void CLASS foveon_interpolate()
{
  static const short hood[] = { -1,-1, -1,0, -1,1, 0,-1, 0,1, 1,-1, 1,0, 1,1 };
  short *pix, prev[3], *curve[8], (*shrink)[3];
  float cfilt=0, ddft[3][3][2], ppm[3][3][3];
  float cam_xyz[3][3], correct[3][3], last[3][3], trans[3][3];
  float chroma_dq[3], color_dq[3], diag[3][3], div[3];
  float (*black)[3], (*sgain)[3], (*sgrow)[3];
  float fsum[3], val, frow, num;
  int row, col, c, i, j, diff, sgx, irow, sum, min, max, limit;
  int dscr[2][2], dstb[4], (*smrow[7])[3], total[4], ipix[3];
  int work[3][3], smlast, smred, smred_p=0, dev[3];
  int satlev[3], keep[4], active[4];
  unsigned dim[3], *badpix;
  double dsum=0, trsum[3];
  char str[128];
  const char* cp;

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

  foveon_load_camf();
  foveon_fixed (dscr, 4, "DarkShieldColRange");
  foveon_fixed (ppm[0][0], 27, "PostPolyMatrix");
  foveon_fixed (satlev, 3, "SaturationLevel");
  foveon_fixed (keep, 4, "KeepImageArea");
  foveon_fixed (active, 4, "ActiveImageArea");
  foveon_fixed (chroma_dq, 3, "ChromaDQ");
  foveon_fixed (color_dq, 3,
	foveon_camf_param ("IncludeBlocks", "ColorDQ") ?
		"ColorDQ" : "ColorDQCamRGB");
  if (foveon_camf_param ("IncludeBlocks", "ColumnFilter"))
		 foveon_fixed (&cfilt, 1, "ColumnFilter");

  memset (ddft, 0, sizeof ddft);
  if (!foveon_camf_param ("IncludeBlocks", "DarkDrift")
	 || !foveon_fixed (ddft[1][0], 12, "DarkDrift"))
    for (i=0; i < 2; i++) {
      foveon_fixed (dstb, 4, i ? "DarkShieldBottom":"DarkShieldTop");
      for (row = dstb[1]; row <= dstb[3]; row++)
	for (col = dstb[0]; col <= dstb[2]; col++)
	  FORC3 ddft[i+1][c][1] += (short) image[row*width+col][c];
      FORC3 ddft[i+1][c][1] /= (dstb[3]-dstb[1]+1) * (dstb[2]-dstb[0]+1);
    }

  if (!(cp = foveon_camf_param ("WhiteBalanceIlluminants", model2)))
  {
#ifdef DCRAW_VERBOSE
    fprintf (stderr,_("%s: Invalid white balance \"%s\"\n"), ifname, model2);
#endif
    return; }
  foveon_fixed (cam_xyz, 9, cp);
  foveon_fixed (correct, 9,
	foveon_camf_param ("WhiteBalanceCorrections", model2));
  memset (last, 0, sizeof last);
  for (i=0; i < 3; i++)
    for (j=0; j < 3; j++)
      FORC3 last[i][j] += correct[i][c] * cam_xyz[c][j];

  #define LAST(x,y) last[(i+x)%3][(c+y)%3]
  for (i=0; i < 3; i++)
    FORC3 diag[c][i] = LAST(1,1)*LAST(2,2) - LAST(1,2)*LAST(2,1);
  #undef LAST
  FORC3 div[c] = diag[c][0]*0.3127 + diag[c][1]*0.329 + diag[c][2]*0.3583;
  sprintf (str, "%sRGBNeutral", model2);
  if (foveon_camf_param ("IncludeBlocks", str))
    foveon_fixed (div, 3, str);
  num = 0;
  FORC3 if (num < div[c]) num = div[c];
  FORC3 div[c] /= num;

  memset (trans, 0, sizeof trans);
  for (i=0; i < 3; i++)
    for (j=0; j < 3; j++)
      FORC3 trans[i][j] += rgb_cam[i][c] * last[c][j] * div[j];
  FORC3 trsum[c] = trans[c][0] + trans[c][1] + trans[c][2];
  dsum = (6*trsum[0] + 11*trsum[1] + 3*trsum[2]) / 20;
  for (i=0; i < 3; i++)
    FORC3 last[i][c] = trans[i][c] * dsum / trsum[i];
  memset (trans, 0, sizeof trans);
  for (i=0; i < 3; i++)
    for (j=0; j < 3; j++)
      FORC3 trans[i][j] += (i==c ? 32 : -1) * last[c][j] / 30;

  foveon_make_curves (curve, color_dq, div, cfilt);
  FORC3 chroma_dq[c] /= 3;
  foveon_make_curves (curve+3, chroma_dq, div, cfilt);
  FORC3 dsum += chroma_dq[c] / div[c];
  curve[6] = foveon_make_curve (dsum, dsum, cfilt);
  curve[7] = foveon_make_curve (dsum*2, dsum*2, cfilt);

  sgain = (float (*)[3]) foveon_camf_matrix (dim, "SpatialGain");
  if (!sgain) return;
  sgrow = (float (*)[3]) calloc (dim[1], sizeof *sgrow);
  sgx = (width + dim[1]-2) / (dim[1]-1);

  black = (float (*)[3]) calloc (height, sizeof *black);
  for (row=0; row < height; row++) {
    for (i=0; i < 6; i++)
      ((float *)ddft[0])[i] = ((float *)ddft[1])[i] +
	row / (height-1.0) * (((float *)ddft[2])[i] - ((float *)ddft[1])[i]);
    FORC3 black[row][c] =
	( foveon_avg (image[row*width]+c, dscr[0], cfilt) +
	  foveon_avg (image[row*width]+c, dscr[1], cfilt) * 3
	  - ddft[0][c][0] ) / 4 - ddft[0][c][1];
  }
  memcpy (black, black+8, sizeof *black*8);
  memcpy (black+height-11, black+height-22, 11*sizeof *black);
  memcpy (last, black, sizeof last);

  for (row=1; row < height-1; row++) {
    FORC3 if (last[1][c] > last[0][c]) {
	if (last[1][c] > last[2][c])
	  black[row][c] = (last[0][c] > last[2][c]) ? last[0][c]:last[2][c];
      } else
	if (last[1][c] < last[2][c])
	  black[row][c] = (last[0][c] < last[2][c]) ? last[0][c]:last[2][c];
    memmove (last, last+1, 2*sizeof last[0]);
    memcpy (last[2], black[row+1], sizeof last[2]);
  }
  FORC3 black[row][c] = (last[0][c] + last[1][c])/2;
  FORC3 black[0][c] = (black[1][c] + black[3][c])/2;

  val = 1 - exp(-1/24.0);
  memcpy (fsum, black, sizeof fsum);
  for (row=1; row < height; row++)
    FORC3 fsum[c] += black[row][c] =
	(black[row][c] - black[row-1][c])*val + black[row-1][c];
  memcpy (last[0], black[height-1], sizeof last[0]);
  FORC3 fsum[c] /= height;
  for (row = height; row--; )
    FORC3 last[0][c] = black[row][c] =
	(black[row][c] - fsum[c] - last[0][c])*val + last[0][c];

  memset (total, 0, sizeof total);
  for (row=2; row < height; row+=4)
    for (col=2; col < width; col+=4) {
      FORC3 total[c] += (short) image[row*width+col][c];
      total[3]++;
    }
  for (row=0; row < height; row++)
    FORC3 black[row][c] += fsum[c]/2 + total[c]/(total[3]*100.0);

  for (row=0; row < height; row++) {
    for (i=0; i < 6; i++)
      ((float *)ddft[0])[i] = ((float *)ddft[1])[i] +
	row / (height-1.0) * (((float *)ddft[2])[i] - ((float *)ddft[1])[i]);
    pix = image[row*width];
    memcpy (prev, pix, sizeof prev);
    frow = row / (height-1.0) * (dim[2]-1);
    if ((irow = frow) == dim[2]-1) irow--;
    frow -= irow;
    for (i=0; i < dim[1]; i++)
      FORC3 sgrow[i][c] = sgain[ irow   *dim[1]+i][c] * (1-frow) +
			  sgain[(irow+1)*dim[1]+i][c] *    frow;
    for (col=0; col < width; col++) {
      FORC3 {
	diff = pix[c] - prev[c];
	prev[c] = pix[c];
	ipix[c] = pix[c] + floor ((diff + (diff*diff >> 14)) * cfilt
		- ddft[0][c][1] - ddft[0][c][0] * ((float) col/width - 0.5)
		- black[row][c] );
      }
      FORC3 {
	work[0][c] = ipix[c] * ipix[c] >> 14;
	work[2][c] = ipix[c] * work[0][c] >> 14;
	work[1][2-c] = ipix[(c+1) % 3] * ipix[(c+2) % 3] >> 14;
      }
      FORC3 {
	for (val=i=0; i < 3; i++)
	  for (  j=0; j < 3; j++)
	    val += ppm[c][i][j] * work[i][j];
	ipix[c] = floor ((ipix[c] + floor(val)) *
		( sgrow[col/sgx  ][c] * (sgx - col%sgx) +
		  sgrow[col/sgx+1][c] * (col%sgx) ) / sgx / div[c]);
	if (ipix[c] > 32000) ipix[c] = 32000;
	pix[c] = ipix[c];
      }
      pix += 4;
    }
  }
  free (black);
  free (sgrow);
  free (sgain);

  if ((badpix = (unsigned *) foveon_camf_matrix (dim, "BadPixels"))) {
    for (i=0; i < dim[0]; i++) {
      col = (badpix[i] >> 8 & 0xfff) - keep[0];
      row = (badpix[i] >> 20       ) - keep[1];
      if ((unsigned)(row-1) > height-3 || (unsigned)(col-1) > width-3)
	continue;
      memset (fsum, 0, sizeof fsum);
      for (sum=j=0; j < 8; j++)
	if (badpix[i] & (1 << j)) {
	  FORC3 fsum[c] += (short)
		image[(row+hood[j*2])*width+col+hood[j*2+1]][c];
	  sum++;
	}
      if (sum) FORC3 image[row*width+col][c] = fsum[c]/sum;
    }
    free (badpix);
  }

  /* Array for 5x5 Gaussian averaging of red values */
  smrow[6] = (int (*)[3]) calloc (width*5, sizeof **smrow);
  merror (smrow[6], "foveon_interpolate()");
  for (i=0; i < 5; i++)
    smrow[i] = smrow[6] + i*width;

  /* Sharpen the reds against these Gaussian averages */
  for (smlast=-1, row=2; row < height-2; row++) {
    while (smlast < row+2) {
      for (i=0; i < 6; i++)
	smrow[(i+5) % 6] = smrow[i];
      pix = image[++smlast*width+2];
      for (col=2; col < width-2; col++) {
	smrow[4][col][0] =
	  (pix[0]*6 + (pix[-4]+pix[4])*4 + pix[-8]+pix[8] + 8) >> 4;
	pix += 4;
      }
    }
    pix = image[row*width+2];
    for (col=2; col < width-2; col++) {
      smred = ( 6 *  smrow[2][col][0]
	      + 4 * (smrow[1][col][0] + smrow[3][col][0])
	      +      smrow[0][col][0] + smrow[4][col][0] + 8 ) >> 4;
      if (col == 2)
	smred_p = smred;
      i = pix[0] + ((pix[0] - ((smred*7 + smred_p) >> 3)) >> 3);
      if (i > 32000) i = 32000;
      pix[0] = i;
      smred_p = smred;
      pix += 4;
    }
  }

  /* Adjust the brighter pixels for better linearity */
  min = 0xffff;
  FORC3 {
    i = satlev[c] / div[c];
    if (min > i) min = i;
  }
  limit = min * 9 >> 4;
  for (pix=image[0]; pix < image[height*width]; pix+=4) {
    if (pix[0] <= limit || pix[1] <= limit || pix[2] <= limit)
      continue;
    min = max = pix[0];
    for (c=1; c < 3; c++) {
      if (min > pix[c]) min = pix[c];
      if (max < pix[c]) max = pix[c];
    }
    if (min >= limit*2) {
      pix[0] = pix[1] = pix[2] = max;
    } else {
      i = 0x4000 - ((min - limit) << 14) / limit;
      i = 0x4000 - (i*i >> 14);
      i = i*i >> 14;
      FORC3 pix[c] += (max - pix[c]) * i >> 14;
    }
  }
/*
   Because photons that miss one detector often hit another,
   the sum R+G+B is much less noisy than the individual colors.
   So smooth the hues without smoothing the total.
 */
  for (smlast=-1, row=2; row < height-2; row++) {
    while (smlast < row+2) {
      for (i=0; i < 6; i++)
	smrow[(i+5) % 6] = smrow[i];
      pix = image[++smlast*width+2];
      for (col=2; col < width-2; col++) {
	FORC3 smrow[4][col][c] = (pix[c-4]+2*pix[c]+pix[c+4]+2) >> 2;
	pix += 4;
      }
    }
    pix = image[row*width+2];
    for (col=2; col < width-2; col++) {
      FORC3 dev[c] = -foveon_apply_curve (curve[7], pix[c] -
	((smrow[1][col][c] + 2*smrow[2][col][c] + smrow[3][col][c]) >> 2));
      sum = (dev[0] + dev[1] + dev[2]) >> 3;
      FORC3 pix[c] += dev[c] - sum;
      pix += 4;
    }
  }
  for (smlast=-1, row=2; row < height-2; row++) {
    while (smlast < row+2) {
      for (i=0; i < 6; i++)
	smrow[(i+5) % 6] = smrow[i];
      pix = image[++smlast*width+2];
      for (col=2; col < width-2; col++) {
	FORC3 smrow[4][col][c] =
		(pix[c-8]+pix[c-4]+pix[c]+pix[c+4]+pix[c+8]+2) >> 2;
	pix += 4;
      }
    }
    pix = image[row*width+2];
    for (col=2; col < width-2; col++) {
      for (total[3]=375, sum=60, c=0; c < 3; c++) {
	for (total[c]=i=0; i < 5; i++)
	  total[c] += smrow[i][col][c];
	total[3] += total[c];
	sum += pix[c];
      }
      if (sum < 0) sum = 0;
      j = total[3] > 375 ? (sum << 16) / total[3] : sum * 174;
      FORC3 pix[c] += foveon_apply_curve (curve[6],
		((j*total[c] + 0x8000) >> 16) - pix[c]);
      pix += 4;
    }
  }

  /* Transform the image to a different colorspace */
  for (pix=image[0]; pix < image[height*width]; pix+=4) {
    FORC3 pix[c] -= foveon_apply_curve (curve[c], pix[c]);
    sum = (pix[0]+pix[1]+pix[1]+pix[2]) >> 2;
    FORC3 pix[c] -= foveon_apply_curve (curve[c], pix[c]-sum);
    FORC3 {
      for (dsum=i=0; i < 3; i++)
	dsum += trans[c][i] * pix[i];
      if (dsum < 0)  dsum = 0;
      if (dsum > 24000) dsum = 24000;
      ipix[c] = dsum + 0.5;
    }
    FORC3 pix[c] = ipix[c];
  }

  /* Smooth the image bottom-to-top and save at 1/4 scale */
  shrink = (short (*)[3]) calloc ((height/4), (width/4)*sizeof *shrink);
  merror (shrink, "foveon_interpolate()");
  for (row = height/4; row--; )
    for (col=0; col < width/4; col++) {
      ipix[0] = ipix[1] = ipix[2] = 0;
      for (i=0; i < 4; i++)
	for (j=0; j < 4; j++)
	  FORC3 ipix[c] += image[(row*4+i)*width+col*4+j][c];
      FORC3
	if (row+2 > height/4)
	  shrink[row*(width/4)+col][c] = ipix[c] >> 4;
	else
	  shrink[row*(width/4)+col][c] =
	    (shrink[(row+1)*(width/4)+col][c]*1840 + ipix[c]*141 + 2048) >> 12;
    }
  /* From the 1/4-scale image, smooth right-to-left */
  for (row=0; row < (height & ~3); row++) {
    ipix[0] = ipix[1] = ipix[2] = 0;
    if ((row & 3) == 0)
      for (col = width & ~3 ; col--; )
	FORC3 smrow[0][col][c] = ipix[c] =
	  (shrink[(row/4)*(width/4)+col/4][c]*1485 + ipix[c]*6707 + 4096) >> 13;

  /* Then smooth left-to-right */
    ipix[0] = ipix[1] = ipix[2] = 0;
    for (col=0; col < (width & ~3); col++)
      FORC3 smrow[1][col][c] = ipix[c] =
	(smrow[0][col][c]*1485 + ipix[c]*6707 + 4096) >> 13;

  /* Smooth top-to-bottom */
    if (row == 0)
      memcpy (smrow[2], smrow[1], sizeof **smrow * width);
    else
      for (col=0; col < (width & ~3); col++)
	FORC3 smrow[2][col][c] =
	  (smrow[2][col][c]*6707 + smrow[1][col][c]*1485 + 4096) >> 13;

  /* Adjust the chroma toward the smooth values */
    for (col=0; col < (width & ~3); col++) {
      for (i=j=30, c=0; c < 3; c++) {
	i += smrow[2][col][c];
	j += image[row*width+col][c];
      }
      j = (j << 16) / i;
      for (sum=c=0; c < 3; c++) {
	ipix[c] = foveon_apply_curve (curve[c+3],
	  ((smrow[2][col][c] * j + 0x8000) >> 16) - image[row*width+col][c]);
	sum += ipix[c];
      }
      sum >>= 3;
      FORC3 {
	i = image[row*width+col][c] + ipix[c] - sum;
	if (i < 0) i = 0;
	image[row*width+col][c] = i;
      }
    }
  }
  free (shrink);
  free (smrow[6]);
  for (i=0; i < 8; i++)
    free (curve[i]);

  /* Trim off the black border */
  active[1] -= keep[1];
  active[3] -= 2;
  i = active[2] - active[0];
  for (row=0; row < active[3]-active[1]; row++)
    memcpy (image[row*i], image[(row+active[1])*width+active[0]],
	 i * sizeof *image);
  width = i;
  height = row;
}