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SelectThresholdValue

Selects best threshold value using the image histogram.

Syntax

void avl::SelectThresholdValue
(
	const avl::Image& inImage,
	atl::Optional<const avl::Region&> inRoi,
	avl::ThresholdSelectionMethod::Type inMethod,
	float& outThresholdValue,
	atl::Array<float>& diagThresholdRatings,
	atl::Array<float>& diagBackgroundPixelsFraction,
	atl::Array<float>& diagForegroundPixelsFraction
)

void SelectThresholdValue
(
	Image inImage,
	Region? inRoi,
	ThresholdSelectionMethod inMethod,
	out float outThresholdValue,
	out float[] diagThresholdRatings,
	out float[] diagBackgroundPixelsFraction,
	out float[] diagForegroundPixelsFraction
)

Parameters

Name	Type	Default	Description
inImage	const Image&		Input image
inRoi	Optional<const Region&>	NIL	Range of pixels to be processed
inMethod	ThresholdSelectionMethod::Type		Method used to select the best threshold
outThresholdValue	float&		Best threshold separating background pixels from foreground pixels
diagThresholdRatings	Array<float>&		Contains ratings gained if that threshold would be chosen
diagBackgroundPixelsFraction	Array<float>&		Fraction of pixels that are darker than the index value
diagForegroundPixelsFraction	Array<float>&		Fraction of pixels that are brighter than the index value

Description

The operation estimates an intensity threshold value that discriminates foreground pixels from background pixels in inImage.

Note that to provide meaningful results it is required that the image in fact consists of foreground and background components that strongly differ in brightness.

Hints

Choose inMethod that works best in your application. None of the methods is perfect, but ClusteringOtsu is the most universal one.

Examples