ImageAttributes.SetGamma Method (Single)


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Sets the gamma value for the default category.

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

public void SetGamma(
	float gamma


Type: System.Single

The gamma correction value.

Typical values for the gamma parameter are from 1.0 to 2.2; however, values from 0.1 to 5.0 could prove useful in some circumstances.

An ImageAttributes object maintains color and grayscale settings for five adjustment categories: default, bitmap, brush, pen, and text. For example, you can specify a gamma value for the default category, a different gamma value for the bitmap category, and still a different gamma value for the pen category.

The default color-adjustment and grayscale-adjustment settings apply to all categories that do not have adjustment settings of their own. For example, if you never specify any adjustment settings for the pen category, the default settings apply to the pen category.

Gamma values outside the usual range may be useful for old CRT monitors or for monitors that are in unusual lighting conditions, such as industrial environments or window displays.

The following code example is designed for use with Windows Forms, and it requires PaintEventArgse, which is a parameter of the Paint event handler. In addition, you need to change the image file path to a path and image name valid on your system. The code performs the following actions:

  1. Opens an Image that uses the file Camera.jpg and draws it to the screen using the default value for gamma.

  2. Creates an ImageAttributes object and sets its gamma to 2.2 by calling the SetGamma method.

  3. Draws the image (a second camera) to the screen using the gamma value just set in the ImageAttributes object.

private void SetGammaExample(PaintEventArgs e)

    // Create an Image object from the file Camera.jpg, and draw it to
    // the screen.
    Image myImage = Image.FromFile("Camera.jpg");
    e.Graphics.DrawImage(myImage, 20, 20);

    // Create an ImageAttributes object and set the gamma to 2.2.
    System.Drawing.Imaging.ImageAttributes imageAttr = 
           new System.Drawing.Imaging.ImageAttributes();

    // Draw the image with gamma set to 2.2.
    Rectangle rect = new Rectangle(250, 20, 200, 200);
    e.Graphics.DrawImage(myImage, rect, 0, 0, 200, 200, 
        GraphicsUnit.Pixel, imageAttr);    

.NET Framework
Available since 1.1
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