ImageAttributes.SetNoOp Method ()


The .NET API Reference documentation has a new home. Visit the .NET API Browser on to see the new experience.

Turns off color adjustment for the default category. You can call the ClearNoOp method to reinstate the color-adjustment settings that were in place before the call to the SetNoOp method.

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

public void SetNoOp()

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.

The following code example is designed for use with Windows Forms, and it requires PaintEventArgse, which is a parameter of the Paint event handler. The code performs the following actions:

  1. Opens an Image that uses the file Camera.jpg.

  2. Sets the gamma value of the ImageAttributes object to 0.25.

  3. Draws the image to the screen.

  4. Calls the SetNoOp method.

  5. Draws the image (a second camera) to the screen; however, because the SetNoOp method was called, the gamma setting defaults to a value of 1.0 and the image is drawn to the screen with the default gamma setting.

Note that the image on the left is very washed out (gamma of 0.25) and the image on the right has more contrast (gamma of 1.0).

private void SetNoOpExample(PaintEventArgs e)

    // Create an Image object from the file Camera.jpg.
    Image myImage = Image.FromFile("Camera.jpg");

    // Create an ImageAttributes object, and set the gamma to 0.25.
    ImageAttributes imageAttr = new ImageAttributes();

    // Draw the image with gamma set to 0.25.
    Rectangle rect1 = new Rectangle(20, 20, 200, 200);
    e.Graphics.DrawImage(myImage, rect1, 0, 0, 200, 200, 
        GraphicsUnit.Pixel, imageAttr);    

    // Call the ImageAttributes NoOp method.

    // Draw the image after NoOp is set, so the default gamma value
    // of 1.0 will be used.
    Rectangle rect2 = new Rectangle(250, 20, 200, 200);
    e.Graphics.DrawImage(myImage, rect2, 0, 0, 200, 200, 
        GraphicsUnit.Pixel, imageAttr);    

.NET Framework
Available since 1.1
Return to top