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();
}
while (v1 <= 0.00000000001);

v2 = r2.NextDouble();
temp = Math.Sqrt(-2 * Math.Log(v1)) * Math.Cos(2 * Math.PI * v2) * gnoise.GetSigma + gnoise.GetMean;
//temp = (1 / gnoise.GetSigma * Math.Sqrt(2 * Math.Sqrt(2 * Math.PI)) * Math.Pow(Math.E, - (Math.Pow(v1 - gnoise.GetMean, 2) / (2 * gnoise.GetSigma * gnoise.GetSigma))));
temp = temp + grayvalues[i];
if (temp > 255)
{
grayvalues[i] = 255;

}
else if (temp < 0)
{
grayvalues[i] = 0;
}
else
grayvalues[i] = Convert.ToByte(temp);
}
System.Runtime.InteropServices.Marshal.Copy(grayvalues, 0, ptr, bytes);
CurBitmap.UnlockBits(bmpData);
}
gnoise.Close();
Invalidate();
}

[解决办法]
int bytes = CurBitmap.Width * CurBitmap.Height;
长度不对，标准一个像素点包含RGB三个字节，所以应该是

int bytes = CurBitmap.Width * CurBitmap.Height*3;