National Instruments IMAQ Vision for Measurement Studio H

Glossary

IMAQVision for LabWindows/CVI User Manual G-8 ni.com

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 Removesor 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

Attenuatesor removes (truncates) low frequencies present in the frequency

domain of the image. A highpass frequency filtersuppresses inform ation

related to slowvariations of light intensities in the spatial image.

highpass truncation Removesall frequency information below a certain frequency.

histogram Indicates the quantitativedistribution of the pixels of an image per

gray-levelvalue.

histogram

equalization

Transformsthe 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.

histogram inversion Finds the inverse of an image. The histogram of a reversed image is equal

to the original histogram flipped horizontally around the center of the

histogram.

hit-miss function Locatesobjects in the image similar to the pattern defined in the structuring

element.

hole fillingfunction Fillsall holes in objects that are present in a binary image.

HSI Color encoding scheme in Hue, Saturation, and Intensity.

HSL Color encoding scheme using Hue, Saturation, and Luma information

whereeach image in the pixelis encoded using 32 bits: 8 bits for hue,

8 bits for saturation, 8 bits for luma, and 8 bits for the alpha channel.

HSV Colorencoding scheme in Hue, Saturation, and Value.

hue Represents the dominant color of a pixel. The hue function is a continuou s

function that coversall the possible colors generated using the R, G, and

Bprimaries.Seealso RGB.

Contents

Main IMAQ Page Important Information Warranty Copyright Trademarks WARNINGREGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS Conventions Contents Chapter 1 Introduction to IMAQ Vision Chapter 2 Getting Measurement-Ready Images Chapter 3 Grayscale and Color Measurements Chapter 4 Blob Analysis Chapter 5 Machine Vision Page Introduction to IMAQ Vision About IMAQ Vision Documentation and Examples Application Development Environments IMAQ Vision Function Tree Page IMAQ Machine Vision Function Tree Creating IMAQ Vision Applications Chapter1 Introductionto IMAQ Vision Figure1-2. InspectionSteps for Building a Vision Application IMAQVision for LabWindows/CVI User Manual 1-6 ni.com Getting Measurement-Ready Images Set Up Your Imaging System Calibrate Your Imaging System Create an Image Page Source and Destination Images AcquireorReadanImage Acquiring an Image Reading a File Converting an Array to an Image Display an Image Attach Calibration Information Analyze an Image Improve an Image Lookup Tables Filters Convolution Filter Nth Order Filter Grayscale Morphology FFT Page Complex Image Operations Grayscale and Color Measurements Define Regions of Interest Interactively Defining Regions Page Page Page Page Programmatically Defining Regions Defining Regions with Masks Measure Grayscale Statistics Measure Color Statistics Figure3-4. Primary Components of a Color Image Comparing Colors Learning Color Information Choosing the Right Color Information Specifying the Color Information to Learn Using the Entire Image Using a Region in the Image Using Multiple Regions in the Image Choosing a Color Representation Sensitivity Ignoring Learned Colors Blob Analysis Correct Image Distortion Create a Binary Image Improve the Binary Image Removing Unwanted Blobs Separating TouchingBlobs Improving Blob Shapes Make Particle Measurements Page Page Convert Pixel Coordinates to Real-World Coordinates Machine Vision Locate Objects to Inspect UsingEdgeDetectiontoBuildaCoordinateTransform Page Using Pattern Matching to Build a Coordinate Transform Page Chapter5 MachineVision NationalInstruments Corporation 5-7 IMAQVision for LabWindows/CVI User Manual ChoosingaMethodtoBuildtheCoordinateTransform Figure5-4. Buildinga Coordinate Transform Set Search Areas Interactively Defining Regions Programmatically Defining Regions Find Measurement Points Finding Features Using Edge Detection Finding Lines or Circles Figure5-5. Findinga Straight Feature Finding Edge Points Along One Search Contour Finding Edge Points Along Multiple Search Contours Finding Points Using Pattern Matching Defining and Create Good TemplateImages Symmetry Feature detail Positional information Background information Trainingthe Pattern Matching Algorithm Defining a Search Area Setting Matching Parameters and Tolerances Match Mode Minimum Contrast Rotation Angle Ranges Testingthe Search Algorithm on Test Images Using a Ranking Method to Verify Results Finding Points Using Color Pattern Matching Defining and Creating Good Color TemplateImages Color Information Symmetry Feature Detail Positional Information Trainingthe Color Pattern Matching Algorithm Defining a Search Area Setting Matching Parameters and Tolerances Color Sensitivity Search Strategy Color Score Weight Minimum Contrast Rotation Angle Ranges Testingthe Search Algorithm on Test Images Finding Points Using Color Location Convert Pixel Coordinates to Real-World Coordinates Make Measurements Distance Measurements Analytic Geometry Measurements Instrument Reader Measurements Display Results Page Calibration Perspective and Nonlinear Distortion Calibration Defining a Calibration Template Defining a Reference Coordinate System Page Page Learning Calibration Information Specifying Scaling Factors Choosing a Region of Interest Choosing a Learning Algorithm Using the Learning Score Learning the Error Map Learning the Correction Table Setting the Scaling Method Calibration Invalidation Simple Calibration Save Calibration Information Attach Calibration Information A Technical Support Resources Web Support NI Developer Zone Customer Education System Integration Worldwide Support Glossary Numbers/Symbols A B C Page D E F G H I Page J K L M N O P Page Q R S T Page Index A B C D E F G H I Page Page L M N O P R S T V W Z