AVL.NormalizeLocalContrast

public static void NormalizeLocalContrast
(
	AvlNet.Image inMonoImage,
	float inTargetMean,
	float inTargetVariance,
	int inUniformnessScale,
	float inBrightnessPreserveRatio,
	AvlNet.Image outImage
)

This filter resaturates every pixel of monochromatic image inMonoImage so that its neighbourhood matches approximately average of inTargetMean and variance of inTargetVariance using Wallis algorithm.

Parameter inUniformnessScale determines the radius of the neighbourhood.

Parameter inBrightnessPreserveRatio determines how much of the original brightness is kept on the resulting image.

New value of pixel is given by:

\[ P_{new} = A\ P_{old} + B \]

where

\[A = \frac{Var_{new} }{\frac{90}{CFC} + Var_{loc} } \] \[B = Mean_{new}(1 - BPR) + Mean_{loc}(BPR - A) \]

and

• \(Dev_{loc}\) and \(Mean_{loc}\) are local deviation and mean respectively, taken from the square neighbourhood of radius inUniformnessScale
• \(Dev_{new}\) and \(Mean_{new}\) are target deviation and mean respectively, inTargetVariance and inTargetMean
• CFC is Contrast Force Constant, set to \(0.9\)
• BPR is inBrightnessPreserveRatio

After the filter is run on the image, the neighbourhoods of pixels do not have desired variance and average. First reason for that is presence of constants BPR and CFC. Second reason is that forcing matching given average would require solving system of as many linear equations as there are pixels on the image.

List of possible exceptions:

Error type	Description
DomainError	Mono image expected on input in NormalizeLocalContrast.
DomainError	Region exceeds an input image in NormalizeLocalContrast.
DomainError	Not supported inMonoImage pixel format in NormalizeLocalContrast. Supported formats: 1xUInt8, 1xInt8, 1xUInt16, 1xInt16, 1xInt32, 1xReal.