图片添加高斯噪声
 这是添加高斯噪声的代码，有没有大神看看为什么这个代码只能给部分图像加噪声
private void btngauss_Click(object sender, EventArgs e)
        {
            if (CurBitmap != null)
            {
                gaussnoise gnoise = new gaussnoise();
                if (gnoise.ShowDialog() == DialogResult.OK)
                {

                    Rectangle rect = new Rectangle(0, 0, CurBitmap.Width, CurBitmap.Height);
                    System.Drawing.Imaging.BitmapData bmpData = CurBitmap.LockBits(rect, System.Drawing.Imaging.ImageLockMode.ReadWrite, CurBitmap.PixelFormat);
                    IntPtr ptr = bmpData.Scan0;
                    int bytes = CurBitmap.Width * CurBitmap.Height;
                    byte[] grayvalues = new byte[bytes];
                    System.Runtime.InteropServices.Marshal.Copy(ptr, grayvalues, 0, bytes);
                    double temp = 0;
                    Random r1, r2;
                    double v1, v2;
                    r1 = new Random(unchecked((int)DateTime.Now.Ticks));
                    r2 = new Random(unchecked((int)DateTime.Now.Ticks));
                    for (int i = 0; i < bytes; i++)
                    {
                        do
                        {
                            v1 = r1.NextDouble();
                    &