C# Convert Image Grayscale

c#_convertImageGrayscale.cs

// source: https://stackoverflow.com/a/3054357/826308
public static Image ConvertToGrayscale(Image image)
{
    Image grayscaleImage = new Bitmap(image.Width, image.Height, image.PixelFormat);

    // Create the ImageAttributes object and apply the ColorMatrix
    ImageAttributes attributes = new System.Drawing.Imaging.ImageAttributes();
    ColorMatrix grayscaleMatrix = new ColorMatrix(new float[][]{
                                                    new float[] {0.299f, 0.299f, 0.299f, 0, 0},
                                                    new float[] {0.587f, 0.587f, 0.587f, 0, 0},
                                                    new float[] {0.114f, 0.114f, 0.114f, 0, 0},
                                                    new float[] {     0,      0,      0, 1, 0},
                                                    new float[] {     0,      0,      0, 0, 1}
                                                    });
    attributes.SetColorMatrix(grayscaleMatrix);

    // Use a new Graphics object from the new image.
    using (Graphics g = Graphics.FromImage(grayscaleImage))
    {
        // Draw the original image using the ImageAttributes created above.
        g.DrawImage(image,
                    new Rectangle(0, 0, grayscaleImage.Width, grayscaleImage.Height),
                    0, 0, grayscaleImage.Width, grayscaleImage.Height,
                    GraphicsUnit.Pixel,
                    attributes);
    }

    return grayscaleImage;
}