mouse curser movement to change color

private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
    {
    Bitmap b = (Bitmap) pictureBox1.Image;
    Color c = b.GetPixel(e.X, e.Y);
    c = Color.FromArgb(c.ToArgb() ^ 0xffffff);
    b.SetPixel( e.X, e.Y, c);
    pictureBox1.Invalidate();
    }