Centroid Preferences
The Centroid Preferences page is a member of the Mira Preferences dialog. Use this preferences page to setup the way centroid positions are measured. These preferences are used for measuring centroid positions in a single image or an Image Set.
To open the Centroid Preferences page, open the Mira Preferences dialog and select the Centroid tab.
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Centroid on |
Selects the direction of intensity profile used for calculating centroid positions. This is measured from the pixel values and is not affected by the choice of display settings, such as the palette or contrast. |
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Positive/Negative points |
Selects whether to centroid on positive-going values (peaks) or negative-going values (valleys). |
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Sample Radius |
Defines the distance from the target point within which pixel data are used to compute the centroid position. A reasonable radius value is approximately half the diameter of a point source image. |
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Tracking Radius |
Defines the maximum distance from the current position that Mira will search in the next image to lock onto a new position. This is only used when tracking objects through an Image Set. |
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Track Centroids |
Controls the duplication of markers when the positions are "tracked" through an image set. If this option is checked, the positions are centroided in every image. |
The Sample Radius defines the distance from the target point within which points are used to compute the centroid position. A reasonable starting point for choosing a value is 2 times the FWHM (note that FWHM is a diameter and this parameter is a radius).
The Tracking Radius is used when computing the centroid of an Image Set. This value defines the maximum offset distance Mira will search in the next image to lock onto a new centroid position.
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tip |
Centroid positions are computed using image data, not the screen display. Choose Positiveor Negative based upon the type of object to measure rather than the palette or other image display attributes. |
Set the preferences as desired, then accept the changes by doing the following:
To change only the active Image Window, click [Apply] or [OK].
To change for all future Image Windows, click [Default].
When you are finished, close the Mira Preferences dialog.
Centroid Measurements, Measuring Images, Mira Preferences dialog