Glossary

NI Vision Builder AI Vision Assistant

Glossary

Numbers
1D	One-dimensional.
2D	Two-dimensional.
3D	Three-dimensional.
3D view	Displays the light intensity of an image in a three-dimensional coordinate system, where the spatial coordinates of the image form two dimensions and the light intensity forms the third dimension.
A
area threshold	Detects objects based on their size.
arithmetic operators	Multiply, divide, add, subtract, and remainder operations you can perform on images.
auto-median function	A function that uses dual combinations of opening and closing operations to smooth the boundaries of objects.
B
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) that touch the image border in a binary image.
Builder file	Vision Assistant script file. Builder files are ASCII text files that list the processing functions and relevant parameters for an image processing algorithm that you created in Vision Assistant.
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.
circle function	Detects circular objects in a binary image.
class	A category representing a collection of similar samples.
classification	An operation that assigns samples to classes based on predefined features.
classification score	Degree of certainty that a sample is assigned to one class instead of other classes.
classifier	A function or VI that assigns a sample to a class.
closing	A dilation followed by an erosion. A closing fills small holes in objects and smoothes 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.
color images	Images containing color information, usually encoded in the RGB form.
complex images	Save information obtained from the FFT of an image. The complex numbers that compose the FFT plane are encoded in 64-bit floating-point values: 32 bits for the real part and 32 bits for the imaginary part.
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	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.
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 device that can contain multiple channels and conversion devices.
differentiation filter	Extracts the contours (edge detection) in gray level.
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.
driver	Software that controls a specific hardware device, such as a data acquisition device.
E
edge	Defined by a sharp change (transition) in the pixel intensities in an image or along an array of pixels.
edge contrast	The difference between the average pixel intensity before and the average pixel intensity after the edge.
edge steepness	The number of pixels that corresponds to the slope or transition area of an edge.
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.
erosion	Reduces the size of an object along its boundary and eliminates isolated points in the image.
exponential function	Decreases the brightness and increases the contrast in bright regions of an image, and decreases contrast in dark regions.
F
feature	A measurement from or attribute of a sample.
feature vector	A 1D array in which each element represents a different feature of a sample.
FFT	Fast Fourier Transform. A method used to compute the Fourier transform of an 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.
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.
grab	Acquisition technique that acquires and displays a continuous sequence of images using an image acquisition device. Use this acquisition technique when you need to focus the 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.
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.
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
identification score	Degree of similarity between a sample and members of the class to which the sample is assigned.
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 Browser	Vision Assistant feature that displays all of the images currently loaded. Through the Image Browser, you can select an image that you want to process by double clicking it.
image buffer	Memory location used to store images.
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 that 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 Source Image, the image reverts to the original image, and any processing done on the image prior to selecting Image Source is cancelled.
inner gradient	Finds the inner boundary of objects.
inspection functions	Detects specific features in an image. The features detected include edges, peaks, and rotational shifts.
intensity range	Defines the range of gray-level values in an object of an 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	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	A morphology operation that identifies each object in a binary image and assigns a unique pixel value to all the pixels in an object. This process is useful for identifying the number of objects in the image and giving each object a unique pixel intensity.
LabVIEW	Laboratory Virtual Instrument Engineering Workbench. Program development environment based on the G programming language. LabVIEW is 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.
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.
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
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.
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.
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.
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.
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.
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).
O
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 smoothes boundaries of objects in the image.
operators	Allow masking, combination, and comparison of images. You can use arithmetic and logic operators in NI Vision.
outer gradient	Finds the outer boundary of objects.
P
palette	The gradation of colors used to display an image on screen, usually defined by a color look-up table.
particle	A connected region or grouping of pixels in an image in which all pixels have the same intensity level. You can identify particles in binary images as black objects on white backgrounds.
particle analysis	A series of processing operations and analysis functions that produce some information about the particles in an image.
pattern matching	The process of locating a grayscale template in a grayscale image.
picture element	An element of a digital image. Also called pixel.
pixel	Picture element.
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).
Prewitt filter	Extracts the contours (edge detection) in gray-level values using a 3 × 3 filter kernel.
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
quantitative analysis	Obtaining various measurements of objects in an image.
R
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	An area of the image that is graphically selected from a window displaying the image. This area can be used to focus further processing. Also called ROI.
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.
RGB	Color image encoding using red, green, and blue colors.
Roberts filter	Extracts the contours (edge detection) in gray level, favoring diagonal edges.
ROI	Region of interest.
ROI tools	Collection of tools 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
sample	An object in an image that you want to classify.
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 the image processing application.
Script window	The window in which Vision Assistant displays a script. From the scripting window, you can edit or remove steps and run scripts.
segmentation function	Fully partitions a labeled binary image into non-overlapping segments, with each segment containing a unique object.
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 you can set it to be invariant to the scale of the objects.
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 technique 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.
Square function	See exponential function.
Square Root function	See logarithmic function.
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.
T
template	Pattern, shape, or color that you are trying to match in an image using the Pattern Matching, Shape Matching, or Color Matching functions. 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.
TIFF	Tagged Image File Format. Tagged Image File Format. Image format commonly used for encoding 8-bit and color images (extension .tif).
toolbar	Collection of tools that enable you to select regions of interest, zoom in and out, and change the image palette. These tools are located in the toolbar at the top of the Vision Assistant dialog box.
W
watershed	A technique used to segment an image into multiple regions.

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