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Chapter 4 Performing Particle Analysis
IMAQ Vision for Visual Basic User Manual 4-4 ni.com
Improving Particle Shapes
Use CWIMAQVision.FillHole to fill holes in the particles. Use
CWIMAQVision.Morphology to perform a variety of operations on the
particles. You can use the Open, Close, Proper Open, Proper Close, and
auto-median operations to smooth the boundaries of the particles. Open and
Proper Open Smooth the boundaries of the particle by removing small
isthmuses, while close widens the isthmuses. Close and Proper Close fill
small holes in the particle. Auto-median removes isthmuses and fills holes.
For more information about these operations, refer to Chapter 9, Binary
Morphology, in the IMAQ Vision Concepts Manual.
Make Particle Measurements
After you create a binary image and improve it, you can make particle
measurements. With these measurements you can determine the location of
particles and their shape features. Use the following methods to perform
particle measurements:
•
CWIMAQVision.ParticleReport—This method returns a
CWIMAQParticleReport object, which contains, for each particle,
nine of the most commonly used measurements, including the particle
area, bounding rectangle, and center of mass. The bounding rectangle
is returned as one measurement, but contains four measurement
elements. The center of mass is returned as one measurement, but
contains two elements.
•
CWIMAQVision.ParticleMeasurement—This method takes the
measurement you want to apply to all particles, and returns an array
that contains the specified measurement for each particle.
Table 4-1 lists all of the measurements that
CWIMAQVision.ParticleMeasurement returns.
Table 4-1. Measurement Types
Measurement Description
cwimaqMeasurementArea Area of the particle.
cwimaqMeasurementAreaByImageArea Percentage of the particle Area covering
the Image Area.
cwimaqMeasurementAreaByParticleAndHolesArea Percentage of the particle Area in
relation to its Particle & Holes’ Area.