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ContrastEffect Class
[Win10] Increases or decreases the contrast of an image.
Inheritance Hierarchy
SystemObject
  Microsoft.Graphics.Canvas.EffectsContrastEffect

Namespace:  Microsoft.Graphics.Canvas.Effects
Assembly:  Microsoft.Graphics.Canvas (in Microsoft.Graphics.Canvas.dll) Version: 0.0.0.0
Syntax
C#
public sealed class ContrastEffect : ICanvasEffect, 
	IGraphicsEffect, IGraphicsEffectSource, ICanvasImage, IDisposable

The ContrastEffect type exposes the following members.

Constructors
  NameDescription
Public methodContrastEffect
Initializes a new instance of the ContrastEffect class.
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Properties
  NameDescription
Public propertyBufferPrecision
Specifies what precision to use for intermediate buffers when drawing this effect.
Public propertyCacheOutput
Enables caching the output from drawing this effect.
Public propertyClampSource
Indicates whether to clamp input values to 0-1 range before contrast adjustment. Default value false.
Public propertyContrast
Amount by which to adjust the contrast of the image. Default value 0, range -1 to 1.
Public propertyName
Attaches a user-defined name string to the effect.
Public propertySource
Gets or sets the input source for Contrast effect.
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Methods
  NameDescription
Public methodDispose
Releases all resources used by the effect.
Public methodGetBounds(ICanvasResourceCreator)
Retrieves the bounds of this ContrastEffect.
Public methodGetBounds(ICanvasResourceCreator, Matrix3x2)
Retrieves the bounds of this ContrastEffect.
Public methodGetInvalidRectangles
Queries what regions of the effect output have changed since it was last drawn.
Public methodCode exampleGetRequiredSourceRectangle
Queries what part of an effect source image is needed to draw an output region.
Public methodGetRequiredSourceRectangles
Queries what parts of the effect source images are needed to draw an output region.
Public methodInvalidateSourceRectangle
Notifies the effect that one of its source images has changed.
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Remarks

This API is available on Windows 10 (Universal Windows Platform) only. It is not supported on Windows 8.1 or Phone 8.1.

The contrast function modifies each color channel value using two piecewise quadratic polynomials that meet with slope continuity at the point (0.5, 0.5).

Contrast diagram

Effect inputs and outputs are assumed to be in premultiplied alpha format, but this effect operates internally on straight alpha data, so its input values will be unpremultiplied, then the contrast adjustment applied, and finally the result converted back to premultiplied format.

This Windows Runtime type corresponds to the D2D Contrast effect.

See Also