I believe that IMAQ Particle Filter has a limit of 32767 blobs (16 bits). Your image obviously contains more than this number. Exceeding this limit used to crash LabVIEW back when using IMAQ Vision 6. I have not tested it in version 7 yet. I'd be interested to know if it's been fixed (at least to the point of not crashing LV). In any case, you are better off using a median filter to filter out salt and pepper noise. You may want to do this on the grayscale image before you get to the thresholded image.
Ken Pietrzak
DCI
www.displaycheck.com
