void CLASS wavelet_denoise()
{
  float *fimg=0, *temp, thold, mul[2], avg, diff;
   int scale=1, size, lev, hpass, lpass, row, col, nc, c, i, wlast, blk[2];
  ushort *window[4];
  static const float noise[] =
  { 0.8002,0.2735,0.1202,0.0585,0.0291,0.0152,0.0080,0.0044 };

#ifdef DCRAW_VERBOSE
  if (verbose) fprintf (stderr,_("Wavelet denoising...\n"));
#endif

  while (maximum << scale < 0x10000) scale++;
  maximum <<= --scale;
  black <<= scale;
  FORC4 cblack[c] <<= scale;
  if ((size = iheight*iwidth) < 0x15550000)
    fimg = (float *) malloc ((size*3 + iheight + iwidth) * sizeof *fimg);
  merror (fimg, "wavelet_denoise()");
  temp = fimg + size*3;
  if ((nc = colors) == 3 && filters) nc++;
#ifdef LIBRAW_LIBRARY_BUILD
#pragma omp parallel default(shared) private(i,col,row,thold,lev,lpass,hpass,temp,c) firstprivate(scale,size) 
#endif
  {
      temp = (float*)malloc( (iheight + iwidth) * sizeof *fimg);
    FORC(nc) {			/* denoise R,G1,B,G3 individually */
#ifdef LIBRAW_LIBRARY_BUILD
#pragma omp for
#endif
      for (i=0; i < size; i++)
        fimg[i] = 256 * sqrt((double)(image[i][c] << scale));
      for (hpass=lev=0; lev < 5; lev++) {
	lpass = size*((lev & 1)+1);
#ifdef LIBRAW_LIBRARY_BUILD
#pragma omp for
#endif
	for (row=0; row < iheight; row++) {
	  hat_transform (temp, fimg+hpass+row*iwidth, 1, iwidth, 1 << lev);
	  for (col=0; col < iwidth; col++)
	    fimg[lpass + row*iwidth + col] = temp[col] * 0.25;
	}
#ifdef LIBRAW_LIBRARY_BUILD
#pragma omp for
#endif
	for (col=0; col < iwidth; col++) {
	  hat_transform (temp, fimg+lpass+col, iwidth, iheight, 1 << lev);
	  for (row=0; row < iheight; row++)
	    fimg[lpass + row*iwidth + col] = temp[row] * 0.25;
	}
	thold = threshold * noise[lev];
#ifdef LIBRAW_LIBRARY_BUILD
#pragma omp for
#endif
	for (i=0; i < size; i++) {
	  fimg[hpass+i] -= fimg[lpass+i];
	  if	(fimg[hpass+i] < -thold) fimg[hpass+i] += thold;
	  else if (fimg[hpass+i] >  thold) fimg[hpass+i] -= thold;
	  else	 fimg[hpass+i] = 0;
	  if (hpass) fimg[i] += fimg[hpass+i];
	}
	hpass = lpass;
      }
#ifdef LIBRAW_LIBRARY_BUILD
#pragma omp for
#endif
      for (i=0; i < size; i++)
	image[i][c] = CLIP(SQR(fimg[i]+fimg[lpass+i])/0x10000);
    }
    free(temp);
  } /* end omp parallel */
/* the following loops are hard to parallize, no idea yes,
 * problem is wlast which is carrying dependency
 * second part should be easyer, but did not yet get it right.
 */
  if (filters && colors == 3) {  /* pull G1 and G3 closer together */
   for (row=0; row < 2; row++){
      mul[row] = 0.125 * pre_mul[FC(row+1,0) | 1] / pre_mul[FC(row,0) | 1];
      blk[row] = cblack[FC(row,0) | 1];
   }
    for (i=0; i < 4; i++)
      window[i] = (ushort *) fimg + width*i;
    for (wlast=-1, row=1; row < height-1; row++) {
      while (wlast < row+1) {
	for (wlast++, i=0; i < 4; i++)
	  window[(i+3) & 3] = window[i];
	for (col = FC(wlast,1) & 1; col < width; col+=2)
	  window[2][col] = BAYER(wlast,col);
      }
      thold = threshold/512;
      for (col = (FC(row,0) & 1)+1; col < width-1; col+=2) {
	avg = ( window[0][col-1] + window[0][col+1] +
		window[2][col-1] + window[2][col+1] - blk[~row & 1]*4 )
	      * mul[row & 1] + (window[1][col] + blk[row & 1]) * 0.5;
	avg = avg < 0 ? 0 : sqrt(avg);
	diff = sqrt((double)BAYER(row,col)) - avg;
	if      (diff < -thold) diff += thold;
	else if (diff >  thold) diff -= thold;
	else diff = 0;
	BAYER(row,col) = CLIP(SQR(avg+diff) + 0.5);
      }
    }
  }
  free (fimg);
}