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Chapter 5 Machine Vision
© National Instruments Corporation 5-25 IMAQ Visionfor LabWindows/CVI UserManual
reference pattern in all cases, you have selected a good template.
Otherwise, refine the current template, or select a better template until both
training and testing are successful.
Finding Points Using Color Location
Color location algorithms provide aquick way to locate regions inan image
with specific colors.
Use color location when your application:
• Requires the location and the number of regions in an image with their
specific color information
• Relies on the cumulative color information in the region, instead of the
color arrangement in the region
• Does not require the orientation of the region
• Does not always require the location with sub-pixel accuracy
• Does not require shape information for the region
Follow these general steps to find features in an image using color location:
1. Define a reference pattern in the form of a template image.
2. Use the reference pattern to train the color location algorithm with
imaqLearnColorPattern()
.
3. Define an image or an area of an image as the search area. A small
search area reduces the time to find the features.
4. Set the
featureMode
element of the
imaqMatchColorPattern()
options parameter to
IMAQ_COLOR_FEATURES
.
5. Set the tolerances and parameters to specify how the algorithm
operates at run time using the options parameter of
imaqMatchColorPattern()
.
6. Test the color location algorithm on test images using
imaqMatchColorPattern()
.
7. Verify the results using a ranking method.
You can save the template image using
imaqWriteVisionFile()
.