Centroid Preferences (Markers)


The Centroid Preferences page configures how centroiding is performed for markers drawn on images. This page is part of the Marker Preferences dialog used by various drawing commands. This is a generic dialog. The title and set of enabled controls that appear on the page depend upon the parent procedure.

Centroid First Point

Check this box to centroid the starting point, or only point, used for locating the marker.

Centroid Last Point

Check this box to centroid the ending point used for locating the marker. This applies to lines

Negative/Positive

Selects whether to centroid on positive-going values (peaks) or negative-going values (valleys).

Sample Radius

Specify the radius, in pixels, used for computing the centroid (first point and last point).

Track Centroid

Check this box to track the centroid position of the first (or only) point when tracking the marker through an image set.

Track Centroid Endpoint

Check this box to track the centroid position of the last point when tracking the marker through an image set.

Centroid After Move

Check this box to centroid the marker after re-positioning it in Move mode.

Search Radius

Enter the radius, in pixels, used for tracking the marker through an image set.

Using preferences here, the marker can be centroided at its beginning or ending point, or at both points or not at all. The meaning if the centroid parameters is as for other cases where centroiding is used. For example, see the Centroid Preferences for measuring images.

Choosing Sample Radius and Tracking Radius

Centroiding on Positive and Negative Points

Centroid positions are computed using image data, not the screen display. Choose Positive points or Negative points based upon the type of object to measure rather than the palette or other image display attributes. For modern, inherently digital images, you will almost always choose Positive points. For scanned photographs, however, you may be working with a negative image and would choose the NegativePoints option.

Saving Changes

Set the preferences as desired, then accept the changes by clicking [Apply].

Related Topics

Marker Preferences Dialog, Drawing Preferences, Command Toolbars