ColorMatrix Class

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.

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

System.Object
  System.Drawing.Imaging.ColorMatrix

public sealed class ColorMatrix

NameDescription
System_CAPS_pubmethodColorMatrix()

Initializes a new instance of the ColorMatrix class.

System_CAPS_pubmethodColorMatrix(Single[][])

Initializes a new instance of the ColorMatrix class using the elements in the specified matrix newColorMatrix.

NameDescription
System_CAPS_pubpropertyItem[Int32, Int32]

Gets or sets the element at the specified row and column in the ColorMatrix.

System_CAPS_pubpropertyMatrix00

Gets or sets the element at the 0 (zero) row and 0 column of this ColorMatrix.

System_CAPS_pubpropertyMatrix01

Gets or sets the element at the 0 (zero) row and first column of this ColorMatrix.

System_CAPS_pubpropertyMatrix02

Gets or sets the element at the 0 (zero) row and second column of this ColorMatrix.

System_CAPS_pubpropertyMatrix03

Gets or sets the element at the 0 (zero) row and third column of this ColorMatrix. Represents the alpha component.

System_CAPS_pubpropertyMatrix04

Gets or sets the element at the 0 (zero) row and fourth column of this ColorMatrix.

System_CAPS_pubpropertyMatrix10

Gets or sets the element at the first row and 0 (zero) column of this ColorMatrix.

System_CAPS_pubpropertyMatrix11

Gets or sets the element at the first row and first column of this ColorMatrix.

System_CAPS_pubpropertyMatrix12

Gets or sets the element at the first row and second column of this ColorMatrix.

System_CAPS_pubpropertyMatrix13

Gets or sets the element at the first row and third column of this ColorMatrix. Represents the alpha component.

System_CAPS_pubpropertyMatrix14

Gets or sets the element at the first row and fourth column of this ColorMatrix.

System_CAPS_pubpropertyMatrix20

Gets or sets the element at the second row and 0 (zero) column of this ColorMatrix.

System_CAPS_pubpropertyMatrix21

Gets or sets the element at the second row and first column of this ColorMatrix.

System_CAPS_pubpropertyMatrix22

Gets or sets the element at the second row and second column of this ColorMatrix.

System_CAPS_pubpropertyMatrix23

Gets or sets the element at the second row and third column of this ColorMatrix.

System_CAPS_pubpropertyMatrix24

Gets or sets the element at the second row and fourth column of this ColorMatrix.

System_CAPS_pubpropertyMatrix30

Gets or sets the element at the third row and 0 (zero) column of this ColorMatrix.

System_CAPS_pubpropertyMatrix31

Gets or sets the element at the third row and first column of this ColorMatrix.

System_CAPS_pubpropertyMatrix32

Gets or sets the element at the third row and second column of this ColorMatrix.

System_CAPS_pubpropertyMatrix33

Gets or sets the element at the third row and third column of this ColorMatrix. Represents the alpha component.

System_CAPS_pubpropertyMatrix34

Gets or sets the element at the third row and fourth column of this ColorMatrix.

System_CAPS_pubpropertyMatrix40

Gets or sets the element at the fourth row and 0 (zero) column of this ColorMatrix.

System_CAPS_pubpropertyMatrix41

Gets or sets the element at the fourth row and first column of this ColorMatrix.

System_CAPS_pubpropertyMatrix42

Gets or sets the element at the fourth row and second column of this ColorMatrix.

System_CAPS_pubpropertyMatrix43

Gets or sets the element at the fourth row and third column of this ColorMatrix. Represents the alpha component.

System_CAPS_pubpropertyMatrix44

Gets or sets the element at the fourth row and fourth column of this ColorMatrix.

NameDescription
System_CAPS_pubmethodEquals(Object)

Determines whether the specified object is equal to the current object.(Inherited from Object.)

System_CAPS_pubmethodGetHashCode()

Serves as the default hash function. (Inherited from Object.)

System_CAPS_pubmethodGetType()

Gets the Type of the current instance.(Inherited from Object.)

System_CAPS_pubmethodToString()

Returns a string that represents the current object.(Inherited from Object.)

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 .

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
Available since 1.1

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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