Hello wuliao23,
The IMAQ Edge Tool 2 VI works with a single ROI. You can learn more about ROIs in the NI Vision for LabVIEW Help, which typically installs as IMAQVision.chm to the following directory:
C:\Program Files\National Instruments\Vision\Documentation
Within the NI Vision for LabVIEW Help, refer to the Define Regions of Interest section, which is nested as follows:
NI Vision for LabVIEW Help>>NI Vision for LabVIEW Basics>>Making Grayscale and Color Measurements>>Define Regions of Interest
As you will see, you can include multiple contours within a single region of interest.
Regarding your second question, you should expect some variation in execution time. Windows is not a deterministic operating system. To reduce variation, I suggest you close other programs that may be running in the background.
Best Regards,
T. McCarty
