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.