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ColorMatrix Class

Defines a 5 x 5 matrix that contains the coordinates for the RGBAW space. Several methods of the ImageAttributes class adjust image colors by using a color matrix. This class cannot be inherited.

System.Object
  System.Drawing.Imaging.ColorMatrix

Namespace:  System.Drawing.Imaging
Assembly:  System.Drawing (in System.Drawing.dll)

public sealed class ColorMatrix

The ColorMatrix type exposes the following members.

  NameDescription
Public methodColorMatrix()Initializes a new instance of the ColorMatrix class.
Public methodColorMatrix(Single[][])Initializes a new instance of the ColorMatrix class using the elements in the specified matrix newColorMatrix.
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  NameDescription
Public propertyItemGets or sets the element at the specified row and column in the ColorMatrix.
Public propertyMatrix00Gets or sets the element at the 0 (zero) row and 0 column of this ColorMatrix.
Public propertyMatrix01Gets or sets the element at the 0 (zero) row and first column of this ColorMatrix.
Public propertyMatrix02Gets or sets the element at the 0 (zero) row and second column of this ColorMatrix.
Public propertyMatrix03Gets or sets the element at the 0 (zero) row and third column of this ColorMatrix. Represents the alpha component.
Public propertyMatrix04Gets or sets the element at the 0 (zero) row and fourth column of this ColorMatrix.
Public propertyMatrix10Gets or sets the element at the first row and 0 (zero) column of this ColorMatrix.
Public propertyMatrix11Gets or sets the element at the first row and first column of this ColorMatrix.
Public propertyMatrix12Gets or sets the element at the first row and second column of this ColorMatrix.
Public propertyMatrix13Gets or sets the element at the first row and third column of this ColorMatrix. Represents the alpha component.
Public propertyMatrix14Gets or sets the element at the first row and fourth column of this ColorMatrix.
Public propertyMatrix20Gets or sets the element at the second row and 0 (zero) column of this ColorMatrix.
Public propertyMatrix21Gets or sets the element at the second row and first column of this ColorMatrix.
Public propertyMatrix22Gets or sets the element at the second row and second column of this ColorMatrix.
Public propertyMatrix23Gets or sets the element at the second row and third column of this ColorMatrix.
Public propertyMatrix24Gets or sets the element at the second row and fourth column of this ColorMatrix.
Public propertyMatrix30Gets or sets the element at the third row and 0 (zero) column of this ColorMatrix.
Public propertyMatrix31Gets or sets the element at the third row and first column of this ColorMatrix.
Public propertyMatrix32Gets or sets the element at the third row and second column of this ColorMatrix.
Public propertyMatrix33Gets or sets the element at the third row and third column of this ColorMatrix. Represents the alpha component.
Public propertyMatrix34Gets or sets the element at the third row and fourth column of this ColorMatrix.
Public propertyMatrix40Gets or sets the element at the fourth row and 0 (zero) column of this ColorMatrix.
Public propertyMatrix41Gets or sets the element at the fourth row and first column of this ColorMatrix.
Public propertyMatrix42Gets or sets the element at the fourth row and second column of this ColorMatrix.
Public propertyMatrix43Gets or sets the element at the fourth row and third column of this ColorMatrix. Represents the alpha component.
Public propertyMatrix44Gets or sets the element at the fourth row and fourth column of this ColorMatrix.
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  NameDescription
Public methodEquals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Public methodGetHashCodeServes as the default hash function. (Inherited from Object.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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The matrix coefficients constitute a 5 x 5 linear transformation that is used for transforming ARGB homogeneous values. For example, an ARGB vector is represented as red, green, blue, alpha and w, where w is always 1.

For example, suppose you want to start with the color (0.2, 0.0, 0.4, 1.0) and apply the following transformations:

  1. Double the red component

  2. Add 0.2 to the red, green, and blue components

The following matrix multiplication will perform the pair of transformations in the order listed.

Recoloring

The elements of a color matrix are indexed (zero-based) by row and then column. For example, the entry in the fifth row and third column of matrix M is denoted by M[4][2].

The 5×5 identity matrix (shown in the following illustration) has 1s on the diagonal and 0s everywhere else. If you multiply a color vector by the identity matrix, the color vector does not change. A convenient way to form the matrix of a color transformation is to start with the identity matrix and make a small change that produces the desired transformation.

Recoloring

For a more detailed discussion of matrices and transformations, see Coordinate Systems and Transformations.

The following example takes an image that is all one color (0.2, 0.0, 0.4, 1.0) and applies the transformation described in the preceding paragraphs.

The following illustration shows the original image on the left and the transformed image on the right.

Colors

The code in the following example uses the following steps to perform the recoloring:

  1. Initialize a ColorMatrix object.

  2. Create an ImageAttributes object and pass the ColorMatrix object to the SetColorMatrix method of the ImageAttributes object.

  3. Pass the ImageAttributes object to the DrawImage method of a Graphics object.

The preceding example is designed for use with Windows Forms, and it requires PaintEventArgs e, which is a parameter of the Paint event handler

Image image = new Bitmap("InputColor.bmp");
ImageAttributes imageAttributes = new ImageAttributes();
int width = image.Width;
int height = image.Height;

float[][] colorMatrixElements = { 
   new float[] {2,  0,  0,  0, 0},        // red scaling factor of 2 
   new float[] {0,  1,  0,  0, 0},        // green scaling factor of 1 
   new float[] {0,  0,  1,  0, 0},        // blue scaling factor of 1 
   new float[] {0,  0,  0,  1, 0},        // alpha scaling factor of 1 
   new float[] {.2f, .2f, .2f, 0, 1}};    // three translations of 0.2

ColorMatrix colorMatrix = new ColorMatrix(colorMatrixElements);

imageAttributes.SetColorMatrix(
   colorMatrix,
   ColorMatrixFlag.Default,
   ColorAdjustType.Bitmap);

e.Graphics.DrawImage(image, 10, 10);

e.Graphics.DrawImage(
   image,
   new Rectangle(120, 10, width, height),  // destination rectangle 
   0, 0,        // upper-left corner of source rectangle 
   width,       // width of source rectangle
   height,      // height of source rectangle
   GraphicsUnit.Pixel,
   imageAttributes);

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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