National Instruments IMAQ Vision for Measurement Studio - Manual (Page 48)

Chapter 5 Machine Vision
IMAQ Vision for LabWindows/CVI User Manual 5-2 ni.com
Figure 5-1 illustrates the basic steps involved in performing machine
vision. Diagram items enclosed with dashed lines are optional steps.
Figure 5-1. Steps to Performing Machine Vision
Locate Objects to Inspect
In a typical machine vision application, you extract measurements from
regions of interest rather than the entire image. To use this technique, the
parts of the object you are interested in must always appear inside the
regions of interest you define.
If the object under inspection is always at the same location and orientation
in the images you need to process, defining regions of interest is simple.
See the
Set Search Areas section for information about selecting a region
of interest.
Often, the object under inspection appears rotated or shifted in the image
you need to process with respect to the reference image in which you
located the object. When this occurs, the regions of interest (ROIs) need to
shift and rotate with the parts of the object in which you are interested. In
order for the ROIs to move with the object, you need to define a reference
coordinate system relative to the object in the reference image. During the
measurement process, the coordinate system moves with the object when it
Locate Objects to Inspect
Set Search Areas
Find Measurement Points
Convert Pixel Coordinates to
Real-World Coordinates
Make Measurements
Display Results