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ErodeRegion

Header:	FIL.h
Namespace:	fil
Module:	FoundationBasic

Performs a morphological erosion on a region using a predefined kernel.

Applications: Making the region thinner or removing small parts.

Syntax

void fil::ErodeRegion
(
	const fil::Region& inRegion,
	fil::KernelShape::Type inKernel,
	int inRadiusX,
	ftl::Optional<int> inRadiusY,
	fil::Region& outRegion
)

Parameters

Name	Type	Range	Default	Description
inRegion	const Region&			Input region
inKernel	KernelShape::Type			Kernel shape (predefined)
inRadiusX	int	0 -	1	Nearly half of the kernel's width (2*R+1)
inRadiusY	Optional<int>	0 -	NIL	Nearly half of the kernel's height (2*R+1), or same as inRadiusX
outRegion	Region&			Output region

Description

The operation performs a morphological erosion, which is a basic tool used for region shrinking. Similarly to other region morphology operations, erosion is conducted using a shape called kernel (or structuring element). The kernel is repeatedly centered at each location within the dimensions of the input region. Then, pixel location L is added to the resulting region if and only if all of the input region pixels lies inside the kernel centered at this (L) location.

The input parameter inKernel allows to choose the shape of a kernel, while parameters inRadiusX, inRadiusY allow to determine its dimensions. For instance:

inKernel = Ellipse together with inRadiusX = inRadiusY results in shrinking performed equally in all directions.
Setting inRadiusX to higher value than inRadiusY results in shrinking performed more significantly along horizontal axis.

Hints

Increase inRadiusX to make the output region thinner.
Change inKernel to Ellipse to make the filter work equally strongly in each direction (execution will be slower).

Examples

ErodeRegion run with inKernel = Ellipse of dimensions inRadiusX = 3, inRadiusY = 3.

Errors

List of possible exceptions:

Error type	Description
DomainError	Unsupported kernel in ErodeRegion.