FastBoxBlur

fastBoxBlur.cs

private Bitmap FastBoxBlur(Bitmap img, int radius) {

 int kSize = radius; 

 if (kSize % 2 == 0) kSize++;
 Bitmap Hblur = img.Clone();

 float Avg = (float) 1 / kSize;

 for (int j = 0; j < img.Height(); j++) {

  float[] hSum = new float[] {
   0 f, 0 f, 0 f, 0 f
  };

  float[] iAvg = new float[] {
   0 f, 0 f, 0 f, 0 f
  };
    
  for (int x = 0; x < kSize; x++) {
   Color tmpColor = img.GetPixel(x, j);
   hSum[0] += tmpColor.A;
   hSum[1] += tmpColor.R;
   hSum[2] += tmpColor.G;
   hSum[3] += tmpColor.B;
  }
  iAvg[0] = hSum[0] * Avg;
  iAvg[1] = hSum[1] * Avg;
  iAvg[2] = hSum[2] * Avg;
  iAvg[3] = hSum[3] * Avg;
  for (int i = 0; i < img.Width(); i++) {
   if (i– kSize / 2 >= 0 && i + 1 + kSize / 2 < img.Width()) {
    Color tmp_pColor = img.GetPixel(i– kSize / 2, j);
    hSum[0] -= tmp_pColor.A;
    hSum[1] -= tmp_pColor.R;
    hSum[2] -= tmp_pColor.G;
    hSum[3] -= tmp_pColor.B;
    Color tmp_nColor = img.GetPixel(i + 1 + kSize / 2, j);
    hSum[0] += tmp_nColor.A;
    hSum[1] += tmp_nColor.R;
    hSum[2] += tmp_nColor.G;
    hSum[3] += tmp_nColor.B;
    //
    iAvg[0] = hSum[0] * Avg;
    iAvg[1] = hSum[1] * Avg;
    iAvg[2] = hSum[2] * Avg;
    iAvg[3] = hSum[3] * Avg;
   }
   Hblur.SetPixel(i, j, Color.FromArgb((int) iAvg[0], (int) iAvg[1], (int) iAvg[2], (int) iAvg[3]));
  }
 }
 Bitmap total = Hblur.Clone();
 for (int i = 0; i < Hblur.Width(); i++) {
  float[] tSum = new float[] {
   0 f, 0 f, 0 f, 0 f
  };
  float[] iAvg = new float[] {
   0 f, 0 f, 0 f, 0 f
  };
  for (int y = 0; y < kSize; y++) {
   Color tmpColor = Hblur.GetPixel(i, y);
   tSum[0] += tmpColor.A;
   tSum[1] += tmpColor.R;
   tSum[2] += tmpColor.G;
   tSum[3] += tmpColor.B;
  }
  iAvg[0] = tSum[0] * Avg;
  iAvg[1] = tSum[1] * Avg;
  iAvg[2] = tSum[2] * Avg;
  iAvg[3] = tSum[3] * Avg;

  for (int j = 0; j < Hblur.Height(); j++) {
   if (j– kSize / 2 >= 0 && j + 1 + kSize / 2 < Hblur.Height()) {
    Color tmp_pColor = Hblur.GetPixel(i, j– kSize / 2);
    tSum[0] -= tmp_pColor.A;
    tSum[1] -= tmp_pColor.R;
    tSum[2] -= tmp_pColor.G;
    tSum[3] -= tmp_pColor.B;
    Color tmp_nColor = Hblur.GetPixel(i, j + 1 + kSize / 2);
    tSum[0] += tmp_nColor.A;
    tSum[1] += tmp_nColor.R;
    tSum[2] += tmp_nColor.G;
    tSum[3] += tmp_nColor.B;
    //
    iAvg[0] = tSum[0] * Avg;
    iAvg[1] = tSum[1] * Avg;
    iAvg[2] = tSum[2] * Avg;
    iAvg[3] = tSum[3] * Avg;
   }
   total.SetPixel(i, j, Color.FromArgb((int) iAvg[0], (int) iAvg[1], (int) iAvg[2], (int) iAvg[3]));
  }
 }
 return total;
}