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

• Pixel values in range [inMinValue, inMaxValue] are transformed to the maximum level.
• Pixel values lower than inMinValue-inHysteresis or higher than inMaxValue+inHysteresis are transformed to the minimum level.
• Pixel values in range [inMinValue-inHysteresis, inMinValue) or in range (inMaxValue, inMaxValue+inHysteresis] are transformed to the maximum if (and only if) in the processed image there is a path of consecutive pixels of value in range [inMinValue-inHysteresis, inMaxValue+inHysteresis] that connects the pixel being considered and any pixel with value in range [inMinValue, inMaxValue].

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

• Define inMinValue to extract bright objects (brighter than the specified value).
• Define inMaxValue to extract dark objects (darker than the specified value).
• Use inHysteresis to allow weaker threshold for pixels neighboring with already extracted ones.

ThresholdImage_Hysteresis performed on the sample image with inMinValue = 110.0, inMaxValue = Nil, inHysteresis = 15.0.

Pixels of the sample image brighter than 110.0.

Pixels of the sample image brighter than 95.0.

This operation supports automatic parallelization for multicore and multiprocessor systems.

This filter can throw an exception to report error. Read how to deal with errors in Error Handling.

List of possible exceptions:

This filter is available on Advanced Complexity Level.

This filter is member of ThresholdImage filter group.

• ThresholdToRegion – Creates a region containing image pixels with values within the specified range.