/*!
* dewarpBuildModel()
*
* Input: dew
* debugflag (1 for debugging output)
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) This is the basic function that builds the vertical
* disparity array, which allows determination of the
* src pixel in the input image corresponding to each
* dest pixel in the dewarped image.
* (2) The method is as follows:
* * Estimate the centers of all the long textlines and
* fit a LS quadratic to each one. This smooths the curves.
* * Sample each curve at a regular interval, find the y-value
* of the flat point on each curve, and subtract the sampled
* curve value from this value. This is the vertical
* disparity.
* * Fit a LS quadratic to each set of vertically aligned
* disparity samples. This smooths the disparity values
* in the vertical direction. Then resample at the same
* regular interval, We now have a regular grid of smoothed
* vertical disparity valuels.
* * Interpolate this grid to get a full resolution disparity
* map. This can be applied directly to the src image
* pixels to dewarp the image in the vertical direction,
* making all textlines horizontal.
*/
l_int32
dewarpBuildModel(L_DEWARP *dew,
l_int32 debugflag)
{
char *tempname;
l_int32 i, j, nlines, nx, ny, sampling;
l_float32 c0, c1, c2, x, y, flaty, val;
l_float32 *faflats;
NUMA *nax, *nafit, *nacurve, *nacurves, *naflat, *naflats, *naflatsi;
PIX *pixs, *pixt1, *pixt2;
PTA *pta, *ptad;
PTAA *ptaa1, *ptaa2, *ptaa3, *ptaa4, *ptaa5, *ptaa6, *ptaa7;
FPIX *fpix1, *fpix2, *fpix3;
PROCNAME("dewarpBuildModel");
if (!dew)
return ERROR_INT("dew not defined", procName, 1);
pixs = dew->pixs;
if (debugflag) {
pixDisplayWithTitle(pixs, 0, 0, "pixs", 1);
pixWriteTempfile("/tmp", "pixs.png", pixs, IFF_PNG, NULL);
}
/* Make initial estimate of centers of textlines */
ptaa1 = pixGetTextlineCenters(pixs, DEBUG_TEXTLINE_CENTERS);
if (debugflag) {
pixt1 = pixConvertTo32(pixs);
pixt2 = pixDisplayPtaa(pixt1, ptaa1);
pixWriteTempfile("/tmp", "lines1.png", pixt2, IFF_PNG, NULL);
pixDestroy(&pixt1);
pixDestroy(&pixt2);
}
/* Remove all lines that are not near the length
* of the longest line. */
ptaa2 = ptaaRemoveShortLines(pixs, ptaa1, 0.8, DEBUG_SHORT_LINES);
if (debugflag) {
pixt1 = pixConvertTo32(pixs);
pixt2 = pixDisplayPtaa(pixt1, ptaa2);
pixWriteTempfile("/tmp", "lines2.png", pixt2, IFF_PNG, NULL);
pixDestroy(&pixt1);
pixDestroy(&pixt2);
}
nlines = ptaaGetCount(ptaa2);
if (nlines < dew->minlines)
return ERROR_INT("insufficient lines to build model", procName, 1);
/* Do quadratic fit to smooth each line. A single quadratic
* over the entire width of the line appears to be sufficient.
* Quartics tend to overfit to noise. Each line is thus
* represented by three coefficients: c2 * x^2 + c1 * x + c0.
* Using the coefficients, sample each fitted curve uniformly
* across the full width of the image. */
sampling = dew->sampling;
nx = dew->nx;
ny = dew->ny;
ptaa3 = ptaaCreate(nlines);
nacurve = numaCreate(nlines); /* stores curvature coeff c2 */
for (i = 0; i < nlines; i++) { /* for each line */
pta = ptaaGetPta(ptaa2, i, L_CLONE);
ptaGetQuadraticLSF(pta, &c2, &c1, &c0, NULL);
numaAddNumber(nacurve, c2);
ptad = ptaCreate(nx);
for (j = 0; j < nx; j++) { /* uniformly sampled in x */
x = j * sampling;
applyQuadraticFit(c2, c1, c0, x, &y);
ptaAddPt(ptad, x, y);
}
ptaaAddPta(ptaa3, ptad, L_INSERT);
ptaDestroy(&pta);
}
if (debugflag) {
ptaa4 = ptaaCreate(nlines);
for (i = 0; i < nlines; i++) {
pta = ptaaGetPta(ptaa2, i, L_CLONE);
ptaGetArrays(pta, &nax, NULL);
ptaGetQuadraticLSF(pta, NULL, NULL, NULL, &nafit);
ptad = ptaCreateFromNuma(nax, nafit);
ptaaAddPta(ptaa4, ptad, L_INSERT);
ptaDestroy(&pta);
numaDestroy(&nax);
numaDestroy(&nafit);
}
pixt1 = pixConvertTo32(pixs);
pixt2 = pixDisplayPtaa(pixt1, ptaa4);
pixWriteTempfile("/tmp", "lines3.png", pixt2, IFF_PNG, NULL);
pixDestroy(&pixt1);
pixDestroy(&pixt2);
ptaaDestroy(&ptaa4);
}
/* Find and save the flat points in each curve. */
naflat = numaCreate(nlines);
for (i = 0; i < nlines; i++) {
pta = ptaaGetPta(ptaa3, i, L_CLONE);
numaGetFValue(nacurve, i, &c2);
if (c2 <= 0) /* flat point at bottom; max value of y in curve */
ptaGetRange(pta, NULL, NULL, NULL, &flaty);
else /* flat point at top; min value of y in curve */
ptaGetRange(pta, NULL, NULL, &flaty, NULL);
numaAddNumber(naflat, flaty);
ptaDestroy(&pta);
}
/* Sort the lines in ptaa3 by their position */
naflatsi = numaGetSortIndex(naflat, L_SORT_INCREASING);
naflats = numaSortByIndex(naflat, naflatsi);
nacurves = numaSortByIndex(nacurve, naflatsi);
dew->naflats = naflats;
dew->nacurves = nacurves;
ptaa4 = ptaaSortByIndex(ptaa3, naflatsi);
numaDestroy(&naflat);
numaDestroy(&nacurve);
numaDestroy(&naflatsi);
if (debugflag) {
tempname = genTempFilename("/tmp", "naflats.na", 0);
numaWrite(tempname, naflats);
FREE(tempname);
}
/* Convert the sampled points in ptaa3 to a sampled disparity with
* with respect to the flat point in the curve. */
ptaa5 = ptaaCreate(nlines);
for (i = 0; i < nlines; i++) {
pta = ptaaGetPta(ptaa4, i, L_CLONE);
numaGetFValue(naflats, i, &flaty);
ptad = ptaCreate(nx);
for (j = 0; j < nx; j++) {
ptaGetPt(pta, j, &x, &y);
ptaAddPt(ptad, x, flaty - y);
}
ptaaAddPta(ptaa5, ptad, L_INSERT);
ptaDestroy(&pta);
}
if (debugflag) {
tempname = genTempFilename("/tmp", "ptaa5.ptaa", 0);
ptaaWrite(tempname, ptaa5, 0);
FREE(tempname);
}
/* Generate a ptaa taking vertical 'columns' from ptaa5.
* We want to fit the vertical disparity on the column to the
* vertical position of the line, which we call 'y' here and
* obtain from naflats. */
ptaa6 = ptaaCreate(nx);
faflats = numaGetFArray(naflats, L_NOCOPY);
for (j = 0; j < nx; j++) {
pta = ptaCreate(nlines);
for (i = 0; i < nlines; i++) {
y = faflats[i];
ptaaGetPt(ptaa5, i, j, NULL, &val); /* disparity value */
ptaAddPt(pta, y, val);
}
ptaaAddPta(ptaa6, pta, L_INSERT);
}
if (debugflag) {
tempname = genTempFilename("/tmp", "ptaa6.ptaa", 0);
ptaaWrite(tempname, ptaa6, 0);
FREE(tempname);
}
/* Do quadratic fit vertically on a subset of pixel columns
* for the vertical displacement, which identifies the
* src pixel(s) for each dest pixel. Sample the displacement
* on a regular grid in the vertical direction. */
ptaa7 = ptaaCreate(nx); /* uniformly sampled across full height of image */
for (j = 0; j < nx; j++) { /* for each column */
pta = ptaaGetPta(ptaa6, j, L_CLONE);
ptaGetQuadraticLSF(pta, &c2, &c1, &c0, NULL);
ptad = ptaCreate(ny);
for (i = 0; i < ny; i++) { /* uniformly sampled in y */
y = i * sampling;
applyQuadraticFit(c2, c1, c0, y, &val);
ptaAddPt(ptad, y, val);
}
ptaaAddPta(ptaa7, ptad, L_INSERT);
ptaDestroy(&pta);
}
if (debugflag) {
tempname = genTempFilename("/tmp", "ptaa7.ptaa", 0);
ptaaWrite(tempname, ptaa7, 0);
FREE(tempname);
}
/* Save the result in a fpix at the specified subsampling */
fpix1 = fpixCreate(nx, ny);
for (i = 0; i < ny; i++) {
for (j = 0; j < nx; j++) {
ptaaGetPt(ptaa7, j, i, NULL, &val);
fpixSetPixel(fpix1, j, i, val);
}
}
dew->sampvdispar = fpix1;
/* Generate a full res fpix for vertical dewarping. We require that
* the size of this fpix is at least as big as the input image. */
fpix2 = fpixScaleByInteger(fpix1, sampling);
dew->fullvdispar = fpix2;
if (debugflag) {
pixt1 = fpixRenderContours(fpix2, -2., 2.0, 0.2);
pixWriteTempfile("/tmp", "vert-contours.png", pixt1, IFF_PNG, NULL);
pixDisplay(pixt1, 1000, 0);
pixDestroy(&pixt1);
}
/* Generate full res and sampled fpix for horizontal dewarping. This
* works to the extent that the line curvature is due to bending
* out of the plane normal to the camera, and not wide-angle
* "fishbowl" distortion. Also generate the sampled horizontal
* disparity array. */
if (dew->applyhoriz) {
fpix3 = fpixBuildHorizontalDisparity(fpix2, 0, &dew->extraw);
dew->fullhdispar = fpix3;
dew->samphdispar = fpixSampledDisparity(fpix3, dew->sampling);
if (debugflag) {
pixt1 = fpixRenderContours(fpix3, -2., 2.0, 0.2);
pixWriteTempfile("/tmp", "horiz-contours.png", pixt1,
IFF_PNG, NULL);
pixDisplay(pixt1, 1000, 0);
pixDestroy(&pixt1);
}
}
dew->success = 1;
ptaaDestroy(&ptaa1);
ptaaDestroy(&ptaa2);
ptaaDestroy(&ptaa3);
ptaaDestroy(&ptaa4);
ptaaDestroy(&ptaa5);
ptaaDestroy(&ptaa6);
ptaaDestroy(&ptaa7);
return 0;
}
/*!
* boxaSort2d()
*
* Input: boxas
* &naa (<optional return> numaa with sorted indices
* whose values are the indices of the input array)
* delta1 (min overlap that permits aggregation of a box
* onto a boxa of horizontally-aligned boxes; pass 1)
* delta2 (min overlap that permits aggregation of a box
* onto a boxa of horizontally-aligned boxes; pass 2)
* minh1 (components less than this height either join an
* existing boxa or are set aside for pass 2)
* Return: boxaa (2d sorted version of boxa), or null on error
*
* Notes:
* (1) The final result is a sort where the 'fast scan' direction is
* left to right, and the 'slow scan' direction is from top
* to bottom. Each boxa in the boxaa represents a sorted set
* of boxes from left to right.
* (2) Two passes are used to aggregate the boxas, which can corresond
* to characters or words in a line of text. In pass 1, only
* taller components, which correspond to xheight or larger,
* are permitted to start a new boxa, whereas in pass 2,
* the remaining vertically-challenged components are allowed
* to join an existing boxa or start a new one.
* (3) If delta1 < 0, the first pass allows aggregation when
* boxes in the same boxa do not overlap vertically.
* The distance by which they can miss and still be aggregated
* is the absolute value |delta1|. Similar for delta2 on
* the second pass.
* (4) On the first pass, any component of height less than minh1
* cannot start a new boxa; it's put aside for later insertion.
* (5) On the second pass, any small component that doesn't align
* with an existing boxa can start a new one.
* (6) This can be used to identify lines of text from
* character or word bounding boxes.
*/
BOXAA *
boxaSort2d(BOXA *boxas,
NUMAA **pnaad,
l_int32 delta1,
l_int32 delta2,
l_int32 minh1)
{
l_int32 i, index, h, nt, ne, n, m, ival;
BOX *box;
BOXA *boxa, *boxae, *boxan, *boxat1, *boxat2, *boxav, *boxavs;
BOXAA *baa, *baad;
NUMA *naindex, *nae, *nan, *nah, *nav, *nat1, *nat2, *nad;
NUMAA *naa, *naad;
PROCNAME("boxaSort2d");
if (pnaad) *pnaad = NULL;
if (!boxas)
return (BOXAA *)ERROR_PTR("boxas not defined", procName, NULL);
/* Sort from left to right */
if ((boxa = boxaSort(boxas, L_SORT_BY_X, L_SORT_INCREASING, &naindex))
== NULL)
return (BOXAA *)ERROR_PTR("boxa not made", procName, NULL);
/* First pass: assign taller boxes to boxa by row */
nt = boxaGetCount(boxa);
baa = boxaaCreate(0);
naa = numaaCreate(0);
boxae = boxaCreate(0); /* save small height boxes here */
nae = numaCreate(0); /* keep track of small height boxes */
for (i = 0; i < nt; i++) {
box = boxaGetBox(boxa, i, L_CLONE);
boxGetGeometry(box, NULL, NULL, NULL, &h);
if (h < minh1) { /* save for 2nd pass */
boxaAddBox(boxae, box, L_INSERT);
numaAddNumber(nae, i);
}
else {
n = boxaaGetCount(baa);
boxaaAlignBox(baa, box, delta1, &index);
if (index < n) { /* append to an existing boxa */
boxaaAddBox(baa, index, box, L_INSERT);
}
else { /* doesn't align, need new boxa */
boxan = boxaCreate(0);
boxaAddBox(boxan, box, L_INSERT);
boxaaAddBoxa(baa, boxan, L_INSERT);
nan = numaCreate(0);
numaaAddNuma(naa, nan, L_INSERT);
}
numaGetIValue(naindex, i, &ival);
numaaAddNumber(naa, index, ival);
}
}
boxaDestroy(&boxa);
numaDestroy(&naindex);
/* Second pass: feed in small height boxes;
* TODO: this correctly, using local y position! */
ne = boxaGetCount(boxae);
for (i = 0; i < ne; i++) {
box = boxaGetBox(boxae, i, L_CLONE);
n = boxaaGetCount(baa);
boxaaAlignBox(baa, box, delta2, &index);
if (index < n) { /* append to an existing boxa */
boxaaAddBox(baa, index, box, L_INSERT);
}
else { /* doesn't align, need new boxa */
boxan = boxaCreate(0);
boxaAddBox(boxan, box, L_INSERT);
boxaaAddBoxa(baa, boxan, L_INSERT);
nan = numaCreate(0);
numaaAddNuma(naa, nan, L_INSERT);
}
numaGetIValue(nae, i, &ival); /* location in original boxas */
numaaAddNumber(naa, index, ival);
}
/* Sort each boxa in the boxaa */
m = boxaaGetCount(baa);
for (i = 0; i < m; i++) {
boxat1 = boxaaGetBoxa(baa, i, L_CLONE);
boxat2 = boxaSort(boxat1, L_SORT_BY_X, L_SORT_INCREASING, &nah);
boxaaReplaceBoxa(baa, i, boxat2);
nat1 = numaaGetNuma(naa, i, L_CLONE);
nat2 = numaSortByIndex(nat1, nah);
numaaReplaceNuma(naa, i, nat2);
boxaDestroy(&boxat1);
numaDestroy(&nat1);
numaDestroy(&nah);
}
/* Sort boxa vertically within boxaa, using the first box
* in each boxa. */
m = boxaaGetCount(baa);
boxav = boxaCreate(m); /* holds first box in each boxa in baa */
naad = numaaCreate(m);
if (pnaad)
*pnaad = naad;
baad = boxaaCreate(m);
for (i = 0; i < m; i++) {
boxat1 = boxaaGetBoxa(baa, i, L_CLONE);
box = boxaGetBox(boxat1, 0, L_CLONE);
boxaAddBox(boxav, box, L_INSERT);
boxaDestroy(&boxat1);
}
boxavs = boxaSort(boxav, L_SORT_BY_Y, L_SORT_INCREASING, &nav);
for (i = 0; i < m; i++) {
numaGetIValue(nav, i, &index);
boxa = boxaaGetBoxa(baa, index, L_CLONE);
boxaaAddBoxa(baad, boxa, L_INSERT);
nad = numaaGetNuma(naa, index, L_CLONE);
numaaAddNuma(naad, nad, L_INSERT);
}
/* fprintf(stderr, "box count = %d, numaa count = %d\n", nt,
numaaGetNumberCount(naad)); */
boxaaDestroy(&baa);
boxaDestroy(&boxav);
boxaDestroy(&boxavs);
boxaDestroy(&boxae);
numaDestroy(&nav);
numaDestroy(&nae);
numaaDestroy(&naa);
if (!pnaad)
numaaDestroy(&naad);
return baad;
}
