monochrome information. |
| grayscale morphology | Functions that perform morphological operations on a grayscale image. |
H |
| highpass attenuation | Applies a linear attenuation to the frequencies in an image, with no attenuation at the highest frequency and full attenuation at the lowest frequency. |
| highpass FFT filter | Removes or attenuates low frequencies present in the FFT domain of an image. |
| highpass filter | Emphasizes the intensity variations in an image, detects edges (or object boundaries), and enhances fine details in an image. |
| highpass frequency filter | Attenuates or removes (truncates) low frequencies present in the frequency domain of the image. A highpass frequency filter suppresses information related to slow variations of light intensities in the spatial image. |
| highpass truncation | Removes all frequency information below a certain frequency. |
| histogram | Indicates the quantitative distribution of the pixels of an image per gray-level value. |
| histogram equalization | Transforms the gray-level values of the pixels of an image to occupy the entire range (0 to 255 in an 8-bit image) of the histogram, increasing the contrast of the image. |
| hole filling function | Fills all holes in objects that are present in a binary image. |
| horizontal element spacing | Space, in pixels, between horizontally adjacent elements. (OCR) |
| HSI | Color encoding scheme in Hue, Saturation, and Intensity. |
| HSL | Color encoding scheme in Hue, Saturation, and Luminance. |
| HSV | Color encoding scheme in Hue, Saturation, and Value. |
I |
| IEEE | Institute of Electrical and Electronics Engineers. |
| IEEE 1394 | IEEE 1394, also known as FireWire®, is a high-performance serial bus originally developed by Apple computer in the early 1990s. The baseline specification handles throughput rates of 100 Mbits/s, 200 Mbits/s, and 400 Mbits/s. IEEE 1394 also features hot pluggable technology that enables devices to be connected and disconnected while your system is powered. |
| image | Light intensity as a function of the spatial coordinates f (x, y) where x and y denote spatial coordinates and the value f at any point (x, y) is the light intensity at that point. |
| image border | A user-defined region of pixels surrounding an image. Functions that process pixels based on the value of pixel neighbors require image borders. |
| image file | A file containing pixel data and additional information about the image. |
| image mask | A binary image that isolates parts of a source image for further processing. A pixel in the source image is processed if its corresponding mask pixel has a non-zero value. A source pixel whose corresponding mask pixel has a value of 0 is left unchanged. |
| image palette | The gradation of colors used to display an image on screen, usually defined by a color look-up table. |
| image processing | Encompasses various processes and analysis functions which you can apply to an image. |
| image source | Original input image. If you start processing an image and want to revert back to the original image, select Source Image from the list box. When you click on Source Image, the image reverts to the original image, and any processing done on the image prior to selecting Image Source is cancelled. |
| image visualization | The presentation (display) of an image (image data) to the user. |
| inner gradient | Finds the inner boundary of objects. |
| inspection | A vision inspection application created in and ran from Vision Builder AI that can perform inline or offline visual inspections. |
| inspection functions | Detects specific features in an image. The features detected include edges, peaks, and rotational shifts. |
| intensity | The gray-level value of a pixel in a grayscale image. |
| intensity threshold | Characterizes an object based on the range of gray-level values in the object. If the intensity range of the object falls within the user specified range, it is considered an object; otherwise it is considered part of the background. |
| interclass variance | Classical statistic technique used in discriminating factorial analysis. This method is best suited for images in which classes are not too disproportionate. For satisfactory results, the smallest class must be at least five percent of the largest one. This method has the tendency to underestimate the class of the smallest standard deviation if the two classes have a significant variation. |
| interpolation | Is the technique used to find values in between known values when resampling an image or array of pixels. |
J |
| JPEG | Joint Photographic Experts Group. Image file format for storing 8-bit and color images with lossy compression (extension .jpg). |
K |
| kernel | Structure that represents a pixel and its relationship to its neighbors. The relationship is specified by weighted coefficients of each neighbor. |
L |
| labeling | The process by which each object in a binary image is assigned a unique value. This process is useful for identifying the number of objects in the image and giving each object a unique identity. |
| LabVIEW | Laboratory Virtual Instrument Engineering Workbench. Program development environment application based on the programming language G used commonly for test and measurement applications. |
| Laplacian filter | Extracts the contours of objects in the image by highlighting the variation of light intensity surrounding a pixel. |
| line profile | Represents the gray-level distribution along a line of pixels in an image. |
| linear filter | A special algorithm that calculates the value of a pixel based on its own pixel value as well as the pixel values of its neighbors. The sum of this calculation is divided by the sum of the elements in the matrix to obtain a new pixel value. |
| logarithmic and inverse gamma corrections | Expand low gray-level information in an image while compressing information from the high gray-level ranges. |
| logarithmic function | Increases the brightness and contrast in dark regions of an image, and decreases the contrast in bright regions of the image. |
| logic operators | The image operations AND, NAND, OR, XOR, NOR, difference, mask, mean, max, and min. |
| look-up table | Table containing values used to transform the gray-level values of an image. For each gray-level value in the image, the corresponding new value is obtained from the look-up table and applied to the image. |
| lossless compression | Compression in which the decompressed image is identical to the original image. |
| lowpass attenuation | Applies a linear attenuation to the frequencies in an image, with no attenuation at the lowest frequency and full attenuation at the highest frequency. |
| lowpass FFT filter | Removes or attenuates high frequencies present in the FFT domain of an image. |
| lowpass filter | Attenuates intensity variations in an image. You can use these filters to smooth an image by eliminating fine details and blurring edges. |
| lowpass frequency filter | Attenuates high frequencies present in the frequency domain of the image. A
lowpass frequency filter suppresses information related to fast variations of light intensities in the spatial image. |
| lowpass truncation | Removes all frequency information above a certain frequency. |
| L-skeleton function | Uses an L-shaped structuring element in the Skeleton function. |
M |
| match score | A number ranging from 0 to 1000 that indicates how closely an area of an acquired image matches the template image. A match score of 1000 indicates a perfect match. A match score of 0 indicates no match. |
| median filter | A lowpass filter that assigns to each pixel the median value of its neighbors. This filter effectively removes isolated pixels without blurring the contours of objects. |
| metric | Technique used in situations similar to interclass variance. For each threshold, a value is calculated that is determined by the surfaces representing the initial grayscale. The optimal threshold corresponds to the smallest value. |
| module |
- A single cell that encodes one bit of data in a Data Matrix barcode.
- The narrowest discernible element in a PDF417 barcode.
|
| moments | Technique best suited for images that have poor contrast (an overexposed image is better processed than an underexposed image). The moments method is based on the hypothesis that the observed image is a blurred version of the theoretically binary original. The blurring that is produced from the acquisition process (electronic noise or slight defocalization) is treated as if the statistical moments (average and variance) were the same for both the blurred image and the original image. This function recalculates a theoretical binary image. |
| morphological transformations | Extract and alter the structure of objects in an image. You can use these transformations for expanding (dilating) or reducing (eroding) objects, filling holes, closing inclusions, or smoothing borders. They mainly are used to delineate objects and prepare them for quantitative inspection analysis. |
| M-skeleton | Uses an M-shaped structuring element in the skeleton function. |
N |
| neighbor | A pixel whose value affects the value of a nearby pixel when an image is processed. The neighbors of a pixel are usually defined by a kernel or structuring element. |
| neighborhood operations | Operations on a point in an image that take into consideration the values of the pixels neighboring that point. |
| nonlinear filter | Replaces each pixel value with a nonlinear function of its surrounding pixels. |
| nonlinear gradient filter | A highpass edge-extraction filter that favors vertical edges. |
| nonlinear Prewitt filter | A highpass edge-extraction filter that favors horizontal and vertical edges in an image. |
| nonlinear Sobel filter | A highpass edge-extraction filter that favors horizontal and vertical edges in an image. |
| number of planes (in an image) | The number of arrays of pixels that compose the image. A gray-level or
pseudo-color image is composed of one plane, while an RGB image is composed of three planes (one for the red component, one for the blue, and one for the green). |
| Nth order filter | Filters an image using a nonlinear filter. This filter orders (or classifies) the pixel values surrounding the pixel being processed. The pixel being processed is set to the Nth pixel value, where N is the order of the filter. |
O |
| object |
- A connected region or grouping of pixels in an image in which all pixels have intensity levels in the same range.
- A group of elements that satisfy element spacing requirements. An object is an unrecognized character. (OCR)
|
| OCR Session | Character set and parameter settings that define an instance of OCR. |
| offset | The coordinate position in an image where you want to place the origin of another image. Setting an offset is useful when performing mask operations. |
| opening | An erosion followed by a dilation. An opening removes small objects and smooths boundaries of objects in the image. |
| operators | Allow masking, combination, and comparison of images. You can use arithmetic
and logic operators in NI Vision. |
| optical character recognition (OCR) | Process of analyzing an image to detect and recognize characters/text in the image. |
| outer gradient | Finds the outer boundary of objects. |
| overlay | Regions of interest, text, and bitmaps that you can place on top of a displayed image to annotate it without modifying it. |
P |
| palette | The gradation of colors used to display an image on screen, usually defined by a color look-up table.
|
| particle | Connected region or grouping of pixels in an image in which all pixels have the same intensity level. |
| pattern | Character for which the character value requires more than one byte. (OCR) |
| pattern matching | The technique used to quickly locate a grayscale template within a grayscale image. |
| pixel | Picture element. The smallest division that makes up a digital image. For measurement tasks, optimum pixel dimensions are square (aspect ratio of 1:1, or the width equal to the height). |
| pixel calibration | Directly calibrating the physical dimensions of a pixel in an image. |
| pixel depth | The number of bits (n) used to code the intensity of a pixel. For a given n, a pixel can take 2n different values. For example, if n equals 8-bits, a pixel can take 256 different values ranging from 0 to 255. If n equals 16 bits, a pixel can take 65,536 different values ranging from 0 to 65,535 or 32,768 to 32,767. |
| pixel frame | Describes the neighborhood. For a square pixel frame, each pixel is surrounded by eight neighbors. The vertical and horizontal neighbors have a distance d from the pixel. Diagonal pixels have a slightly greater distance because they are farther away from the central pixel. For a hexagonal pixel frame, each pixel is surrounded by six neighbors. Each neighbor is at an equal distance from the central pixel. |
| PNG | Portable Network Graphic. Image file format for storing 8-bit, 16-bit, and color images with lossless compression (extension .png). |
| Power 1/Y function | Similar to a logarithmic function but with a weaker effect. |
| Power Y function | See exponential function. |
| Prewitt filter | Extracts the contours (edge detection) in gray-level values using a 3 × 3 filter kernel.
|
| probability function | Defines the probability that a pixel in an image has a certain gray-level value. |
| Processing window | Vision Assistant feature that updates the image as you change parameters. The Processing window is located on the right side of the Vision Assistant window. |
| proper-closing | A finite combination of successive closing and opening operations that you can use to fill small holes and smooth the boundaries of objects. |
| proper-opening | A finite combination of successive opening and closing operations that you can use to remove small particles and smooth the boundaries of objects. |
Q |
| quiet zone | The area containing no data that is required to surround a 2D barcode. This area is measured in module widths. |
| quantitative analysis | Obtaining various measurements of objects in an image. |
R |
| read resolution | Level of character criteria OCR uses to determine if an object matches a trained character. |
| read strategy | Method by which you determine how stringently OCR analyzes objects to determine if they match trained characters. |
| Reference window | Vision Assistant feature that displays the original version of the image (image source) as you manipulate it in the processing window. The Reference window appears in the upper left corner of the Vision Assistant window.
|
| region of interest (ROI) | An area of the image that is graphically selected from a window displaying the image. This area can be used to focus further processing. |
| resolution | The number of rows and columns of pixels. An image composed of m rows and n columns has a resolution of m´n. This image has n pixels along its horizontal axis and m pixels along its vertical axis. |
| Reverse function | Inverts the pixel values in an image, producing a photometric negative of the image. |
| rising edge | The digital signal transition from the low state to the high state. |
| RGB | Color image encoding using red, green, and blue colors. |
| RGB chunky | Color encoding scheme using red, green, and blue (RGB) color information where each pixel in the color image is encoded using 32 bits: 8 bits for red, 8 bits for green, 8 bits for blue, and 8 bits for the alpha value (unused). |
| Roberts filter | Extracts the contours (edge detection) in gray level, favoring diagonal edges. |
| ROI | Region of interest. |
| ROI tools | Collection of tools from the Tools palette that enable you to select a region of interest from an image. These tools let you select a point or line; polygon, rectangle, and oval regions; and freehand lines and areas. |
S |
| script | List of image processing and analysis functions and the parameters for each of those functions. Vision Assistant records each function and relevant parameters as you prototype your image processing application. |
| Script window | The window in which Vision Assistant displays a script. From the scripting window, you can edit, remove, or add steps and run scripts. The Script window appears in the lower left corner of the Vision Assistant window. |
| segmentation function | Fully partitions a labeled binary image into non-overlapping segments, with each segment containing a unique object. |
| segmented character | Character that OCR isolates according to specific parameters, such as thresholding, character size, and so on. |
| separation function | Separates objects that touch each other by narrow isthmuses. |
| sequence | Acquisition technique that acquires images according to settings that you specify in the acquisition property pages. |
| shape matching | Finds objects in an image whose shape matches the shape of the object specified by a template. The matching process is invariant to rotation and can be set to be invariant to the scale of the objects. |
| Sigma filter | A highpass filter that outlines edges. |
| skeleton function | Applies a succession of thinning operations to an object until its width becomes one pixel.
|
| skiz function | Obtains lines in an image that separate each object from the others and are equidistant from the objects that they separate. |
| smoothing filter | Blurs an image by attenuating variations of light intensity in the neighborhood of a pixel.
|
| snap | Acquisition techniques that acquires and displays a single image. |
| Sobel filter | Extracts the contours (edge detection) in gray-level values using a 3 × 3 filter kernel. |
| spatial calibration | Assigning physical dimensions to the area of a pixel in an image. |
| spatial filters | Alter the intensity of a pixel with respect to variations in intensities of its neighboring pixels. You can use these filters for edge detection, image enhancement, noise reduction, smoothing, and so forth. |
| spatial resolution | The number of pixels in an image, in terms of the number of rows and columns in the image.
|
| Square function | See exponential function. |
| Square Root function | See logarithmic function. |
| state | A particular set of steps that execute under certain conditions during an inspection. |
| step | A component of a Vision Builder AI inspection that performs a specific visual inspection task or supporting tasks, such as decision making and serial communication. |
| stroke character | Character that consists of continuous elements in which breaks are caused only by imperfections in the image. (OCR) |
| structuring element | A binary mask used in most morphological operations. A structuring element is used to determine which neighboring pixels contribute in the operation and to what degree. |
| sub-pixel analysis | Used to find the location of an edge or template in terms of fractions of a pixel. |
| substitution character | Character that represents unrecognized characters. Typically, the substitution character is a question mark (?). (OCR) |
| substitution error | Erroneously decoded codeword at an unknown position in a 2D barcode. |
T |
| template | Pattern that you are trying to match in an image using the Match Pattern step. A template can be a region selected from an image or it can be an entire image. |
| thickening | Alters the shape of objects by adding parts to the object that match the pattern specified in the structuring element. |
| thinning | Alters the shape of objects by eliminating parts of the object that match the pattern specified in the structuring element. |
| threshold | Separates objects from the background by assigning all pixels with intensities within a specified range to the object and the rest of the pixels to the background. In the resulting binary image, objects are represented with
a pixel intensity of 255 and the background is set to 0. |
| threshold interval | Two parameters, the lower threshold gray-level value and the upper threshold gray-level value. |
| TIFF | Tagged Image File Format. Image format commonly used for encoding 8-bit and color images (extension .tif). |
| Tools palette | Collection of tools that enable you to select regions of interest, zoom in and out, and change the image palette. |
| transition | An event that causes the inspection to move from one state to another. |
| trigger | Any event that causes or starts some form of data capture. |
| trigger polarity | Determines whether triggered events occur on the rising or falling edge of the trigger signal. |
| TTL | Transistor-transistor logic. |
V |
| vertical element spacing | Space, in pixels, between vertically adjacent elements. (OCR) |
| VI | Virtual Instrument.
- A combination of hardware and/or software elements, typically used with a PC, that has the functionality of a classic stand-alone instrument.
- A LabVIEW software module (VI), which consists of a front panel user interface and a block diagram program.
|
W |
| web inspection | The process of detecting defects in a continuous sheet of materials at production speeds. Example materials include plastic film, cloth, paper and pulp products, metal, and glass. |