CENTROID Function (PV-WAVE Extreme Advantage)

Calculates the centroid of a binary region in an image.

Usage

result = CENTROID(image, pixels)

Input Parameters

image—A 2D array containing a region.

pixels—A long array containing the element numbers of the pixels that compose the region pixels in image. These pixels compose the region for which the centroid is calculated.

Returned Value

result—A long scalar value that is the element number in image of the centroid of the region.

Keywords

None.

Discussion

The centroid of a binary region, also known as the center of gravity, is a measure of the region’s center. The centroid is expressed in pixel-coordinate values and is calculated as the ratio of the first-order to the zeroth-order spatial moments:

centroidx = M(1, 0)/M(0, 0)

centroidy = M(0, 1)/M(0, 0)

The returned value, result is the element number (n, m) in the image array, such that:

centroid = centroidx + centroidy*n

Example

Get pixels for a region in image, where the region has an amplitude of 100.

region_pixels = WHERE(image EQ 100)

result = CENTROID(image, region_pixels)

See Also

MAJOR_AXIS,  MOMENT2D,  PERIMETER