Leginon

h1. Edge Hole Finder Set-up

Most steps in this original hole finder are identical to that of JAHC holefinder used in MSI-T application.  Only the edge and template steps are different since edge finding is performed before using an artificial ring template to create the correlation image used in the later steps.

h2. Edge>

A good combination of parameters show the edges of holes well with minimal thresholded "edge" from random features.

 *  Select the Edge Display Selection before opening the Edge Display Settings window.

 *  Choose an edge detection Threshold and press "Test". "Test" should be done every time a parameter is changed to check its effect.

 *  Adding a proper low pass filter can sometimes reduce the fragmented appearance of the edge image.

 *  Increase the Threshold if too many edges are shown in the edge image.

 *  Use the ruler tool to measure the average inner and outer hole diameters for preparation on template correlation.

h2. Template>

A good template gives a sharp correlation at the center of the holes.

 *  Select the Template Display Selection before opening the Template Display Settings window.

 *  Click Add (Rings) and enter the inner and outer hole diameters that were measured in the previous section. (Only one set of hole diameters should be in the list. If a set already exists, click Edit instead of entering the measure hole diameters.)

 *  Choose a correlation method. "cross" correlation is the typical for high contrast images. "phase" correlation works better with weak hole edges (i.e., thick ice) but should be used with a low pass filter. For example, increasing the filter pixel size can eliminating scattered peaks.

 *  "Test" these parameters and adjust, normally, the template diameters for sharpest correlation peaks at the center of the holes and exit the setting window.

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[[Summary of this application|< Summary of this applicaiont]]

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