Blend Class

Linear Gradient Blending filter.

Inheritance Hierarchy

SystemObject
Accord.Imaging.FiltersBaseTransformationFilter
Accord.Imaging.FiltersBlend

Namespace: Accord.Imaging.Filters
Assembly: Accord.Imaging (in Accord.Imaging.dll) Version: 3.8.0

Syntax

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public class Blend : BaseTransformationFilter

Public Class Blend
	Inherits BaseTransformationFilter

Request Example View Source

The Blend type exposes the following members.

Constructors

	Name	Description
	Blend(Bitmap)	Constructs a new Blend filter.
	Blend(Double, Bitmap)	Constructs a new Blend filter.
	Blend(MatrixH, Bitmap)	Constructs a new Blend filter.

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Properties

	Name	Description
	AlphaOnly	Gets or sets a value indicating whether only the alpha channel should be blended. This can be used together with a transparency mask to selectively blend only portions of the image.
	FillColor	Gets or sets the filling color used to fill blank spaces.
	FormatTranslations	Format translations dictionary. (Overrides BaseTransformationFilterFormatTranslations.)
	Gradient	Gets or sets a value indicating whether to blend using a linear gradient or just superimpose the two images with equal weights.
	Homography	Gets or sets the Homography matrix used to map a image passed to the filter to the overlay image specified at filter creation.

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Methods

	Name	Description
	Apply(Bitmap)	Apply filter to an image. (Inherited from BaseTransformationFilter.)
	Apply(BitmapData)	Apply filter to an image. (Inherited from BaseTransformationFilter.)
	Apply(UnmanagedImage)	Apply filter to an image in unmanaged memory. (Inherited from BaseTransformationFilter.)
	Apply(UnmanagedImage, UnmanagedImage)	Apply filter to an image in unmanaged memory. (Inherited from BaseTransformationFilter.)
	CalculateNewImageSize	Computes the new image size. (Overrides BaseTransformationFilterCalculateNewImageSize(UnmanagedImage).)
	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 image filter. (Overrides BaseTransformationFilterProcessFilter(UnmanagedImage, UnmanagedImage).)
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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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.)

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Remarks

The blending filter is able to blend two images using a homography matrix. A linear alpha gradient is used to smooth out differences between the two images, effectively blending them in two images. The gradient is computed considering the distance between the centers of the two images.

The first image should be passed at the moment of creation of the Blending filter as the overlay image. A second image may be projected on top of the overlay image by calling the Apply method and passing the second image as argument.

Currently the filter always produces 32bpp images, disregarding the format of source images. The alpha layer is used as an intermediate mask in the blending process.

Examples

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// Let's start with two pictures that have been
// taken from slightly different points of view:
// 
Bitmap img1 = Resources.dc_left;
Bitmap img2 = Resources.dc_right;

// Those pictures are shown below:
ImageBox.Show(img1, PictureBoxSizeMode.Zoom, 640, 480);
ImageBox.Show(img2, PictureBoxSizeMode.Zoom, 640, 480);

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// Step 1: Detect feature points using Surf Corners Detector
var surf = new SpeededUpRobustFeaturesDetector();

var points1 = surf.ProcessImage(img1);
var points2 = surf.ProcessImage(img2);

// Step 2: Match feature points using a k-NN
var matcher = new KNearestNeighborMatching(5);
var matches = matcher.Match(points1, points2);

// Step 3: Create the matrix using a robust estimator
var ransac = new RansacHomographyEstimator(0.001, 0.99);
MatrixH homographyMatrix = ransac.Estimate(matches);

// Step 4: Project and blend using the homography
Blend blend = new Blend(homographyMatrix, img1);


// Compute the blending algorithm
Bitmap result = blend.Apply(img2);

// Show on screen
ImageBox.Show(result, PictureBoxSizeMode.Zoom, 640, 480);

The resulting image is shown below.

Reference

Accord.Imaging.Filters Namespace