小日本的图片处理C#类

    本来想写一个将图片处理成磨砂玻璃的函数，从网上找到一个C#的类，小日本的代码,功能较多，没有注释。处理出来的效果还可以，但不是我想要的
ImageUtils.cs

用这个类写的“磨砂玻璃”效果如下：

代码：

        public static bool FrostedGlass(ref Bitmap bmp, Rectangle rect,
            int alphaPercent, int blurZone)
        {
            if (bmp.PixelFormat != PixelFormat.Format24bppRgb)
                return false;

            int w = bmp.Width;
            int h = bmp.Height;

            Bitmap tmp = new Bitmap(rect.Width, rect.Height,
                                         PixelFormat.Format24bppRgb);
            Graphics g = Graphics.FromImage(tmp);
            g.DrawImage(bmp, 0, 0, rect, GraphicsUnit.Pixel);
            g.Dispose();

            ImgUtils.GaussianBlur(ref tmp, blurZone);

            Bitmap tmp2 = tmp.Clone() as Bitmap;
            g = Graphics.FromImage(tmp2);
            g.Clear(Color.FromArgb(244, 244, 244));
            ImgUtils.JAlphaBlend(g, tmp, (float)alphaPercent / 100f, 0, 0);
            g.Dispose();

            tmp.Dispose();

            g = Graphics.FromImage(bmp);
            g.DrawImageUnscaled(tmp2, rect.Left, rect.Top);
            g.Dispose();

            tmp2.Dispose();

            return true;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Bitmap bmp = new Bitmap(@"C:¥Home¥img2¥reika1.png");

            Graphics g = this.CreateGraphics();
            //g.DrawImageUnscaled(bmp, 5, 5);

            if (FrostedGlass(ref bmp, new Rectangle(88, 50, 219, 550), 50, 3))
            {
                g.DrawImageUnscaled(bmp, 5, 5);
                Clipboard.SetImage(bmp);
            }

            g.Dispose();
            bmp.Dispose();
        }