National Instruments IMAQ Vision for Measurement Studio - Manual (Page 44)

Chapter 4 Blob Analysis
© National Instruments Corporation 4-5 IMAQ Vision for LabWindows/CVI User Manual
commonly used measurements, including the area, projection along
the x-axis and y-axis, and perimeter of each blob.
• imaqSelectParticles() —This function selects information about
blobs from the reports generated by imaqGetParticleInfo() .
Blobs that do not meet the criteria you set are filtered from the reports.
• imaqCalcCoeff() —This function uses the reports from
imaqGetParticleInfo() or imaqSelectParticles() to
calculate 50 particle measurements.
Table 4-1 lists all of the measurements that imaqCalcCoeff() returns.
Table 4-1. Particle Measurements
Measurement Description
IMAQ_AREA area of the particle in pixels
IMAQ_AREA_CALIBRATED area of the particle in user-defined units
IMAQ_NUM_HOLES number of holes within the particle
IMAQ_AREA_OF_HOLES total area of the particle holes in pixels
IMAQ_TOTAL_AREA area of the particle and its holes
IMAQ_IMAGE_AREA area of the entire image in real-world units
IMAQ_PARTICLE_TO_IMAGE ratio, expressed as a percent, of the surface area of a
particle in 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-coordinate of the center of mass
IMAQ_CENTER_MASS_Y y-coordinate of the center of mass
IMAQ_LEFT_COLUMN left x-coordinate of the bounding rectangle
IMAQ_TOP_ROW top y-coordinate of the bounding rectangle
IMAQ_RIGHT_COLUMN right x-coordinate of the bounding rectangle
IMAQ_BOTTOM_ROW bottom y-coordinate of bounding rectangle
IMAQ_WIDTH width of bounding rectangle in user-defined units
IMAQ_HEIGHT height of bounding rectangle in user-defined units
IMAQ_MAX_SEGMENT_LENGTH length of longest horizontal line segment in a particle