National Instruments IMAQ Vision for LabWindows TM /CVI - Manual (Page 60)

Chapter 5 Performing Machine Vision Tasks
IMAQ Vision for LabWindows/CVI User Manual 5-8 ni.com
Set Search Areas
You use ROIs to define search areas in your images and limit the areas in
which you perform your processing and inspection. You can define ROIs
interactively or programmatically.
Defining Regions Interactively
Complete the following steps to interactively define an ROI:
1. Use imaqConstructROI2() to display an image and the tools palette
in a window.
2. Select an ROI tool from the tools palette.
3. Draw an ROI on your image. Resize and reposition the ROI until it
specifies the area you want to process.
4. Click OK to output a descriptor of the region you selected. You can
input the ROI descriptor into many analysis and processing functions.
You can also use imaqSelectRect() and imaqSelectAnnulus() to
define ROIs. Complete the following steps to use these functions:
1. Call the function to display an image in a window. Only the tools
specific to that function are available for you to use.
2. Select an ROI tool from the tools palette.
3. Draw an ROI on your image. Resize or reposition the ROI until it
specifies the area you want to process.
Click OK to output a description of the ROI. You can use this description
as an input for the following functions.
ROI Selection Function Measurement Function
imaqSelectRect() imaqFindPattern()
imaqClampMax()
imaqClampMin()
imaqFindEdge()
imaqSelectAnnulus() imaqFindCircularEdge()
imaqFindConcentricEdge()