The example Perform binary contrast enhancement on an image in C# performs binary contrast enhancement by setting each pixel to black or white depending on whether the sum of its red, green, and blue component values is greater than 3 * 128 = 384. For images that are particularly dark or light, however, the result may be too dark or too light.

This example lets you use a scroll bar to determine what cutoff value to use in performing the adjustment. In the picture, the cutoff value was fairly high so many of the mid-shade pixels in the original image were changed to black.

Whenever the program loads a new image or the user adjusts the scroll bar, the code calls the following PerformEnhancement method.

// Perform the binary contrast enhancement.
private void PerformEnhancement()
{
    // Perform contrast enhancement.
    Bitmap bm = new Bitmap(picOriginal.Image);
    BinaryContrast(bm, scrCutoff.Value);

    // Display the result.
    picOriginal.Visible = true;
    picResult.Image = bm;
    picResult.Left = picOriginal.Right + 4;
    picResult.Visible = true;
    this.ClientSize = new Size(
        picResult.Right + picOriginal.Left,
        picResult.Bottom + picOriginal.Left);
}

The code creates a new Bitmap that is a copy of the original image. It then calls the BinaryContrast method (see the earlier post for a description about that method) to perform the binary contrast enhancement, passing it the value selected by the scroll bar. It then displays the result.