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Module: FoundationBasic

Thresholds an image with a hysteresis, i.e. with a lower threshold for neighboring pixels.

Name Type Range Description
Input value inImage Image Input image
Input value inRoi Region* Region of interest
Input value inMinValue Real* Minimum value of a pixel that is considered foreground (Auto = -INF)
Input value inMaxValue Real* Maximum value of a pixel that is considered foreground (Auto = +INF)
Input value inHysteresis Real 0.0 - Defines how much the threshold criteria are lowered for pixels neighboring with other foreground pixels
Output value outMonoImage Image


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.

Hardware Acceleration

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:

Error type Description
DomainError Region exceeds an input image in ThresholdImage_Hysteresis.

Complexity Level

This filter is available on Advanced Complexity Level.

Filter Group

This filter is member of ThresholdImage filter group.

See Also

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