National Instruments IMAQ Vision for LabWindows TM /CVI - Manual (Page 43)

© National Instruments Corporation 4-1 IMAQ Vision for LabWindows/CVI User Manual
4
Performing Particle Analysis
This chapter describes how to perform particle analysis on your images.
Use particle analysis to find statistical information about particles—such as
the area, location, and presence of particles. With this information, you can
perform many machine vision inspection tasks, such as detecting flaws
on silicon wafers or detecting soldering defects on electronic boards.
Examples of how particle analysis can help you perform inspection tasks
include locating structural defects on wood planks or detecting cracks on
plastic sheets.
Figure 4-1 illustrates the steps involved in performing particle analysis.
Figure 4-1. Steps to Performing Particle Analysis
Create a Binary Image
Threshold your grayscale or color image to create a binary image. Creating
a binary image separates the objects that you want to inspect from the
background. The threshold operation sets the background pixels to 0 in the
binary image while setting the object pixels to a non-zero value. Object
pixels have a value of 1 by default, but you can set the object pixels to any
value you choose.
You can use different techniques to threshold your image. If all the
objects of interest in your grayscale image fall within a continuous range
of intensities and you can specify this threshold range manually, use
imaqThreshold() to threshold your image.
Create a Binary Image
Improve a Binary Image
Make Particle Measurements
in Pixels or Real-World Units