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Creates a region containing image pixels which belongs to specified region in HSV, HSL or HSI space.

Name Type Range Description
inRgbImage Image
inRoi Region* Range of pixels to be processed
inColorModel HSxColorModel Selected color model
inBeginHue Integer 0 - 255 Lowest acceptable Hue; if higher than inEndHue, then range wrapping is used
inEndHue Integer 0 - 255 Highest acceptable Hue, if lower than inBeginHue, then range wrapping is used
inMinSaturation Integer* 0 - 255
inMaxSaturation Integer* 0 - 255
inMinBrightness Integer* 0 - 255 Minimum brightness; denotes V, L or I, depending on inColorModel
inMaxBrightness Integer* 0 - 255 Maximum brightness; denotes V, L or I, depending on inColorModel
outRegion Region Output region
diagHSxImage Image Diagnostic image in HSx color space


For input inRgbImage only pixel formats are supported: 3⨯uint8.

Read more about pixel formats in Image documentation.


Extraction of a region characterized with a specific color.


The operation is a cousin of ThresholdImage_HSx yet it computes a region instead of an image. The three-channel inRgbImage is considered to be encoded using RGB color representation. Each of the image pixel is internally converted to HSx (HSV, HSL or HSI) color representation and then examined. The resulting region contains only those pixels of the input image, which meets all of the following conditions:

  • Value of the Hue parameter is in cyclic range (inBeginHue, inEndHue).
  • Value of the Saturation parameter is in range (inMinSaturation, inMaxSaturation).
  • Value of the Value parameter is in range (inMinBrightness, inMaxBrightness).

If any of the parameters inMinSaturation, inMinBrightness is not set, it is assumed to be -infinity.

If any of the parameters inMaxSaturation, inMaxBrightness is not set, it is assumed to be infinity.


  • Choose inColorModel taking into account accuracy and execution speed (HSV is the fastest, HSI is usually the most accurate).
  • Define the range of HSV/HSL/HSI values that best separates the foreground and background pixels. Analyze the results on the outRegion output.


Description of usage of this filter can be found in examples and tutorial: Rubber Ring (Simple).

ThresholdToRegion_HSx performed on the sample image with inColorModel = HSV, inBeginHue = 0.0, inEndHue = 10.0, inMinSaturation = 120.0, inMinBrightness = 70.0.

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 Not a 3-channel and 8-bit image in ThresholdToRegion_HSx.
DomainError Region exceeds an input image in ThresholdToRegion_HSx.
DomainError Not supported inRgbImage pixel format in ThresholdToRegion_HSx.

Complexity Level

This filter is available on Basic Complexity Level.

Filter Group

This filter is member of ThresholdToRegion filter group.

See Also

  • ThresholdImage_HSx – Transforms each pixel value to minimum or maximum depending on whether it belongs to specified region in the HSV, HSL or HSI color space.