imaqLocalThreshold

Usage

int imaqLocalThreshold(Image* dest, const Image* source, unsigned int windowWidth, unsigned int windowHeight, LocalThresholdMethod method, double deviationWeight, ObjectType type, float replaceValue);

Purpose

Automatically thresholds an image into a binary image based on the requested local adaptive thresholding method.

Image Types Supported

IMAQ_IMAGE_U8, IMAQ_IMAGE_I16

Parameters

Name	Type	Description
dest	Image*	The destination image.
source	const Image*	The image to threshold.
windowWidth	unsigned int	The width of the rectangular window around the pixel on which the function performs the local threshold. This number must be at least 3 and cannot be larger than the width of source.
windowHeight	unsigned int	The height of the rectangular window around the pixel on which the function performs the local threshold. This number must be at least 3 and cannot be larger than the height of source.
method	LocalThresholdMethod	Specifies the local thresholding method the function uses.
deviationWeight	double	Specifies the k constant used in the Niblack local thresholding algorithm, which determines the weight applied to the variance calculation. Valid k constants range from 0 to 1. Settings this value to 0 will increase the performance of the function because the function will not calculate the variance for any of the pixels. The function ignores this value if method is not set to IMAQ_NIBLACK.
type	ObjectType	Specifies the type of objects for which you want to look.
replaceValue	float	Specifies the replacement value the function uses for the pixels of the kept objects in the destination image.

Return Value

Type	Description
int	On success, this function returns a non-zero value. On failure, this function returns 0. To get extended error information, call imaqGetLastError().

Parameter Discussion

windowWidth, windowHeight—The window should be sized as large as possible but small enough that each window contains pixels under similar lighting conditions. The function will produce inconsistent results for windows that contain uniform pixel values.