National Instruments IMAQ Vision for LabWindows TM /CVI Display Results

Chapter 5 Performing Machine Vision Tasks

© National Instruments Corporation 5-31 IMAQ Vision for LabWindows/CVI User Manual

By default, imaqReadDataMatrixBarcode() assumes the barcode cells

are square. If the barcodes you need to read have round cells, set the

cellShape element of the options parameter to IMAQ_ROUND_CELLS.

Note Specify round cells only if the Data Matrix cells are round and have clearly defined

edges. If the cells in the matrix touch one another, you must set cellShape to

IMAQ_SQUARE_CELLS.

By default, imaqReadDataMatrixBarcode() assumes the shape of the

barcode is square. If the shape of your barcode is rectangular, set the

barcodeShape element of the options parameter to

IMAQ_RECTANGULAR_BARCODE_2D.

Note Setting the barcodeShape element to IMAQ_RECTANGULAR_BARCODE_2D when

the barcode you need to read is square reduces the reliability of your application.

By default, imaqReadDataMatrixBarcode() automatically detects the

type of barcode to read. You can improve the performance of the your

function by specifying the type of barcode in your application. IMAQ

Vision supports Data Matrix types ECC 000 to ECC 140, and ECC200.

Reading PDF417 Barcodes

Use imaqReadPDF417Barcode() to read values encoded in a PDF417

barcode.

imaqReadPDF417Barcode() can locate automatically one or multiple

PDF417 barcodes in an image. However, you can improve the inspection

performance by locating the barcodes using one of the techniques described

in this chapter. Then pass in the ROI location to

imaqReadPDF417Barcode().

Tip If you need to read only one barcode per image, set the searchMode parameter to

IMAQ_SEARCH_SINGLE_CONSERVATIVE to increase the speed of your application.

Display Results

You can overlay the results obtained at various stages of you inspection

process on the window that displays your inspection image. The software

attaches the information that you want to overlay to the image, but it does

not modify the image. The overlay appears every time you display the

image in an external window.

Contents

Main IMAQ Page Important Information Warranty Copyright Trademarks Patents Contents About This Manual Chapter 1 Introduction to IMAQ Vision Chapter 2 Getting Measurement-Ready Images Chapter 3 Making Grayscale and Color Measurements Chapter 4 Performing Particle Analysis Chapter 5 Performing Machine Vision Tasks Chapter 6 Calibrating Images Page About This Manual Conventions Related Documentation IMAQ Vision NI Vision Assistant NI Vision Builder for Automated Inspection Other Documentation Introduction to IMAQ Vision About IMAQ Vision Application Development Environments IMAQ Vision Function Tree IMAQ Machine Vision Function Tree Creating IMAQ Vision Applications Chapter 1 Introduction to IMAQ Vision National Instruments Corporation 1-5 IMAQ Vision for LabWindows/CVI User Manual Chapter 1 Introduction to IMAQ Vision IMAQ Vision 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 Acquire or Read an Image 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 Complex Image Operations Making Grayscale and Color Measurements Define Regions of Interest Defining Regions Interactively Page Page Page Tools Palette Transformation Defining Regions Programmatically Defining Regions with Masks Measure Grayscale Statistics Measure Color Statistics Figure 3-4. Primary Components of a 32-Bit Color Image Figure 3-5. Primary Components of a 64-Bit Color Image Note You can also use imaqExtractColorPlanes() to process the red, green, and blue components of a 64-bit image. Comparing Colors Learning 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 Performing Particle Analysis Create a Binary Image Improve the Binary Image Removing Unwanted Particles Separating Touching Particles Improving Particle Shapes Make Particle Measurements Page Page Page Page Page Page Performing Machine Vision Tas ks Locate Objects to Inspect Page Using Edge Detection to Build a Coordinate Transform Page Using Pattern Matching to Build a Coordinate Transform Chapter 5 Performing Machine Vision Tasks National Instruments Corporation 5-7 IMAQ Vision for LabWindows/CVI User Manual Choosing a Method to Build the Coordinate Transform Figure 5-4. Building a Coordinate Transform Set Search Areas Defining Regions Interactively Defining Regions Programmatically Find Measurement Points Finding Features Using Edge Detection Finding Lines or Circles Finding Edge Points Along One Search Contour Finding Edge Points Along Multiple Search Contours Finding Points Using Pattern Matching Defining and Creating Good Template Images Symmetry Feature Detail Positional Information Background Information Training the Pattern Matching Algorithm Defining a Search Area Setting Matching Parameters and Tolerances Match Mode Minimum Contrast Rotation Angle Ranges Testing the Search Algorithm on Test Images Using a Ranking Method to Verify Results Finding Points Using Color Pattern Matching Defining and Creating Good Color Template Images Color Information Symmetry Feature Detail Positional Information Training the 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 Testing the 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 Identify Parts Under Inspection Classifying Samples Reading Characters Reading Barcodes Reading 1D Barcodes Reading Data Matrix Barcodes Reading PDF417 Barcodes Display Results Page Page Calibrating Images Perspective and Nonlinear Distortion Calibration Defining a Calibration Template Defining a Reference Coordinate System 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 and Professional Services Glossary Numbers A B Page C D E F G H I Page J K L Page M N O P Q R S T V Index Numerics A B C D E F G H I K L M N O P R S T U V W