You are here: Start » Function Reference » Image » Image Thresholding » ThresholdImage_RGB

ThresholdImage_RGB

Header:	AVL.h
Namespace:	avl
Module:	FoundationLite

Transforms each pixel value to minimum or maximum depending on whether it belongs to the specified range for each individual pixel component.

Applications: Multi-channel thresholding.

Syntax

void avl::ThresholdImage_RGB
(
	const avl::Image& inRgbImage,
	atl::Optional<const avl::Region&> inRoi,
	atl::Optional<int> inMinRed,
	atl::Optional<int> inMaxRed,
	atl::Optional<int> inMinGreen,
	atl::Optional<int> inMaxGreen,
	atl::Optional<int> inMinBlue,
	atl::Optional<int> inMaxBlue,
	atl::Optional<int> inMinAlpha,
	atl::Optional<int> inMaxAlpha,
	float inFuzziness,
	avl::Image& outMonoImage
)

Parameters

Name	Type	Range	Default	Description
inRgbImage	const Image&			Input image, usually in the RGB color space
inRoi	Optional<const Region&>		NIL	Region of interest
inMinRed	Optional<int>	0 - 255	128	Minimum for the first pixel component, usually Red (Auto = -INF)
inMaxRed	Optional<int>	0 - 255	NIL	Maximum for the first pixel component, usually Red (Auto = +INF)
inMinGreen	Optional<int>	0 - 255	128	Minimum for the second pixel component, usually Green (Auto = -INF)
inMaxGreen	Optional<int>	0 - 255	NIL	Maximum for the second pixel component, usually Green (Auto = +INF)
inMinBlue	Optional<int>	0 - 255	128	Minimum for the third pixel component, usually Blue (Auto = -INF)
inMaxBlue	Optional<int>	0 - 255	NIL	Maximum for the third pixel component, usually Blue (Auto = +INF)
inMinAlpha	Optional<int>	0 - 255	NIL	Minimum for the fourth pixel component, usually Blue (Auto = -INF)
inMaxAlpha	Optional<int>	0 - 255	NIL	Maximum for the fourth pixel component, usually Blue (Auto = +INF)
inFuzziness	float	0.0 -		Tolerance for the ranges that results in intermediate output values
outMonoImage	Image&

Requirements

For input inRgbImage only pixel formats are supported: 3⨯uint8, 4⨯uint8.

Read more about pixel formats in Image documentation.

Description

The operation transforms each pixel of three-channel inRgbImage to the maximum or minimum level thus creating binary image. The input image is considered to be encoded using RGB color representation.

Pixels meeting all of the following conditions are transformed to the maximum level:
- Intensity of the "red" channel is in range (inMinRed, inMaxRed).
- Intensity of the "green" channel is in range (inMinGreen, inMaxGreen).
- Intensity of the "blue" channel is in range (inMinBlue, inMaxBlue).
Other pixels are transformed to the maximum level.

If any of the parameters inMinRed, inMinGreen, inMinBlue is not set, it is assumed to be -infinity. If any of the parameters inMaxRed, inMaxGreen, inMaxBlue is not set, it is assumed to be infinity.

Parameter inFuzziness (set to 0 by default) allows to perform fuzzy thresholding which linearly interpolates those pixel values that differ by at most inFuzziness from the border channel intensities; thus creating smooth transition between minimum and maximum values in the resulting image.

Examples

ThresholdImage_RGB performed on the sample image with inMinRed = 120.0, inMaxGreen = 100.0, inMaxBlue = 100.0, inFuzziness = 0.0.

ThresholdImage_RGB performed on the sample image with inMinRed = 120.0, inMaxGreen = 100.0, inMaxBlue = 100.0, inFuzziness = 10.0.

Hardware Acceleration

This operation is optimized for SSSE4 (for inFuzziness = 0) technology.

This operation is optimized for AVX2 (for inFuzziness = 0) technology.

This operation is optimized for NEON technology for pixels of types: 1xUINT8 (for inFuzziness = 0), 3xUINT8 (for inFuzziness = 0).

This operation supports automatic parallelization for multicore and multiprocessor systems.

Errors

List of possible exceptions:

Error type	Description
DomainError	Not a 3-channel and 8-bit image in ThresholdImage_RGB.
DomainError	Region exceeds an input image in ThresholdImage_RGB.
DomainError	Not supported inRgbImage pixel format in ThresholdImage_RGB. Supported formats: 3xUInt8, 4xUInt8.