Method of edge detection (smoothed) in C# image processing

//Define the edge detection function of smoothed operatorprivate static Bitmap smoothed(Bitmap a)
{
 int w = ;
 int h = ;
 try
 {
  Bitmap dstBitmap = new Bitmap(w, h, .Format24bppRgb);
   srcData = (new Rectangle
   (0, 0, w, h), , .Format24bppRgb);
   dstData = (new Rectangle
   (0, 0, w, h), , .Format24bppRgb);
  unsafe
  {
   byte* pIn = (byte*)srcData.();
   byte* pOut = (byte*)dstData.();
   byte* p;
   int stride = ;
   for (int y = 0; y < h; y++)
   {
   for (int x = 0; x < w; x++)
   {
    //The pixels at the edge of the eight points remain unchanged    if (x == 0 || x == w - 1 || y == 0 || y == h - 1)
    {
    pOut[0] = pIn[0];
    pOut[1] = pIn[1];
    pOut[2] = pIn[2];
     }
    else
    {
    int r0, r1, r2, r3, r4, r5, r6, r7, r8;
    int g1, g2, g3, g4, g5, g6, g7, g8, g0;
    int b1, b2, b3, b4, b5, b6, b7, b8, b0;
    double vR, vG, vB;
    //On top left    p = pIn - stride - 3;
    r1 = p[2];
    g1 = p[1];
    b1 = p[0];
    //Previously    p = pIn - stride;
    r2 = p[2];
    g2 = p[1];
    b2 = p[0];
    //Up to the right    p = pIn - stride + 3;
    r3 = p[2];
    g3 = p[1];
    b3 = p[0];
    //Left    p = pIn - 3;
    r4 = p[2];
    g4 = p[1];
    b4 = p[0];
    //right    p = pIn + 3;
    r5 = p[2];
    g5 = p[1];
    b5 = p[0];
    //Lower left    p = pIn + stride - 3;
    r6 = p[2];
    g6 = p[1];
    b6 = p[0];
    //Online    p = pIn + stride;
    r7 = p[2];
    g7 = p[1];
    b7 = p[0];
    // Lower right    p = pIn + stride + 3;
    r8 = p[2];
    g8 = p[1];
    b8 = p[0];
    //Central point    p = pIn;
    r0 = p[2];
    g0 = p[1];
    b0 = p[0];
    //Use template    vR = (double)((r3+r5+r8-r1-r4-r6) + Math .Abs (r1+r2+r3-r6-r7-r8));
    vG = (double)((g3+g5+g8-g1-g4-g6) + Math .Abs (g1+g2+g3-g6-g7-g8));
    vB = (double)((b3+b5+b8-b1-b4-b6) + Math. Abs (b1+b2+b3-b6-b7-b8));
    if (vR > 0)
    {
     vR = (255, vR);
    }
    else
    {
     vR = (0, vR);
    }
     if (vG > 0)
    {
     vG = (255, vG);
    }
    else
    {
     vG = (0, vG);
    }
     if (vB > 0)
    {
     vB = (255, vB);
    }
    else
    {
     vB = (0, vB);
    }
    pOut[0] = (byte)vB;
    pOut[1] = (byte)vG;
    pOut[2] = (byte)vR;
     }
    pIn += 3;
    pOut += 3;
   }
   pIn +=  - w * 3;
   pOut +=  - w * 3;
    }
  }
  (srcData);
  (dstData);
   return dstBitmap;
 }
 catch
 {
  return null;
 }
}