Grayscale an image (in other words make it black and white)

grayscale.cs

/// <summary>
/// Grayscales an image
/// </summary>
/// <param name="source">Source image to grayscale</param>
/// <returns>New grayscaled image</returns>
private Image grayScale(ref Image source) {

    Bitmap bitMap = new Bitmap(source);

    using (Graphics g = Graphics.FromImage(bitMap)) {
        System.Drawing.Imaging.ColorMatrix matrix = new System.Drawing.Imaging.ColorMatrix(
              new float[][]
              {
                 new float[] {.3f, .3f, .3f, 0, 0},
                 new float[] {.59f, .59f, .59f, 0, 0},
                 new float[] {.11f, .11f, .11f, 0, 0},
                 new float[] {0, 0, 0, 1, 0},
                 new float[] {0, 0, 0, 0, 1}
              });

        System.Drawing.Imaging.ImageAttributes attributes = new System.Drawing.Imaging.ImageAttributes();
        attributes.SetColorMatrix(matrix);

        g.DrawImage(source, new Rectangle(0, 0, source.Width, source.Height), 0, 0, source.Width, source.Height, GraphicsUnit.Pixel, attributes);
    }

    return (Image)bitMap;
}