National Instruments IMAQ Vision for Measurement Studio - page 44

Chapter4 BlobAnalysis

©NationalInstruments Corporation 4-5 IMAQVision for LabWindows/CVI User Manual

commonly used measurements,including the area, projection along

the x-axis and y-axis, and perimeterof each blob.

•imaqSelectParticles()—Thisfunction selects information about

blobs from the reports generated by imaqGetParticleInfo().

Blobsthat do not meet the criteria you set are filtered from the reports.

•imaqCalcCoeff()—Thisfun ction uses the reports from

imaqGetParticleInfo()or imaqSelectParticles() to

calculate 50 particle measurements.

Table4-1 lists all of the measurements that imaqCalcCoeff() returns.

Table4-1. ParticleMeasurement s

Measurement Description

IMAQ_AREA areaof the particle in pixels

IMAQ_AREA_CALIBRATED areaof the particle in user-defined units

IMAQ_NUM_HOLES number of holes within the particle

IMAQ_AREA_OF_HOLES totalarea of the part icle holes in pixels

IMAQ_TOTAL_AREA areaof the particle and its holes

IMAQ_IMAGE_AREA areaof the entire imagein real-world units

IMAQ_PARTICLE_TO_IMAGE ratio,expressed as a percent, of the surface area of a

particlein relation to the image area

IMAQ_PARTICLE_TO_TOTAL ratio,expressed as a percent, of the surface area of a

particle in relation to the total area of the particle

IMAQ_CENTER_MASS_X x-coordinateof th ecen ter of mass

IMAQ_CENTER_MASS_Y y-coordinateof th ecen ter of mass

IMAQ_LEFT_COLUMN leftx-coordinate of thebounding rectangle

IMAQ_TOP_ROW top y-coordinate of the bounding rectangle

IMAQ_RIGHT_COLUMN rightx-coo rdinate of the bounding rectangle

IMAQ_BOTTOM_ROW bottom y-coordinate of bounding rectangle

IMAQ_WIDTH width of bounding rectangle in user-definedunits

IMAQ_HEIGHT heighto f bounding rectangle in user-definedunits

IMAQ_MAX_SEGMENT_LENGTH lengthof longest hor izontal line segment in a particle

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