/*!
* bilateralCreate()
*
* Input: pixs (8 bpp gray, no colormap)
* spatial_stdev (of gaussian kernel; in pixels, > 0.5)
* range_stdev (of gaussian range kernel; > 5.0; typ. 50.0)
* ncomps (number of intermediate sums J(k,x); in [4 ... 30])
* reduction (1, 2 or 4)
* Return: bil, or null on error
*
* Notes:
* (1) This initializes a bilateral filtering operation, generating all
* the data required. It takes most of the time in the bilateral
* filtering operation.
* (2) See bilateral.h for details of the algorithm.
* (3) See pixBilateral() for constraints on input parameters, which
* are not checked here.
*/
static L_BILATERAL *
bilateralCreate(PIX *pixs,
l_float32 spatial_stdev,
l_float32 range_stdev,
l_int32 ncomps,
l_int32 reduction) {
l_int32 w, ws, wd, h, hs, hd, i, j, k, index;
l_int32 border, minval, maxval, spatial_size;
l_int32 halfwidth, wpls, wplt, wpld, kval, nval, dval;
l_float32 sstdev, fval1, fval2, denom, sum, norm, kern;
l_int32 *nc, *kindex;
l_float32 *kfract, *range, *spatial;
l_uint32 *datas, *datat, *datad, *lines, *linet, *lined;
L_BILATERAL *bil;
PIX *pixt, *pixt2, *pixsc, *pixd;
PIXA *pixac;
PROCNAME("bilateralCreate");
sstdev = spatial_stdev / (l_float32) reduction; /* reduced spat. stdev */
if ((bil = (L_BILATERAL *) CALLOC(1, sizeof(L_BILATERAL))) == NULL)
return (L_BILATERAL *) ERROR_PTR("bil not made", procName, NULL);
bil->spatial_stdev = sstdev;
bil->range_stdev = range_stdev;
bil->reduction = reduction;
bil->ncomps = ncomps;
if (reduction == 1) {
pixt = pixClone(pixs);
} else if (reduction == 2) {
pixt = pixScaleAreaMap2(pixs);
} else { /* reduction == 4) */
pixt2 = pixScaleAreaMap2(pixs);
pixt = pixScaleAreaMap2(pixt2);
pixDestroy(&pixt2);
}
pixGetExtremeValue(pixt, 1, L_SELECT_MIN, NULL, NULL, NULL, &minval);
pixGetExtremeValue(pixt, 1, L_SELECT_MAX, NULL, NULL, NULL, &maxval);
bil->minval = minval;
bil->maxval = maxval;
border = (l_int32)(2 * sstdev + 1);
pixsc = pixAddMirroredBorder(pixt, border, border, border, border);
bil->pixsc = pixsc;
pixDestroy(&pixt);
bil->pixs = pixClone(pixs);
/* -------------------------------------------------------------------- *
* Generate arrays for interpolation of J(k,x):
* (1.0 - kfract[.]) * J(kindex[.], x) + kfract[.] * J(kindex[.] + 1, x),
* where I(x) is the index into kfract[] and kindex[],
* and x is an index into the 2D image array.
* -------------------------------------------------------------------- */
/* nc is the set of k values to be used in J(k,x) */
nc = (l_int32 *) CALLOC(ncomps, sizeof(l_int32));
for (i = 0; i < ncomps; i++)
nc[i] = minval + i * (maxval - minval) / (ncomps - 1);
bil->nc = nc;
/* kindex maps from intensity I(x) to the lower k index for J(k,x) */
kindex = (l_int32 *) CALLOC(256, sizeof(l_int32));
for (i = minval, k = 0; i <= maxval && k < ncomps - 1; k++) {
fval2 = nc[k + 1];
while (i < fval2) {
kindex[i] = k;
i++;
}
}
kindex[maxval] = ncomps - 2;
bil->kindex = kindex;
/* kfract maps from intensity I(x) to the fraction of J(k+1,x) used */
kfract = (l_float32 *) CALLOC(256, sizeof(l_float32)); /* from lower */
for (i = minval, k = 0; i <= maxval && k < ncomps - 1; k++) {
fval1 = nc[k];
fval2 = nc[k + 1];
while (i < fval2) {
kfract[i] = (l_float32)(i - fval1) / (l_float32)(fval2 - fval1);
i++;
}
}
kfract[maxval] = 1.0;
bil->kfract = kfract;
#if DEBUG_BILATERAL
for (i = minval; i <= maxval; i++)
fprintf(stderr, "kindex[%d] = %d; kfract[%d] = %5.3f\n",
i, kindex[i], i, kfract[i]);
for (i = 0; i < ncomps; i++)
fprintf(stderr, "nc[%d] = %d\n", i, nc[i]);
#endif /* DEBUG_BILATERAL */
/* -------------------------------------------------------------------- *
* Generate 1-D kernel arrays (spatial and range) *
* -------------------------------------------------------------------- */
spatial_size = 2 * sstdev + 1;
spatial = (l_float32 *) CALLOC(spatial_size, sizeof(l_float32));
denom = 2. * sstdev * sstdev;
for (i = 0; i < spatial_size; i++)
spatial[i] = expf(-(l_float32)(i * i) / denom);
bil->spatial = spatial;
range = (l_float32 *) CALLOC(256, sizeof(l_float32));
denom = 2. * range_stdev * range_stdev;
for (i = 0; i < 256; i++)
range[i] = expf(-(l_float32)(i * i) / denom);
bil->range = range;
/* -------------------------------------------------------------------- *
* Generate principal bilateral component images *
* -------------------------------------------------------------------- */
pixac = pixaCreate(ncomps);
pixGetDimensions(pixsc, &ws, &hs, NULL);
datas = pixGetData(pixsc);
wpls = pixGetWpl(pixsc);
pixGetDimensions(pixs, &w, &h, NULL);
wd = (w + reduction - 1) / reduction;
hd = (h + reduction - 1) / reduction;
halfwidth = (l_int32)(2.0 * sstdev);
for (index = 0; index < ncomps; index++) {
pixt = pixCopy(NULL, pixsc);
datat = pixGetData(pixt);
wplt = pixGetWpl(pixt);
kval = nc[index];
/* Separable convolutions: horizontal first */
for (i = 0; i < hd; i++) {
lines = datas + (border + i) * wpls;
linet = datat + (border + i) * wplt;
for (j = 0; j < wd; j++) {
sum = 0.0;
norm = 0.0;
for (k = -halfwidth; k <= halfwidth; k++) {
nval = GET_DATA_BYTE(lines, border + j + k);
kern = spatial[L_ABS(k)] * range[L_ABS(kval - nval)];
sum += kern * nval;
norm += kern;
}
dval = (l_int32)((sum / norm) + 0.5);
SET_DATA_BYTE(linet, border + j, dval);
}
}
/* Vertical convolution */
pixd = pixCreate(wd, hd, 8);
datad = pixGetData(pixd);
wpld = pixGetWpl(pixd);
for (i = 0; i < hd; i++) {
linet = datat + (border + i) * wplt;
lined = datad + i * wpld;
for (j = 0; j < wd; j++) {
sum = 0.0;
norm = 0.0;
for (k = -halfwidth; k <= halfwidth; k++) {
nval = GET_DATA_BYTE(linet + k * wplt, border + j);
kern = spatial[L_ABS(k)] * range[L_ABS(kval - nval)];
sum += kern * nval;
norm += kern;
}
dval = (l_int32)((sum / norm) + 0.5);
SET_DATA_BYTE(lined, j, dval);
}
}
pixDestroy(&pixt);
pixaAddPix(pixac, pixd, L_INSERT);
}
bil->pixac = pixac;
bil->lineset = (l_uint32 ***) pixaGetLinePtrs(pixac, NULL);
return bil;
}
Pix* reduce2(Pix* pix){
return pixScaleAreaMap2(pix);
}
