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AVL.ThresholdImage_Dynamic(AvlNet.Image, AvlNet.Region, AvlNet.Region, int, int?, float?, float?, float, AvlNet.Image)

Thresholds an image relatively to the average pixel value in a local rectangular neighborhood.

Namespace:AvlNet
Assembly:AVL.NET.dll

Syntax


public static void ThresholdImage_Dynamic(
	AvlNet.Image inImage,
	AvlNet.Region inRoi,
	AvlNet.Region inSourceRoi,
	int inRadiusX,
	int? inRadiusY,
	float? inMinRelativeValue,
	float? inMaxRelativeValue,
	float inFuzziness,
	out AvlNet.Image outMonoImage
)

Parameters

inImage
Type: AvlNet.Image
Input image
inRoi
Type: AvlNet.Region
Region in which pixels are written, or null.
inSourceRoi
Type: AvlNet.Region
Region from which pixels are read, or null.
inRadiusX
Type: System.Int32
Horizontal radius of internal mean blur
inRadiusY
Type: System.Nullable<System.Int32>
Vertical radius of internal mean blur (Auto = inRadiusX), or null.
inMinRelativeValue
Type: System.Nullable<System.Single>
Minimum relative value of a pixel that is considered foreground (Auto = -INF), or null.
inMaxRelativeValue
Type: System.Nullable<System.Single>
Maximum relative value of a pixel that is considered foreground (Auto = +INF), or null.
inFuzziness
Type: System.Single
A tolerance for inMin/MaxRelativeValue that results in intermediate output values
outMonoImage
Type: AvlNet.Image

Description

The operation transforms each pixel value to the maximum or minimum level thus creating binary image. The result of the transformation depends on the relative pixel intensity:

  • Pixel values that are brighter than local average of the pixel neighbourhood by at least inMinRelativeValue and at most inMaxRelativeValue are transformed to the maximum level.
  • Other pixel values are transformed to the minimum level.

If any of the parameters inMinRelativeValue, inMaxRelativeValue is not set, it is assumed to be, accordingly, -infinity or infinity.

Pixel neighbourhood used to compute the local average is a rectangle of dimensions (2 \cdot \text{\textbf{inRadiusX} }+1) \times (2 \cdot \text{\textbf{inRadiusY} }+1) centered at the pixel being processed.

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 intensities; thus creating smooth transition between minimum and maximum values in the resulting image.

In the multichannel images the operation uses an average of channel values in each pixel, thus the resulting image is always monochromatic.

Examples

ThresholdImage_Dynamic performed on the sample image with inMinRelativeValue = 5.0, inMaxRelativeValue = auto, inFuzziness = 0.0.

ThresholdImage_Dynamic performed on the sample image with inMinRelativeValue = 5.0, inMaxRelativeValue = auto, inFuzziness = 10.0.

See also