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AVL.GradientMagnitudeImage Method

Measures the strength of gradient at each pixel location with Sobel or Prewitt operator.

Namespace:	AvlNet
Assembly:	AVL.NET.dll

Syntax

public static void GradientMagnitudeImage(
	AvlNet.Image inImage,
	AvlNet.Region inRoi,
	AvlNet.GradientMaskOperator inOperator,
	AvlNet.MagnitudeMeasure inMeasure,
	int inScale,
	out AvlNet.Image outValueImage
)

Parameters

Name	Type	Range	Default	Description
inImage	AvlNet.Image			Input image.
inRoi	AvlNet.Region			Range of output pixels to be computed. Default value: atl::NIL, or null.
inOperator	AvlNet.GradientMaskOperator			Defines how the gradient is computed.
inMeasure	AvlNet.MagnitudeMeasure		Hypot	Defines how the gradient magnitude is computed. Default value: Hypot.
inScale	int	<1, 16>	1	Scales the resulting gradient magnitudes. Default value: 1.
outValueImage	AvlNet.Image			Gradient magnitudes of the image.

Description

The operation computes the magnitude of the intensity change at each pixel of the inImage. Firstly the selected inOperator is used to obtain two-dimensional gradient vector at each pixel. Then the magnitudes of the vectors are estimated using the inMeasure method.

Specified by inMeasure method computes magnitude (A) from horizontal gradient component (x) and vertical gradient component (y) using one of following formulas:
\[A_{Horizontal}=|x|\] \[A_{Vertical}=|y|\] \[A_{Average}=\frac{|x|+|y|}{2}\] \[A_{Sum}=|x|+|y|\] \[A_{Maximum}=Max(|x|,|y|)\] \[A_{Hypot}=\sqrt{x^{2}+y^{2} }\]

The magnitudes are multiplied by inScale factor and saturated if they exceed the greatest value of their type.

Examples

GradientMagnitudeImage performed on the sample image with inOperator = Sobel, inMeasure = Hypot.

Hardware Acceleration

This operation is optimized for SSE2 technology for pixels of type: UINT8.

This operation supports automatic parallelization for multicore and multiprocessor systems.