Gray Scale 2

using System.Drawing.Imaging;

public static Bitmap MakeGrayscale(Bitmap original)
{
    //create a blank bitmap the same size as original
    Bitmap newBitmap =
    new Bitmap(original.Width, original.Height);

    //get a graphics object from the new image
    Graphics g = Graphics.FromImage(newBitmap);

    //create the grayscale ColorMatrix
    ColorMatrix colorMatrix = new 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}});

    //create some image attributes
    ImageAttributes attributes = new ImageAttributes();

    //set the color matrix attribute
    attributes.SetColorMatrix(colorMatrix);

    //draw the original image on the new image
    //using the grayscale color matrix
    g.DrawImage(original,
    new Rectangle(0, 0, original.Width, original.Height),
    0, 0, original.Width, original.Height,
    GraphicsUnit.Pixel, attributes);

    //dispose the Graphics object
    g.Dispose();
    return newBitmap;
}

private void button1_Click(object sender, EventArgs e)
{
    Bitmap b = (Bitmap) pictureBox1.Image;
    pictureBox2.Image = MakeGrayscale(b);
}