docs: private void thresholdBlur(Kernel kernel, int[] inPixels, int[] outPixels, int width, int height, boolean alpha) {
  		int index = 0;
  		float[] matrix = kernel.getKernelData( null );
  		int cols = kernel.getWidth();
  		int cols2 = cols/2;
  
  		for (int y = 0; y < height; y++) {
  			int ioffset = y*width;
              int outIndex = y;
  			for (int x = 0; x < width; x++) {
  				float r = 0, g = 0, b = 0, a = 0;
  				int moffset = cols2;
  
                  int rgb1 = inPixels[ioffset+x];
                  int a1 = (rgb1 >> 24) & 0xff;
                  int r1 = (rgb1 >> 16) & 0xff;
                  int g1 = (rgb1 >> 8) & 0xff;
                  int b1 = rgb1 & 0xff;
  				float af = 0, rf = 0, gf = 0, bf = 0;
                  for (int col = -cols2; col <= cols2; col++) {
  					float f = matrix[moffset+col];
  
  					if (f != 0) {
  						int ix = x+col;
  						if (!(0 <= ix && ix < width))
  							ix = x;
  						int rgb2 = inPixels[ioffset+ix];
                          int a2 = (rgb2 >> 24) & 0xff;
                          int r2 = (rgb2 >> 16) & 0xff;
                          int g2 = (rgb2 >> 8) & 0xff;
                          int b2 = rgb2 & 0xff;
  
  						int d;
                          d = a1-a2;
                          if ( d >= -threshold && d <= threshold ) {
                              a += f * a2;
                              af += f;
                          }
                          d = r1-r2;
                          if ( d >= -threshold && d <= threshold ) {
                              r += f * r2;
                              rf += f;
                          }
                          d = g1-g2;
                          if ( d >= -threshold && d <= threshold ) {
                              g += f * g2;
                              gf += f;
                          }
                          d = b1-b2;
                          if ( d >= -threshold && d <= threshold ) {
                              b += f * b2;
                              bf += f;
                          }
  					}
  				}
                  a = af == 0 ? a1 : a/af;
                  r = rf == 0 ? r1 : r/rf;
                  g = gf == 0 ? g1 : g/gf;
                  b = bf == 0 ? b1 : b/bf;
  				int ia = alpha ? PixelUtils.clamp((int)(a+0.5)) : 0xff;
  				int ir = PixelUtils.clamp((int)(r+0.5));
  				int ig = PixelUtils.clamp((int)(g+0.5));
  				int ib = PixelUtils.clamp((int)(b+0.5));
  				outPixels[outIndex] = (ia << 24) | (ir << 16) | (ig << 8) | ib;
                  outIndex += height;
  			}
  		}
  	}