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OtsuThreshold Class |
Otsu thresholding.
Inheritance HierarchyNamespace: Accord.Imaging.Filters
Assembly: Accord.Imaging (in Accord.Imaging.dll) Version: 3.8.0
SyntaxThe OtsuThreshold type exposes the following members.
Constructors| Name | Description | |
|---|---|---|
 | OtsuThreshold |
Initializes a new instance of the OtsuThreshold class.
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Properties| Name | Description | |
|---|---|---|
 | FormatTranslations |
Format translations dictionary.
(Overrides BaseInPlacePartialFilterFormatTranslations.) |
| ThresholdValue |
Threshold value.
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Methods| Name | Description | |
|---|---|---|
| Apply(Bitmap) |
Apply filter to an image.
(Inherited from BaseInPlacePartialFilter.) |
| Apply(BitmapData) |
Apply filter to an image.
(Inherited from BaseInPlacePartialFilter.) |
| Apply(UnmanagedImage) |
Apply filter to an image in unmanaged memory.
(Inherited from BaseInPlacePartialFilter.) |
| Apply(UnmanagedImage, UnmanagedImage) |
Apply filter to an image in unmanaged memory.
(Inherited from BaseInPlacePartialFilter.) |
| ApplyInPlace(Bitmap) |
Apply filter to an image.
(Inherited from BaseInPlacePartialFilter.) |
| ApplyInPlace(BitmapData) |
Apply filter to an image.
(Inherited from BaseInPlacePartialFilter.) |
| ApplyInPlace(UnmanagedImage) |
Apply filter to an unmanaged image.
(Inherited from BaseInPlacePartialFilter.) |
| ApplyInPlace(Bitmap, Rectangle) |
Apply filter to an image or its part.
(Inherited from BaseInPlacePartialFilter.) |
| ApplyInPlace(BitmapData, Rectangle) |
Apply filter to an image or its part.
(Inherited from BaseInPlacePartialFilter.) |
| ApplyInPlace(UnmanagedImage, Rectangle) |
Apply filter to an unmanaged image or its part.
(Inherited from BaseInPlacePartialFilter.) |
| CalculateThreshold(Bitmap, Rectangle) |
Calculate binarization threshold for the given image.
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| CalculateThreshold(BitmapData, Rectangle) |
Calculate binarization threshold for the given image.
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| CalculateThreshold(UnmanagedImage, Rectangle) |
Calculate binarization threshold for the given image.
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| Equals | Determines whether the specified object is equal to the current object. (Inherited from Object.) |
 | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
| GetHashCode | Serves as the default hash function. (Inherited from Object.) |
| GetType | Gets the Type of the current instance. (Inherited from Object.) |
| MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
| ProcessFilter |
Process the filter on the specified image.
(Overrides BaseInPlacePartialFilterProcessFilter(UnmanagedImage, Rectangle).) |
| ToString | Returns a string that represents the current object. (Inherited from Object.) |
Extension Methods| Name | Description | |
|---|---|---|
 | HasMethod |
Checks whether an object implements a method with the given name.
(Defined by ExtensionMethods.) |
| IsEqual |
Compares two objects for equality, performing an elementwise
comparison if the elements are vectors or matrices.
(Defined by Matrix.) |
| To(Type) | Overloaded.
Converts an object into another type, irrespective of whether
the conversion can be done at compile time or not. This can be
used to convert generic types to numeric types during runtime.
(Defined by ExtensionMethods.) |
| ToT | Overloaded.
Converts an object into another type, irrespective of whether
the conversion can be done at compile time or not. This can be
used to convert generic types to numeric types during runtime.
(Defined by ExtensionMethods.) |
RemarksThe class implements Otsu thresholding, which is described in N. Otsu, "A threshold selection method from gray-level histograms", IEEE Trans. Systems, Man and Cybernetics 9(1), pp. 62–66, 1979.
This implementation instead of minimizing the weighted within-class variance does maximization of between-class variance, what gives the same result. The approach is described in this presentation.
The filter accepts 8 bpp grayscale images for processing.
Sample usage:
// create filter OtsuThreshold filter = new OtsuThreshold( ); // apply the filter filter.ApplyInPlace( image ); // check threshold value byte t = filter.ThresholdValue; // ...
Initial image:
Result image (calculated threshold is 97):
See Also