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RegionMoment

Header:	AVL.h
Namespace:	avl
Module:	FoundationBasic

Computes selected second-order moment of a region in regular and normalized ( divided by region area ) variant.

Syntax

void avl::RegionMoment
(
	const avl::Region& inRegion,
	avl::RegionMomentType::Type inMomentType,
	bool inCentral,
	float& outMoment,
	float& outNormMoment
)

Parameters

Name	Type	Description
inRegion	const Region&	Input region
inMomentType	RegionMomentType::Type
inCentral	bool
outMoment	float&
outNormMoment	float&

Description

The operation computes the mathematical features of a shape called moments. Those are sums computed as follows:

\[ \begin{aligned} Moment_{2,0}(R) &= \sum_{p \in R} p_x^2 \\ Moment_{1,1}(R) &= \sum_{p \in R} p_x p_y \\ Moment_{0,2}(R) &= \sum_{p \in R} p_y^2 \end{aligned} \]

The summing is conducted over region pixels, while \( p_x \) and \( p_y \) denote, accordingly, x and y coordinate of a pixel.

When inCentral parameter is set, the region is shifted before computations, so that its mass center is at location (0,0).

Hints

If the input region is not guaranteed to be non-empty, precede this filter with SkipEmptyRegion.

Errors

List of possible exceptions: