• Example to load square grating image and initialize Hough Tool.
• Load square grating image
• Take the Hough Transform:  Filter / Hough Transform
• Click on the transform image and select it: 
• Adjust search parameters as desired:
  • spot r! (vertical range within which to measure the Hough spot centroid).  Defaults to 3, which works for example image.
  • min pct! (Estimate of minimum vertical distance between Hough spots). 
• Search for the spot spacings:  square gratings / list spacings.
• Show spot locations using square gratings / spacing graphics on

As of Lx41, the two columns of spots are found using the vertical maximum function, rather than the vertical variance.