You should not have to perform the image threshold in order to use the Match Color Pattern. The only VI that you have to call before this VI is the IMAQ Learn Color Pattern VI. This is where you learn the pattern that you will search for with the pattern match function. There are several example VIs that you can look at that ship with Vision. These examples can be found at:
C:\Program Files\National Instruments\LabVIEW 7.1\examples\Vision\2. Functions\Color Pattern Matching\Color Pattern Matching Example.llb
C:\Program Files\National Instruments\LabVIEW 7.1\examples\Vision\3. Applications\Fusebox Inspection Example.llb
C:\Program Files\National Instruments\LabVIEW 7.1\examples\Vision\3. Applications\Blister Pack Inspection Example.llb
Take a look at those examples and let me know if you have any additional questions.
Course Development Engineer