void PixelHistogram::ConstructHorizontalCountHist(Pix* pix) {
Clear();
Numa* counts = pixCountPixelsByRow(pix, NULL);
length_ = numaGetCount(counts);
hist_ = new int[length_];
for (int i = 0; i < length_; ++i) {
l_int32 val = 0;
numaGetIValue(counts, i, &val);
hist_[i] = val;
}
numaDestroy(&counts);
}
/*!
* \brief pixFindDifferentialSquareSum()
*
* \param[in] pixs
* \param[out] psum result
* \return 0 if OK, 1 on error
*
* <pre>
* Notes:
* (1) At the top and bottom, we skip:
* ~ at least one scanline
* ~ not more than 10% of the image height
* ~ not more than 5% of the image width
* </pre>
*/
l_int32
pixFindDifferentialSquareSum(PIX *pixs,
l_float32 *psum)
{
l_int32 i, n;
l_int32 w, h, skiph, skip, nskip;
l_float32 val1, val2, diff, sum;
NUMA *na;
PROCNAME("pixFindDifferentialSquareSum");
if (!psum)
return ERROR_INT("&sum not defined", procName, 1);
*psum = 0.0;
if (!pixs)
return ERROR_INT("pixs not defined", procName, 1);
/* Generate a number array consisting of the sum
* of pixels in each row of pixs */
if ((na = pixCountPixelsByRow(pixs, NULL)) == NULL)
return ERROR_INT("na not made", procName, 1);
/* Compute the number of rows at top and bottom to omit.
* We omit these to avoid getting a spurious signal from
* the top and bottom of a (nearly) all black image. */
w = pixGetWidth(pixs);
h = pixGetHeight(pixs);
skiph = (l_int32)(0.05 * w); /* skip for max shear of 0.025 radians */
skip = L_MIN(h / 10, skiph); /* don't remove more than 10% of image */
nskip = L_MAX(skip / 2, 1); /* at top & bot; skip at least one line */
/* Sum the squares of differential row sums, on the
* allowed rows. Note that nskip must be >= 1. */
n = numaGetCount(na);
sum = 0.0;
for (i = nskip; i < n - nskip; i++) {
numaGetFValue(na, i - 1, &val1);
numaGetFValue(na, i, &val2);
diff = val2 - val1;
sum += diff * diff;
}
numaDestroy(&na);
*psum = sum;
return 0;
}
/*!
* pixGetTextBaseline()
*
* Input: pixs (1 bpp, one textline character set)
* tab8 (<optional> pixel sum table)
* &y (<return> baseline value)
* Return: 0 if OK, 1 on error
*
* Notes:
* (1) Method: find the largest difference in pixel sums from one
* raster line to the next one below it. The baseline is the
* upper raster line for the pair of raster lines that
* maximizes this function.
*/
static l_int32
pixGetTextBaseline(PIX *pixs,
l_int32 *tab8,
l_int32 *py)
{
l_int32 i, h, val1, val2, diff, diffmax, ymax;
l_int32 *tab;
NUMA *na;
PROCNAME("pixGetTextBaseline");
if (!pixs)
return ERROR_INT("pixs not defined", procName, 1);
if (!py)
return ERROR_INT("&y not defined", procName, 1);
*py = 0;
if (!tab8)
tab = makePixelSumTab8();
else
tab = tab8;
na = pixCountPixelsByRow(pixs, tab);
h = numaGetCount(na);
diffmax = 0;
ymax = 0;
for (i = 1; i < h; i++) {
numaGetIValue(na, i - 1, &val1);
numaGetIValue(na, i, &val2);
diff = L_MAX(0, val1 - val2);
if (diff > diffmax) {
diffmax = diff;
ymax = i - 1; /* upper raster line */
}
}
*py = ymax;
if (!tab8)
FREE(tab);
numaDestroy(&na);
return 0;
}
/*!
* \brief pixFindBaselines()
*
* \param[in] pixs 1 bpp, 300 ppi
* \param[out] ppta [optional] pairs of pts corresponding to
* approx. ends of each text line
* \param[in] pixadb for debug output; use NULL to skip
* \return na of baseline y values, or NULL on error
*
* <pre>
* Notes:
* (1) Input binary image must have text lines already aligned
* horizontally. This can be done by either rotating the
* image with pixDeskew(), or, if a projective transform
* is required, by doing pixDeskewLocal() first.
* (2) Input null for &pta if you don't want this returned.
* The pta will come in pairs of points (left and right end
* of each baseline).
* (3) Caution: this will not work properly on text with multiple
* columns, where the lines are not aligned between columns.
* If there are multiple columns, they should be extracted
* separately before finding the baselines.
* (4) This function constructs different types of output
* for baselines; namely, a set of raster line values and
* a set of end points of each baseline.
* (5) This function was designed to handle short and long text lines
* without using dangerous thresholds on the peak heights. It does
* this by combining the differential signal with a morphological
* analysis of the locations of the text lines. One can also
* combine this data to normalize the peak heights, by weighting
* the differential signal in the region of each baseline
* by the inverse of the width of the text line found there.
* </pre>
*/
NUMA *
pixFindBaselines(PIX *pixs,
PTA **ppta,
PIXA *pixadb)
{
l_int32 h, i, j, nbox, val1, val2, ndiff, bx, by, bw, bh;
l_int32 imaxloc, peakthresh, zerothresh, inpeak;
l_int32 mintosearch, max, maxloc, nloc, locval;
l_int32 *array;
l_float32 maxval;
BOXA *boxa1, *boxa2, *boxa3;
GPLOT *gplot;
NUMA *nasum, *nadiff, *naloc, *naval;
PIX *pix1, *pix2;
PTA *pta;
PROCNAME("pixFindBaselines");
if (ppta) *ppta = NULL;
if (!pixs || pixGetDepth(pixs) != 1)
return (NUMA *)ERROR_PTR("pixs undefined or not 1 bpp", procName, NULL);
/* Close up the text characters, removing noise */
pix1 = pixMorphSequence(pixs, "c25.1 + e15.1", 0);
/* Estimate the resolution */
if (pixadb) pixaAddPix(pixadb, pixScale(pix1, 0.25, 0.25), L_INSERT);
/* Save the difference of adjacent row sums.
* The high positive-going peaks are the baselines */
if ((nasum = pixCountPixelsByRow(pix1, NULL)) == NULL) {
pixDestroy(&pix1);
return (NUMA *)ERROR_PTR("nasum not made", procName, NULL);
}
h = pixGetHeight(pixs);
nadiff = numaCreate(h);
numaGetIValue(nasum, 0, &val2);
for (i = 0; i < h - 1; i++) {
val1 = val2;
numaGetIValue(nasum, i + 1, &val2);
numaAddNumber(nadiff, val1 - val2);
}
numaDestroy(&nasum);
if (pixadb) { /* show the difference signal */
lept_mkdir("lept/baseline");
gplotSimple1(nadiff, GPLOT_PNG, "/tmp/lept/baseline/diff", "Diff Sig");
pix2 = pixRead("/tmp/lept/baseline/diff.png");
pixaAddPix(pixadb, pix2, L_INSERT);
}
/* Use the zeroes of the profile to locate each baseline. */
array = numaGetIArray(nadiff);
ndiff = numaGetCount(nadiff);
numaGetMax(nadiff, &maxval, &imaxloc);
numaDestroy(&nadiff);
/* Use this to begin locating a new peak: */
peakthresh = (l_int32)maxval / PEAK_THRESHOLD_RATIO;
/* Use this to begin a region between peaks: */
zerothresh = (l_int32)maxval / ZERO_THRESHOLD_RATIO;
naloc = numaCreate(0);
naval = numaCreate(0);
inpeak = FALSE;
for (i = 0; i < ndiff; i++) {
if (inpeak == FALSE) {
if (array[i] > peakthresh) { /* transition to in-peak */
inpeak = TRUE;
mintosearch = i + MIN_DIST_IN_PEAK; /* accept no zeros
* between i and mintosearch */
max = array[i];
maxloc = i;
}
} else { /* inpeak == TRUE; look for max */
if (array[i] > max) {
max = array[i];
maxloc = i;
mintosearch = i + MIN_DIST_IN_PEAK;
} else if (i > mintosearch && array[i] <= zerothresh) { /* leave */
inpeak = FALSE;
numaAddNumber(naval, max);
numaAddNumber(naloc, maxloc);
}
}
}
LEPT_FREE(array);
/* If array[ndiff-1] is max, eg. no descenders, baseline at bottom */
if (inpeak) {
numaAddNumber(naval, max);
numaAddNumber(naloc, maxloc);
}
if (pixadb) { /* show the raster locations for the peaks */
gplot = gplotCreate("/tmp/lept/baseline/loc", GPLOT_PNG, "Peak locs",
"rasterline", "height");
gplotAddPlot(gplot, naloc, naval, GPLOT_POINTS, "locs");
gplotMakeOutput(gplot);
gplotDestroy(&gplot);
pix2 = pixRead("/tmp/lept/baseline/loc.png");
pixaAddPix(pixadb, pix2, L_INSERT);
}
numaDestroy(&naval);
/* Generate an approximate profile of text line width.
* First, filter the boxes of text, where there may be
* more than one box for a given textline. */
pix2 = pixMorphSequence(pix1, "r11 + c20.1 + o30.1 +c1.3", 0);
if (pixadb) pixaAddPix(pixadb, pix2, L_COPY);
boxa1 = pixConnComp(pix2, NULL, 4);
pixDestroy(&pix1);
pixDestroy(&pix2);
if (boxaGetCount(boxa1) == 0) {
numaDestroy(&naloc);
boxaDestroy(&boxa1);
L_INFO("no compnents after filtering\n", procName);
return NULL;
}
boxa2 = boxaTransform(boxa1, 0, 0, 4., 4.);
boxa3 = boxaSort(boxa2, L_SORT_BY_Y, L_SORT_INCREASING, NULL);
boxaDestroy(&boxa1);
boxaDestroy(&boxa2);
/* Optionally, find the baseline segments */
pta = NULL;
if (ppta) {
pta = ptaCreate(0);
*ppta = pta;
}
if (pta) {
nloc = numaGetCount(naloc);
nbox = boxaGetCount(boxa3);
for (i = 0; i < nbox; i++) {
boxaGetBoxGeometry(boxa3, i, &bx, &by, &bw, &bh);
for (j = 0; j < nloc; j++) {
numaGetIValue(naloc, j, &locval);
if (L_ABS(locval - (by + bh)) > 25)
continue;
ptaAddPt(pta, bx, locval);
ptaAddPt(pta, bx + bw, locval);
break;
}
}
}
boxaDestroy(&boxa3);
if (pixadb && pta) { /* display baselines */
l_int32 npts, x1, y1, x2, y2;
pix1 = pixConvertTo32(pixs);
npts = ptaGetCount(pta);
for (i = 0; i < npts; i += 2) {
ptaGetIPt(pta, i, &x1, &y1);
ptaGetIPt(pta, i + 1, &x2, &y2);
pixRenderLineArb(pix1, x1, y1, x2, y2, 2, 255, 0, 0);
}
pixWrite("/tmp/lept/baseline/baselines.png", pix1, IFF_PNG);
pixaAddPix(pixadb, pixScale(pix1, 0.25, 0.25), L_INSERT);
pixDestroy(&pix1);
}
return naloc;
}
/*!
* pixaGenerateFont()
*
* Input: pix (of 95 characters in 3 rows)
* fontsize (4, 6, 8, ... , 20, in pts at 300 ppi)
* &bl1 (<return> baseline of row 1)
* &bl2 (<return> baseline of row 2)
* &bl3 (<return> baseline of row 3)
* Return: pixa of font bitmaps for 95 characters, or null on error
*
* Notes:
* (1) This does all the work. See pixaGenerateFontFromFile()
* for an overview.
* (2) The pix is for one of the 9 fonts. @fontsize is only
* used here for debugging.
*/
PIXA *
pixaGenerateFont(PIX *pixs,
l_int32 fontsize,
l_int32 *pbl0,
l_int32 *pbl1,
l_int32 *pbl2)
{
l_int32 i, j, nrows, nrowchars, nchars, h, yval;
l_int32 width, height;
l_int32 baseline[3];
l_int32 *tab = NULL;
BOX *box, *box1, *box2;
BOXA *boxar, *boxac, *boxacs;
PIX *pix1, *pix2, *pixr, *pixrc, *pixc;
PIXA *pixa;
l_int32 n, w, inrow, top;
l_int32 *ia;
NUMA *na;
PROCNAME("pixaGenerateFont");
if (!pbl0 || !pbl1 || !pbl2)
return (PIXA *)ERROR_PTR("&bl not all defined", procName, NULL);
*pbl0 = *pbl1 = *pbl2 = 0;
if (!pixs)
return (PIXA *)ERROR_PTR("pixs not defined", procName, NULL);
/* Locate the 3 rows of characters */
w = pixGetWidth(pixs);
na = pixCountPixelsByRow(pixs, NULL);
boxar = boxaCreate(0);
n = numaGetCount(na);
ia = numaGetIArray(na);
inrow = 0;
for (i = 0; i < n; i++) {
if (!inrow && ia[i] > 0) {
inrow = 1;
top = i;
} else if (inrow && ia[i] == 0) {
inrow = 0;
box = boxCreate(0, top, w, i - top);
boxaAddBox(boxar, box, L_INSERT);
}
}
FREE(ia);
numaDestroy(&na);
nrows = boxaGetCount(boxar);
#if DEBUG_FONT_GEN
L_INFO("For fontsize %s, have %d rows\n", procName, fontsize, nrows);
#endif /* DEBUG_FONT_GEN */
if (nrows != 3) {
L_INFO("nrows = %d; skipping fontsize %d\n", procName, nrows, fontsize);
return (PIXA *)ERROR_PTR("3 rows not generated", procName, NULL);
}
/* Grab the character images and baseline data */
#if DEBUG_BASELINE
lept_rmdir("baseline");
lept_mkdir("baseline");
#endif /* DEBUG_BASELINE */
tab = makePixelSumTab8();
pixa = pixaCreate(95);
for (i = 0; i < nrows; i++) {
box = boxaGetBox(boxar, i, L_CLONE);
pixr = pixClipRectangle(pixs, box, NULL); /* row of chars */
pixGetTextBaseline(pixr, tab, &yval);
baseline[i] = yval;
#if DEBUG_BASELINE
L_INFO("Baseline info: row %d, yval = %d, h = %d\n", procName,
i, yval, pixGetHeight(pixr));
pix1 = pixCopy(NULL, pixr);
pixRenderLine(pix1, 0, yval, pixGetWidth(pix1), yval, 1,
L_FLIP_PIXELS);
if (i == 0 )
pixWrite("/tmp/baseline/row0.png", pix1, IFF_PNG);
else if (i == 1)
pixWrite("/tmp/baseline/row1.png", pix1, IFF_PNG);
else
pixWrite("/tmp/baseline/row2.png", pix1, IFF_PNG);
pixDestroy(&pix1);
#endif /* DEBUG_BASELINE */
boxDestroy(&box);
pixrc = pixCloseSafeBrick(NULL, pixr, 1, 35);
boxac = pixConnComp(pixrc, NULL, 8);
boxacs = boxaSort(boxac, L_SORT_BY_X, L_SORT_INCREASING, NULL);
if (i == 0) { /* consolidate the two components of '"' */
box1 = boxaGetBox(boxacs, 1, L_CLONE);
box2 = boxaGetBox(boxacs, 2, L_CLONE);
box1->w = box2->x + box2->w - box1->x; /* increase width */
boxDestroy(&box1);
boxDestroy(&box2);
boxaRemoveBox(boxacs, 2);
}
h = pixGetHeight(pixr);
nrowchars = boxaGetCount(boxacs);
for (j = 0; j < nrowchars; j++) {
box = boxaGetBox(boxacs, j, L_COPY);
if (box->w <= 2 && box->h == 1) { /* skip 1x1, 2x1 components */
boxDestroy(&box);
continue;
}
box->y = 0;
box->h = h - 1;
pixc = pixClipRectangle(pixr, box, NULL);
boxDestroy(&box);
if (i == 0 && j == 0) /* add a pix for the space; change later */
pixaAddPix(pixa, pixc, L_COPY);
if (i == 2 && j == 0) /* add a pix for the '\'; change later */
pixaAddPix(pixa, pixc, L_COPY);
pixaAddPix(pixa, pixc, L_INSERT);
}
pixDestroy(&pixr);
pixDestroy(&pixrc);
boxaDestroy(&boxac);
boxaDestroy(&boxacs);
}
FREE(tab);
nchars = pixaGetCount(pixa);
if (nchars != 95)
return (PIXA *)ERROR_PTR("95 chars not generated", procName, NULL);
*pbl0 = baseline[0];
*pbl1 = baseline[1];
*pbl2 = baseline[2];
/* Fix the space character up; it should have no ON pixels,
* and be about twice as wide as the '!' character. */
pix1 = pixaGetPix(pixa, 0, L_CLONE);
width = 2 * pixGetWidth(pix1);
height = pixGetHeight(pix1);
pixDestroy(&pix1);
pix1 = pixCreate(width, height, 1);
pixaReplacePix(pixa, 0, pix1, NULL);
/* Fix up the '\' character; use a LR flip of the '/' char */
pix1 = pixaGetPix(pixa, 15, L_CLONE);
pix2 = pixFlipLR(NULL, pix1);
pixDestroy(&pix1);
pixaReplacePix(pixa, 60, pix2, NULL);
#if DEBUG_CHARS
pix1 = pixaDisplayTiled(pixa, 1500, 0, 10);
pixDisplay(pix1, 100 * i, 200);
pixDestroy(&pix1);
#endif /* DEBUG_CHARS */
boxaDestroy(&boxar);
return pixa;
}
/*!
* pixFindNormalizedSquareSum()
*
* Input: pixs
* &hratio (<optional return> ratio of normalized horiz square sum
* to result if the pixel distribution were uniform)
* &vratio (<optional return> ratio of normalized vert square sum
* to result if the pixel distribution were uniform)
* &fract (<optional return> ratio of fg pixels to total pixels)
* Return: 0 if OK, 1 on error or if there are no fg pixels
*
* Notes:
* (1) Let the image have h scanlines and N fg pixels.
* If the pixels were uniformly distributed on scanlines,
* the sum of squares of fg pixels on each scanline would be
* h * (N / h)^2. However, if the pixels are not uniformly
* distributed (e.g., for text), the sum of squares of fg
* pixels will be larger. We return in hratio and vratio the
* ratio of these two values.
* (2) If there are no fg pixels, hratio and vratio are returned as 0.0.
*/
l_int32
pixFindNormalizedSquareSum(PIX *pixs,
l_float32 *phratio,
l_float32 *pvratio,
l_float32 *pfract)
{
l_int32 i, w, h, empty;
l_float32 sum, sumsq, uniform, val;
NUMA *na;
PIX *pixt;
PROCNAME("pixFindNormalizedSquareSum");
if (!pixs || pixGetDepth(pixs) != 1)
return ERROR_INT("pixs not defined or not 1 bpp", procName, 1);
pixGetDimensions(pixs, &w, &h, NULL);
if (!phratio && !pvratio)
return ERROR_INT("nothing to do", procName, 1);
if (phratio) *phratio = 0.0;
if (pvratio) *pvratio = 0.0;
empty = 0;
if (phratio) {
na = pixCountPixelsByRow(pixs, NULL);
numaGetSum(na, &sum); /* fg pixels */
if (pfract) *pfract = sum / (l_float32)(w * h);
if (sum != 0.0) {
uniform = sum * sum / h; /* h*(sum / h)^2 */
sumsq = 0.0;
for (i = 0; i < h; i++) {
numaGetFValue(na, i, &val);
sumsq += val * val;
}
*phratio = sumsq / uniform;
} else {
empty = 1;
}
numaDestroy(&na);
}
if (pvratio) {
if (empty == 1) return 1;
pixt = pixRotateOrth(pixs, 1);
na = pixCountPixelsByRow(pixt, NULL);
numaGetSum(na, &sum);
if (pfract) *pfract = sum / (l_float32)(w * h);
if (sum != 0.0) {
uniform = sum * sum / w;
sumsq = 0.0;
for (i = 0; i < w; i++) {
numaGetFValue(na, i, &val);
sumsq += val * val;
}
*pvratio = sumsq / uniform;
} else {
empty = 1;
}
pixDestroy(&pixt);
numaDestroy(&na);
}
return empty;
}