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tesseract/ccmain/equationdetect.cpp

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///////////////////////////////////////////////////////////////////////
// File: equationdetect.cpp
// Description: Helper classes to detect equations.
// Author: Zongyi (Joe) Liu (joeliu@google.com)
// Created: Fri Aug 31 11:13:01 PST 2011
//
// (C) Copyright 2011, Google Inc.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
///////////////////////////////////////////////////////////////////////
#ifdef _MSC_VER
#pragma warning(disable:4244) // Conversion warnings
#include <mathfix.h>
#endif
#ifdef __MINGW32__
#include <limits.h>
#endif
#include <float.h>
// Include automatically generated configuration file if running autoconf.
#ifdef HAVE_CONFIG_H
#include "config_auto.h"
#endif
#include "equationdetect.h"
#include "bbgrid.h"
#include "classify.h"
#include "colpartition.h"
#include "colpartitiongrid.h"
#include "colpartitionset.h"
#include "helpers.h"
#include "ratngs.h"
#include "tesseractclass.h"
// Config variables.
BOOL_VAR(equationdetect_save_bi_image, false, "Save input bi image");
BOOL_VAR(equationdetect_save_spt_image, false, "Save special character image");
BOOL_VAR(equationdetect_save_seed_image, false, "Save the seed image");
BOOL_VAR(equationdetect_save_merged_image, false, "Save the merged image");
namespace tesseract {
///////////////////////////////////////////////////////////////////////////
// Utility ColParition sort functions.
///////////////////////////////////////////////////////////////////////////
static int SortCPByTopReverse(const void* p1, const void* p2) {
const ColPartition* cp1 = *reinterpret_cast<ColPartition* const*>(p1);
const ColPartition* cp2 = *reinterpret_cast<ColPartition* const*>(p2);
ASSERT_HOST(cp1 != NULL && cp2 != NULL);
const TBOX &box1(cp1->bounding_box()), &box2(cp2->bounding_box());
return box2.top() - box1.top();
}
static int SortCPByBottom(const void* p1, const void* p2) {
const ColPartition* cp1 = *reinterpret_cast<ColPartition* const*>(p1);
const ColPartition* cp2 = *reinterpret_cast<ColPartition* const*>(p2);
ASSERT_HOST(cp1 != NULL && cp2 != NULL);
const TBOX &box1(cp1->bounding_box()), &box2(cp2->bounding_box());
return box1.bottom() - box2.bottom();
}
static int SortCPByHeight(const void* p1, const void* p2) {
const ColPartition* cp1 = *reinterpret_cast<ColPartition* const*>(p1);
const ColPartition* cp2 = *reinterpret_cast<ColPartition* const*>(p2);
ASSERT_HOST(cp1 != NULL && cp2 != NULL);
const TBOX &box1(cp1->bounding_box()), &box2(cp2->bounding_box());
return box1.height() - box2.height();
}
// TODO(joeliu): we may want to parameterize these constants.
const float kMathDigitDensityTh1 = 0.25;
const float kMathDigitDensityTh2 = 0.1;
const float kMathItalicDensityTh = 0.5;
const float kUnclearDensityTh = 0.25;
const int kSeedBlobsCountTh = 10;
const int kLeftIndentAlignmentCountTh = 1;
// Returns true if PolyBlockType is of text type or equation type.
inline bool IsTextOrEquationType(PolyBlockType type) {
return PTIsTextType(type) || type == PT_EQUATION;
}
inline bool IsLeftIndented(const EquationDetect::IndentType type) {
return type == EquationDetect::LEFT_INDENT ||
type == EquationDetect::BOTH_INDENT;
}
inline bool IsRightIndented(const EquationDetect::IndentType type) {
return type == EquationDetect::RIGHT_INDENT ||
type == EquationDetect::BOTH_INDENT;
}
EquationDetect::EquationDetect(const char* equ_datapath,
const char* equ_name) {
const char* default_name = "equ";
if (equ_name == NULL) {
equ_name = default_name;
}
equ_tesseract_ = lang_tesseract_ = NULL;
resolution_ = 0;
page_count_ = 0;
// Construct equ_tesseract_.
equ_tesseract_ = new Tesseract();
if (equ_tesseract_->init_tesseract(equ_datapath, equ_name,
OEM_TESSERACT_ONLY)) {
tprintf("Warning: equation region detection requested,"
" but %s failed to load from %s\n", equ_name, equ_datapath);
delete equ_tesseract_;
equ_tesseract_ = NULL;
}
cps_super_bbox_ = NULL;
}
EquationDetect::~EquationDetect() {
if (equ_tesseract_) {
delete (equ_tesseract_);
}
if (cps_super_bbox_) {
delete(cps_super_bbox_);
}
}
void EquationDetect::SetLangTesseract(Tesseract* lang_tesseract) {
lang_tesseract_ = lang_tesseract;
}
void EquationDetect::SetResolution(const int resolution) {
resolution_ = resolution;
}
int EquationDetect::LabelSpecialText(TO_BLOCK* to_block) {
if (to_block == NULL) {
tprintf("Warning: input to_block is NULL!\n");
return -1;
}
GenericVector<BLOBNBOX_LIST*> blob_lists;
blob_lists.push_back(&(to_block->blobs));
blob_lists.push_back(&(to_block->large_blobs));
for (int i = 0; i < blob_lists.size(); ++i) {
BLOBNBOX_IT bbox_it(blob_lists[i]);
for (bbox_it.mark_cycle_pt (); !bbox_it.cycled_list();
bbox_it.forward()) {
bbox_it.data()->set_special_text_type(BSTT_NONE);
}
}
return 0;
}
void EquationDetect::IdentifySpecialText(
BLOBNBOX *blobnbox, const int height_th) {
ASSERT_HOST(blobnbox != NULL);
if (blobnbox->bounding_box().height() < height_th && height_th > 0) {
// For small blob, we simply set to BSTT_NONE.
blobnbox->set_special_text_type(BSTT_NONE);
return;
}
BLOB_CHOICE_LIST ratings_equ, ratings_lang;
C_BLOB* blob = blobnbox->cblob();
// TODO(joeliu/rays) Fix this. We may have to normalize separately for
// each classifier here, as they may require different PolygonalCopy.
TBLOB* tblob = TBLOB::PolygonalCopy(false, blob);
const TBOX& box = tblob->bounding_box();
// Normalize the blob. Set the origin to the place we want to be the
// bottom-middle, and scaling is to make the height the x-height.
float scaling = static_cast<float>(kBlnXHeight) / box.height();
float x_orig = (box.left() + box.right()) / 2.0f, y_orig = box.bottom();
TBLOB* normed_blob = new TBLOB(*tblob);
normed_blob->Normalize(NULL, NULL, NULL, x_orig, y_orig, scaling, scaling,
0.0f, static_cast<float>(kBlnBaselineOffset),
false, NULL);
equ_tesseract_->AdaptiveClassifier(normed_blob, &ratings_equ, NULL);
lang_tesseract_->AdaptiveClassifier(normed_blob, &ratings_lang, NULL);
delete normed_blob;
delete tblob;
// Get the best choice from ratings_lang and rating_equ. As the choice in the
// list has already been sorted by the certainty, we simply use the first
// choice.
BLOB_CHOICE *lang_choice = NULL, *equ_choice = NULL;
if (ratings_lang.length() > 0) {
BLOB_CHOICE_IT choice_it(&ratings_lang);
lang_choice = choice_it.data();
}
if (ratings_equ.length() > 0) {
BLOB_CHOICE_IT choice_it(&ratings_equ);
equ_choice = choice_it.data();
}
float lang_score = lang_choice ? lang_choice->certainty() : -FLT_MAX;
float equ_score = equ_choice ? equ_choice->certainty() : -FLT_MAX;
const float kConfScoreTh = -5.0f, kConfDiffTh = 1.8;
// The scores here are negative, so the max/min == fabs(min/max).
// float ratio = fmax(lang_score, equ_score) / fmin(lang_score, equ_score);
float diff = fabs(lang_score - equ_score);
BlobSpecialTextType type = BSTT_NONE;
// Classification.
if (fmax(lang_score, equ_score) < kConfScoreTh) {
// If both score are very small, then mark it as unclear.
type = BSTT_UNCLEAR;
} else if (diff > kConfDiffTh && equ_score > lang_score) {
// If equ_score is significantly higher, then we classify this character as
// math symbol.
type = BSTT_MATH;
} else if (lang_choice) {
// For other cases: lang_score is similar or significantly higher.
type = EstimateTypeForUnichar(
lang_tesseract_->unicharset, lang_choice->unichar_id());
}
if (type == BSTT_NONE && lang_tesseract_->get_fontinfo_table().get(
lang_choice->fontinfo_id()).is_italic()) {
// For text symbol, we still check if it is italic.
blobnbox->set_special_text_type(BSTT_ITALIC);
} else {
blobnbox->set_special_text_type(type);
}
}
BlobSpecialTextType EquationDetect::EstimateTypeForUnichar(
const UNICHARSET& unicharset, const UNICHAR_ID id) const {
STRING s = unicharset.id_to_unichar(id);
if (unicharset.get_isalpha(id)) {
return BSTT_NONE;
}
if (unicharset.get_ispunctuation(id)) {
// Exclude some special texts that are likely to be confused as math symbol.
static GenericVector<UNICHAR_ID> ids_to_exclude;
if (ids_to_exclude.empty()) {
static const STRING kCharsToEx[] = {"'", "`", "\"", "\\", ",", ".",
"〈", "〉", "《", "》", "」", "「", ""};
int i = 0;
while (kCharsToEx[i] != "") {
ids_to_exclude.push_back(
unicharset.unichar_to_id(kCharsToEx[i++].string()));
}
ids_to_exclude.sort();
}
return ids_to_exclude.bool_binary_search(id) ? BSTT_NONE : BSTT_MATH;
}
// Check if it is digit. In addition to the isdigit attribute, we also check
// if this character belongs to those likely to be confused with a digit.
static const STRING kDigitsChars = "|";
if (unicharset.get_isdigit(id) ||
(s.length() == 1 && kDigitsChars.contains(s[0]))) {
return BSTT_DIGIT;
} else {
return BSTT_MATH;
}
}
void EquationDetect::IdentifySpecialText() {
// Set configuration for Tesseract::AdaptiveClassifier.
equ_tesseract_->tess_cn_matching.set_value(true); // turn it on
equ_tesseract_->tess_bn_matching.set_value(false);
// Set the multiplier to zero for lang_tesseract_ to improve the accuracy.
int classify_class_pruner = lang_tesseract_->classify_class_pruner_multiplier;
int classify_integer_matcher =
lang_tesseract_->classify_integer_matcher_multiplier;
lang_tesseract_->classify_class_pruner_multiplier.set_value(0);
lang_tesseract_->classify_integer_matcher_multiplier.set_value(0);
ColPartitionGridSearch gsearch(part_grid_);
ColPartition *part = NULL;
gsearch.StartFullSearch();
while ((part = gsearch.NextFullSearch()) != NULL) {
if (!IsTextOrEquationType(part->type())) {
continue;
}
IdentifyBlobsToSkip(part);
BLOBNBOX_C_IT bbox_it(part->boxes());
// Compute the height threshold.
GenericVector<int> blob_heights;
for (bbox_it.mark_cycle_pt (); !bbox_it.cycled_list();
bbox_it.forward()) {
if (bbox_it.data()->special_text_type() != BSTT_SKIP) {
blob_heights.push_back(bbox_it.data()->bounding_box().height());
}
}
blob_heights.sort();
int height_th = blob_heights[blob_heights.size() / 2] / 3 * 2;
for (bbox_it.mark_cycle_pt (); !bbox_it.cycled_list();
bbox_it.forward()) {
if (bbox_it.data()->special_text_type() != BSTT_SKIP) {
IdentifySpecialText(bbox_it.data(), height_th);
}
}
}
// Set the multiplier values back.
lang_tesseract_->classify_class_pruner_multiplier.set_value(
classify_class_pruner);
lang_tesseract_->classify_integer_matcher_multiplier.set_value(
classify_integer_matcher);
if (equationdetect_save_spt_image) { // For debug.
STRING outfile;
GetOutputTiffName("_spt", &outfile);
PaintSpecialTexts(outfile);
}
}
void EquationDetect::IdentifyBlobsToSkip(ColPartition* part) {
ASSERT_HOST(part);
BLOBNBOX_C_IT blob_it(part->boxes());
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
// At this moment, no blob should have been joined.
ASSERT_HOST(!blob_it.data()->joined_to_prev());
}
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
BLOBNBOX* blob = blob_it.data();
if (blob->joined_to_prev() || blob->special_text_type() == BSTT_SKIP) {
continue;
}
TBOX blob_box = blob->bounding_box();
// Search if any blob can be merged into blob. If found, then we mark all
// these blobs as BSTT_SKIP.
BLOBNBOX_C_IT blob_it2 = blob_it;
bool found = false;
while (!blob_it2.at_last()) {
BLOBNBOX* nextblob = blob_it2.forward();
const TBOX& nextblob_box = nextblob->bounding_box();
if (nextblob_box.left() >= blob_box.right()) {
break;
}
const float kWidthR = 0.4, kHeightR = 0.3;
bool xoverlap = blob_box.major_x_overlap(nextblob_box),
yoverlap = blob_box.y_overlap(nextblob_box);
float widthR = static_cast<float>(
MIN(nextblob_box.width(), blob_box.width())) /
MAX(nextblob_box.width(), blob_box.width());
float heightR = static_cast<float>(
MIN(nextblob_box.height(), blob_box.height())) /
MAX(nextblob_box.height(), blob_box.height());
if (xoverlap && yoverlap && widthR > kWidthR && heightR > kHeightR) {
// Found one, set nextblob type and recompute blob_box.
found = true;
nextblob->set_special_text_type(BSTT_SKIP);
blob_box += nextblob_box;
}
}
if (found) {
blob->set_special_text_type(BSTT_SKIP);
}
}
}
int EquationDetect::FindEquationParts(
ColPartitionGrid* part_grid, ColPartitionSet** best_columns) {
if (!equ_tesseract_ || !lang_tesseract_) {
tprintf("Warning: equ_tesseract_/lang_tesseract_ is NULL!\n");
return -1;
}
if (!part_grid || !best_columns) {
tprintf("part_grid/best_columns is NULL!!\n");
return -1;
}
cp_seeds_.clear();
part_grid_ = part_grid;
best_columns_ = best_columns;
resolution_ = lang_tesseract_->source_resolution();
STRING outfile;
page_count_++;
if (equationdetect_save_bi_image) {
GetOutputTiffName("_bi", &outfile);
pixWrite(outfile.string(), lang_tesseract_->pix_binary(), IFF_TIFF_G4);
}
// Pass 0: Compute special text type for blobs.
IdentifySpecialText();
// Pass 1: Merge parts by overlap.
MergePartsByLocation();
// Pass 2: compute the math blob density and find the seed partition.
IdentifySeedParts();
// We still need separate seed into block seed and inline seed partition.
IdentifyInlineParts();
if (equationdetect_save_seed_image) {
GetOutputTiffName("_seed", &outfile);
PaintColParts(outfile);
}
// Pass 3: expand block equation seeds.
while (!cp_seeds_.empty()) {
GenericVector<ColPartition*> seeds_expanded;
for (int i = 0; i < cp_seeds_.size(); ++i) {
if (ExpandSeed(cp_seeds_[i])) {
// If this seed is expanded, then we add it into seeds_expanded. Note
// this seed has been removed from part_grid_ if it is expanded.
seeds_expanded.push_back(cp_seeds_[i]);
}
}
// Add seeds_expanded back into part_grid_ and reset cp_seeds_.
for (int i = 0; i < seeds_expanded.size(); ++i) {
InsertPartAfterAbsorb(seeds_expanded[i]);
}
cp_seeds_ = seeds_expanded;
}
// Pass 4: find math block satellite text partitions and merge them.
ProcessMathBlockSatelliteParts();
if (equationdetect_save_merged_image) { // For debug.
GetOutputTiffName("_merged", &outfile);
PaintColParts(outfile);
}
return 0;
}
void EquationDetect::MergePartsByLocation() {
while (true) {
ColPartition* part = NULL;
// partitions that have been updated.
GenericVector<ColPartition*> parts_updated;
ColPartitionGridSearch gsearch(part_grid_);
gsearch.StartFullSearch();
while ((part = gsearch.NextFullSearch()) != NULL) {
if (!IsTextOrEquationType(part->type())) {
continue;
}
GenericVector<ColPartition*> parts_to_merge;
SearchByOverlap(part, &parts_to_merge);
if (parts_to_merge.empty()) {
continue;
}
// Merge parts_to_merge with part, and remove them from part_grid_.
part_grid_->RemoveBBox(part);
for (int i = 0; i < parts_to_merge.size(); ++i) {
ASSERT_HOST(parts_to_merge[i] != NULL && parts_to_merge[i] != part);
part->Absorb(parts_to_merge[i], NULL);
}
gsearch.RepositionIterator();
parts_updated.push_back(part);
}
if (parts_updated.empty()) { // Exit the loop
break;
}
// Re-insert parts_updated into part_grid_.
for (int i = 0; i < parts_updated.size(); ++i) {
InsertPartAfterAbsorb(parts_updated[i]);
}
}
}
void EquationDetect::SearchByOverlap(
ColPartition* seed,
GenericVector<ColPartition*>* parts_overlap) {
ASSERT_HOST(seed != NULL && parts_overlap != NULL);
if (!IsTextOrEquationType(seed->type())) {
return;
}
ColPartitionGridSearch search(part_grid_);
const TBOX& seed_box(seed->bounding_box());
const int kRadNeighborCells = 30;
search.StartRadSearch((seed_box.left() + seed_box.right()) / 2,
(seed_box.top() + seed_box.bottom()) / 2,
kRadNeighborCells);
search.SetUniqueMode(true);
// Search iteratively.
ColPartition *part;
GenericVector<ColPartition*> parts;
const float kLargeOverlapTh = 0.95;
const float kEquXOverlap = 0.4, kEquYOverlap = 0.5;
while ((part = search.NextRadSearch()) != NULL) {
if (part == seed || !IsTextOrEquationType(part->type())) {
continue;
}
const TBOX& part_box(part->bounding_box());
bool merge = false;
float x_overlap_fraction = part_box.x_overlap_fraction(seed_box),
y_overlap_fraction = part_box.y_overlap_fraction(seed_box);
// If part is large overlapped with seed, then set merge to true.
if (x_overlap_fraction >= kLargeOverlapTh &&
y_overlap_fraction >= kLargeOverlapTh) {
merge = true;
} else if (seed->type() == PT_EQUATION &&
IsTextOrEquationType(part->type())) {
if ((x_overlap_fraction > kEquXOverlap && y_overlap_fraction > 0.0) ||
(x_overlap_fraction > 0.0 && y_overlap_fraction > kEquYOverlap)) {
merge = true;
}
}
if (merge) { // Remove the part from search and put it into parts.
search.RemoveBBox();
parts_overlap->push_back(part);
}
}
}
void EquationDetect::InsertPartAfterAbsorb(ColPartition* part) {
ASSERT_HOST(part);
// Before insert part back into part_grid_, we will need re-compute some
// of its attributes such as first_column_, last_column_. However, we still
// want to preserve its type.
BlobTextFlowType flow_type = part->flow();
PolyBlockType part_type = part->type();
BlobRegionType blob_type = part->blob_type();
// Call SetPartitionType to re-compute the attributes of part.
const TBOX& part_box(part->bounding_box());
int grid_x, grid_y;
part_grid_->GridCoords(
part_box.left(), part_box.bottom(), &grid_x, &grid_y);
part->SetPartitionType(resolution_, best_columns_[grid_y]);
// Reset the types back.
part->set_type(part_type);
part->set_blob_type(blob_type);
part->set_flow(flow_type);
part->SetBlobTypes();
// Insert into part_grid_.
part_grid_->InsertBBox(true, true, part);
}
void EquationDetect::IdentifySeedParts() {
ColPartitionGridSearch gsearch(part_grid_);
ColPartition *part = NULL;
gsearch.StartFullSearch();
GenericVector<ColPartition*> seeds1, seeds2;
// The left coordinates of indented text partitions.
GenericVector<int> indented_texts_left;
// The foreground density of text partitions.
GenericVector<float> texts_foreground_density;
while ((part = gsearch.NextFullSearch()) != NULL) {
if (!IsTextOrEquationType(part->type())) {
continue;
}
part->ComputeSpecialBlobsDensity();
bool blobs_check = CheckSeedBlobsCount(part);
const int kTextBlobsTh = 20;
if (CheckSeedDensity(kMathDigitDensityTh1, kMathDigitDensityTh2, part) &&
blobs_check) {
// Passed high density threshold test, save into seeds1.
seeds1.push_back(part);
} else {
IndentType indent = IsIndented(part);
if (IsLeftIndented(indent) && blobs_check &&
CheckSeedDensity(kMathDigitDensityTh2, kMathDigitDensityTh2, part)) {
// Passed low density threshold test and is indented, save into seeds2.
seeds2.push_back(part);
} else if (!IsRightIndented(indent) &&
part->boxes_count() > kTextBlobsTh) {
// This is likely to be a text part, save the features.
const TBOX&box = part->bounding_box();
if (IsLeftIndented(indent)) {
indented_texts_left.push_back(box.left());
}
texts_foreground_density.push_back(ComputeForegroundDensity(box));
}
}
}
// Sort the features collected from text regions.
indented_texts_left.sort();
texts_foreground_density.sort();
float foreground_density_th = 0.15; // Default value.
if (!texts_foreground_density.empty()) {
// Use the median of the texts_foreground_density.
foreground_density_th = 0.8 * texts_foreground_density[
texts_foreground_density.size() / 2];
}
for (int i = 0; i < seeds1.size(); ++i) {
const TBOX& box = seeds1[i]->bounding_box();
if (CheckSeedFgDensity(foreground_density_th, seeds1[i]) &&
!(IsLeftIndented(IsIndented(seeds1[i])) &&
CountAlignment(indented_texts_left, box.left()) >=
kLeftIndentAlignmentCountTh)) {
// Mark as PT_EQUATION type.
seeds1[i]->set_type(PT_EQUATION);
cp_seeds_.push_back(seeds1[i]);
} else { // Mark as PT_INLINE_EQUATION type.
seeds1[i]->set_type(PT_INLINE_EQUATION);
}
}
for (int i = 0; i < seeds2.size(); ++i) {
if (CheckForSeed2(indented_texts_left, foreground_density_th, seeds2[i])) {
seeds2[i]->set_type(PT_EQUATION);
cp_seeds_.push_back(seeds2[i]);
}
}
}
float EquationDetect::ComputeForegroundDensity(const TBOX& tbox) {
#if LIBLEPT_MINOR_VERSION < 69 && LIBLEPT_MAJOR_VERSION <= 1
// This will disable the detector because no seed will be identified.
return 1.0f;
#else
Pix *pix_bi = lang_tesseract_->pix_binary();
int pix_height = pixGetHeight(pix_bi);
Box* box = boxCreate(tbox.left(), pix_height - tbox.top(),
tbox.width(), tbox.height());
Pix *pix_sub = pixClipRectangle(pix_bi, box, NULL);
l_float32 fract;
pixForegroundFraction(pix_sub, &fract);
pixDestroy(&pix_sub);
boxDestroy(&box);
return fract;
#endif
}
bool EquationDetect::CheckSeedFgDensity(const float density_th,
ColPartition* part) {
ASSERT_HOST(part);
// Split part horizontall, and check for each sub part.
GenericVector<TBOX> sub_boxes;
SplitCPHorLite(part, &sub_boxes);
float parts_passed = 0.0;
for (int i = 0; i < sub_boxes.size(); ++i) {
float density = ComputeForegroundDensity(sub_boxes[i]);
if (density < density_th) {
parts_passed++;
}
}
// If most sub parts passed, then we return true.
const float kSeedPartRatioTh = 0.3;
bool retval = (parts_passed / sub_boxes.size() >= kSeedPartRatioTh);
return retval;
}
void EquationDetect::SplitCPHor(ColPartition* part,
GenericVector<ColPartition*>* parts_splitted) {
ASSERT_HOST(part && parts_splitted);
if (part->median_width() == 0 || part->boxes_count() == 0) {
return;
}
// Make a copy of part, and reset parts_splitted.
ColPartition* right_part = part->CopyButDontOwnBlobs();
parts_splitted->delete_data_pointers();
parts_splitted->clear();
const double kThreshold = part->median_width() * 3.0;
bool found_split = true;
while (found_split) {
found_split = false;
BLOBNBOX_C_IT box_it(right_part->boxes());
// Blobs are sorted left side first. If blobs overlap,
// the previous blob may have a "more right" right side.
// Account for this by always keeping the largest "right"
// so far.
int previous_right = MIN_INT32;
// Look for the next split in the partition.
for (box_it.mark_cycle_pt(); !box_it.cycled_list(); box_it.forward()) {
const TBOX& box = box_it.data()->bounding_box();
if (previous_right != MIN_INT32 &&
box.left() - previous_right > kThreshold) {
// We have a split position. Split the partition in two pieces.
// Insert the left piece in the grid and keep processing the right.
int mid_x = (box.left() + previous_right) / 2;
ColPartition* left_part = right_part;
right_part = left_part->SplitAt(mid_x);
parts_splitted->push_back(left_part);
left_part->ComputeSpecialBlobsDensity();
found_split = true;
break;
}
// The right side of the previous blobs.
previous_right = MAX(previous_right, box.right());
}
}
// Add the last piece.
right_part->ComputeSpecialBlobsDensity();
parts_splitted->push_back(right_part);
}
void EquationDetect::SplitCPHorLite(ColPartition* part,
GenericVector<TBOX>* splitted_boxes) {
ASSERT_HOST(part && splitted_boxes);
splitted_boxes->clear();
if (part->median_width() == 0) {
return;
}
const double kThreshold = part->median_width() * 3.0;
// Blobs are sorted left side first. If blobs overlap,
// the previous blob may have a "more right" right side.
// Account for this by always keeping the largest "right"
// so far.
TBOX union_box;
int previous_right = MIN_INT32;
BLOBNBOX_C_IT box_it(part->boxes());
for (box_it.mark_cycle_pt(); !box_it.cycled_list(); box_it.forward()) {
const TBOX& box = box_it.data()->bounding_box();
if (previous_right != MIN_INT32 &&
box.left() - previous_right > kThreshold) {
// We have a split position.
splitted_boxes->push_back(union_box);
previous_right = MIN_INT32;
}
if (previous_right == MIN_INT32) {
union_box = box;
} else {
union_box += box;
}
// The right side of the previous blobs.
previous_right = MAX(previous_right, box.right());
}
// Add the last piece.
if (previous_right != MIN_INT32) {
splitted_boxes->push_back(union_box);
}
}
bool EquationDetect::CheckForSeed2(
const GenericVector<int>& indented_texts_left,
const float foreground_density_th,
ColPartition* part) {
ASSERT_HOST(part);
const TBOX& box = part->bounding_box();
// Check if it is aligned with any indented_texts_left.
if (!indented_texts_left.empty() &&
CountAlignment(indented_texts_left, box.left()) >=
kLeftIndentAlignmentCountTh) {
return false;
}
// Check the foreground density.
if (ComputeForegroundDensity(box) > foreground_density_th) {
return false;
}
return true;
}
int EquationDetect::CountAlignment(
const GenericVector<int>& sorted_vec, const int val) const {
if (sorted_vec.empty()) {
return 0;
}
const int kDistTh = static_cast<int>(roundf(0.03 * resolution_));
int pos = sorted_vec.binary_search(val), count = 0;
// Search left side.
int index = pos;
while (index >= 0 && abs(val - sorted_vec[index--]) < kDistTh) {
count++;
}
// Search right side.
index = pos + 1;
while (index < sorted_vec.size() && sorted_vec[index++] - val < kDistTh) {
count++;
}
return count;
}
void EquationDetect::IdentifyInlineParts() {
ComputeCPsSuperBBox();
IdentifyInlinePartsHorizontal();
int textparts_linespacing = EstimateTextPartLineSpacing();
IdentifyInlinePartsVertical(true, textparts_linespacing);
IdentifyInlinePartsVertical(false, textparts_linespacing);
}
void EquationDetect::ComputeCPsSuperBBox() {
ColPartitionGridSearch gsearch(part_grid_);
ColPartition *part = NULL;
gsearch.StartFullSearch();
if (cps_super_bbox_) {
delete cps_super_bbox_;
}
cps_super_bbox_ = new TBOX();
while ((part = gsearch.NextFullSearch()) != NULL) {
(*cps_super_bbox_) += part->bounding_box();
}
}
void EquationDetect::IdentifyInlinePartsHorizontal() {
ASSERT_HOST(cps_super_bbox_);
GenericVector<ColPartition*> new_seeds;
const int kMarginDiffTh = IntCastRounded(
0.5 * lang_tesseract_->source_resolution());
const int kGapTh = static_cast<int>(roundf(
1.0 * lang_tesseract_->source_resolution()));
ColPartitionGridSearch search(part_grid_);
search.SetUniqueMode(true);
// The center x coordinate of the cp_super_bbox_.
int cps_cx = cps_super_bbox_->left() + cps_super_bbox_->width() / 2;
for (int i = 0; i < cp_seeds_.size(); ++i) {
ColPartition* part = cp_seeds_[i];
const TBOX& part_box(part->bounding_box());
int left_margin = part_box.left() - cps_super_bbox_->left(),
right_margin = cps_super_bbox_->right() - part_box.right();
bool right_to_left;
if (left_margin + kMarginDiffTh < right_margin &&
left_margin < kMarginDiffTh) {
// part is left aligned, so we search if it has any right neighbor.
search.StartSideSearch(
part_box.right(), part_box.top(), part_box.bottom());
right_to_left = false;
} else if (left_margin > cps_cx) {
// part locates on the right half on image, so search if it has any left
// neighbor.
search.StartSideSearch(
part_box.left(), part_box.top(), part_box.bottom());
right_to_left = true;
} else { // part is not an inline equation.
new_seeds.push_back(part);
continue;
}
ColPartition* neighbor = NULL;
bool side_neighbor_found = false;
while ((neighbor = search.NextSideSearch(right_to_left)) != NULL) {
const TBOX& neighbor_box(neighbor->bounding_box());
if (!IsTextOrEquationType(neighbor->type()) ||
part_box.x_gap(neighbor_box) > kGapTh ||
!part_box.major_y_overlap(neighbor_box) ||
part_box.major_x_overlap(neighbor_box)) {
continue;
}
// We have found one. Set the side_neighbor_found flag.
side_neighbor_found = true;
break;
}
if (!side_neighbor_found) { // Mark part as PT_INLINE_EQUATION.
part->set_type(PT_INLINE_EQUATION);
} else {
// Check the geometric feature of neighbor.
const TBOX& neighbor_box(neighbor->bounding_box());
if (neighbor_box.width() > part_box.width() &&
neighbor->type() != PT_EQUATION) { // Mark as PT_INLINE_EQUATION.
part->set_type(PT_INLINE_EQUATION);
} else { // part is not an inline equation type.
new_seeds.push_back(part);
}
}
}
// Reset the cp_seeds_ using the new_seeds.
cp_seeds_ = new_seeds;
}
int EquationDetect::EstimateTextPartLineSpacing() {
ColPartitionGridSearch gsearch(part_grid_);
// Get the y gap between text partitions;
ColPartition *current = NULL, *prev = NULL;
gsearch.StartFullSearch();
GenericVector<int> ygaps;
while ((current = gsearch.NextFullSearch()) != NULL) {
if (!PTIsTextType(current->type())) {
continue;
}
if (prev != NULL) {
const TBOX &current_box = current->bounding_box();
const TBOX &prev_box = prev->bounding_box();
// prev and current should be x major overlap and non y overlap.
if (current_box.major_x_overlap(prev_box) &&
!current_box.y_overlap(prev_box)) {
int gap = current_box.y_gap(prev_box);
if (gap < MIN(current_box.height(), prev_box.height())) {
// The gap should be smaller than the height of the bounding boxes.
ygaps.push_back(gap);
}
}
}
prev = current;
}
if (ygaps.size() < 8) { // We do not have enough data.
return -1;
}
// Compute the line spacing from ygaps: use the mean of the first half.
ygaps.sort();
int spacing = 0, count;
for (count = 0; count < ygaps.size() / 2; count++) {
spacing += ygaps[count];
}
return spacing / count;
}
void EquationDetect::IdentifyInlinePartsVertical(
const bool top_to_bottom, const int textparts_linespacing) {
if (cp_seeds_.empty()) {
return;
}
// Sort cp_seeds_.
if (top_to_bottom) { // From top to bottom.
cp_seeds_.sort(&SortCPByTopReverse);
} else { // From bottom to top.
cp_seeds_.sort(&SortCPByBottom);
}
GenericVector<ColPartition*> new_seeds;
for (int i = 0; i < cp_seeds_.size(); ++i) {
ColPartition* part = cp_seeds_[i];
// If we sort cp_seeds_ from top to bottom, then for each cp_seeds_, we look
// for its top neighbors, so that if two/more inline regions are connected
// to each other, then we will identify the top one, and then use it to
// identify the bottom one.
if (IsInline(!top_to_bottom, textparts_linespacing, part)) {
part->set_type(PT_INLINE_EQUATION);
} else {
new_seeds.push_back(part);
}
}
cp_seeds_ = new_seeds;
}
bool EquationDetect::IsInline(const bool search_bottom,
const int textparts_linespacing,
ColPartition* part) {
ASSERT_HOST(part != NULL);
// Look for its nearest vertical neighbor that hardly overlaps in y but
// largely overlaps in x.
ColPartitionGridSearch search(part_grid_);
ColPartition *neighbor = NULL;
const TBOX& part_box(part->bounding_box());
const float kYGapRatioTh = 1.0;
if (search_bottom) {
search.StartVerticalSearch(part_box.left(), part_box.right(),
part_box.bottom());
} else {
search.StartVerticalSearch(part_box.left(), part_box.right(),
part_box.top());
}
search.SetUniqueMode(true);
while ((neighbor = search.NextVerticalSearch(search_bottom)) != NULL) {
const TBOX& neighbor_box(neighbor->bounding_box());
if (part_box.y_gap(neighbor_box) > kYGapRatioTh *
MIN(part_box.height(), neighbor_box.height())) {
// Finished searching.
break;
}
if (!PTIsTextType(neighbor->type())) {
continue;
}
// Check if neighbor and part is inline similar.
const float kHeightRatioTh = 0.5;
const int kYGapTh = textparts_linespacing > 0 ?
textparts_linespacing + static_cast<int>(roundf(0.02 * resolution_)):
static_cast<int>(roundf(0.05 * resolution_)); // Default value.
if (part_box.x_overlap(neighbor_box) && // Location feature.
part_box.y_gap(neighbor_box) <= kYGapTh && // Line spacing.
// Geo feature.
static_cast<float>(MIN(part_box.height(), neighbor_box.height())) /
MAX(part_box.height(), neighbor_box.height()) > kHeightRatioTh) {
return true;
}
}
return false;
}
bool EquationDetect::CheckSeedBlobsCount(ColPartition* part) {
if (!part) {
return false;
}
const int kSeedMathBlobsCount = 2;
const int kSeedMathDigitBlobsCount = 5;
int blobs = part->boxes_count(),
math_blobs = part->SpecialBlobsCount(BSTT_MATH),
digit_blobs = part->SpecialBlobsCount(BSTT_DIGIT);
if (blobs < kSeedBlobsCountTh || math_blobs <= kSeedMathBlobsCount ||
math_blobs + digit_blobs <= kSeedMathDigitBlobsCount) {
return false;
}
return true;
}
bool EquationDetect::CheckSeedDensity(
const float math_density_high,
const float math_density_low,
const ColPartition* part) const {
ASSERT_HOST(part);
float math_digit_density = part->SpecialBlobsDensity(BSTT_MATH)
+ part->SpecialBlobsDensity(BSTT_DIGIT);
float italic_density = part->SpecialBlobsDensity(BSTT_ITALIC);
if (math_digit_density > math_density_high) {
return true;
}
if (math_digit_density + italic_density > kMathItalicDensityTh &&
math_digit_density > math_density_low) {
return true;
}
return false;
}
EquationDetect::IndentType EquationDetect::IsIndented(ColPartition* part) {
ASSERT_HOST(part);
ColPartitionGridSearch search(part_grid_);
ColPartition *neighbor = NULL;
const TBOX& part_box(part->bounding_box());
const int kXGapTh = static_cast<int>(roundf(0.5 * resolution_));
const int kRadiusTh = static_cast<int>(roundf(3.0 * resolution_));
const int kYGapTh = static_cast<int>(roundf(0.5 * resolution_));
// Here we use a simple approximation algorithm: from the center of part, We
// perform the radius search, and check if we can find a neighboring parition
// that locates on the top/bottom left of part.
search.StartRadSearch((part_box.left() + part_box.right()) / 2,
(part_box.top() + part_box.bottom()) / 2, kRadiusTh);
search.SetUniqueMode(true);
bool left_indented = false, right_indented = false;
while ((neighbor = search.NextRadSearch()) != NULL &&
(!left_indented || !right_indented)) {
if (neighbor == part) {
continue;
}
const TBOX& neighbor_box(neighbor->bounding_box());
if (part_box.major_y_overlap(neighbor_box) &&
part_box.x_gap(neighbor_box) < kXGapTh) {
// When this happens, it is likely part is a fragment of an
// over-segmented colpartition. So we return false.
return NO_INDENT;
}
if (!IsTextOrEquationType(neighbor->type())) {
continue;
}
// The neighbor should be above/below part, and overlap in x direction.
if (!part_box.x_overlap(neighbor_box) || part_box.y_overlap(neighbor_box)) {
continue;
}
if (part_box.y_gap(neighbor_box) < kYGapTh) {
int left_gap = part_box.left() - neighbor_box.left();
int right_gap = neighbor_box.right() - part_box.right();
if (left_gap > kXGapTh) {
left_indented = true;
}
if (right_gap > kXGapTh) {
right_indented = true;
}
}
}
if (left_indented && right_indented) {
return BOTH_INDENT;
}
if (left_indented) {
return LEFT_INDENT;
}
if (right_indented) {
return RIGHT_INDENT;
}
return NO_INDENT;
}
bool EquationDetect::ExpandSeed(ColPartition* seed) {
if (seed == NULL || // This seed has been absorbed by other seeds.
seed->IsVerticalType()) { // We skip vertical type right now.
return false;
}
// Expand in four directions.
GenericVector<ColPartition*> parts_to_merge;
ExpandSeedHorizontal(true, seed, &parts_to_merge);
ExpandSeedHorizontal(false, seed, &parts_to_merge);
ExpandSeedVertical(true, seed, &parts_to_merge);
ExpandSeedVertical(false, seed, &parts_to_merge);
SearchByOverlap(seed, &parts_to_merge);
if (parts_to_merge.empty()) { // We don't find any partition to merge.
return false;
}
// Merge all partitions in parts_to_merge with seed. We first remove seed
// from part_grid_ as its bounding box is going to expand. Then we add it
// back after it aborbs all parts_to_merge parititions.
part_grid_->RemoveBBox(seed);
for (int i = 0; i < parts_to_merge.size(); ++i) {
ColPartition* part = parts_to_merge[i];
if (part->type() == PT_EQUATION) {
// If part is in cp_seeds_, then we mark it as NULL so that we won't
// process it again.
for (int j = 0; j < cp_seeds_.size(); ++j) {
if (part == cp_seeds_[j]) {
cp_seeds_[j] = NULL;
break;
}
}
}
// part has already been removed from part_grid_ in function
// ExpandSeedHorizontal/ExpandSeedVertical.
seed->Absorb(part, NULL);
}
return true;
}
void EquationDetect::ExpandSeedHorizontal(
const bool search_left,
ColPartition* seed,
GenericVector<ColPartition*>* parts_to_merge) {
ASSERT_HOST(seed != NULL && parts_to_merge != NULL);
const float kYOverlapTh = 0.6;
const int kXGapTh = static_cast<int>(roundf(0.2 * resolution_));
ColPartitionGridSearch search(part_grid_);
const TBOX& seed_box(seed->bounding_box());
int x = search_left ? seed_box.left() : seed_box.right();
search.StartSideSearch(x, seed_box.bottom(), seed_box.top());
search.SetUniqueMode(true);
// Search iteratively.
ColPartition *part = NULL;
while ((part = search.NextSideSearch(search_left)) != NULL) {
if (part == seed) {
continue;
}
const TBOX& part_box(part->bounding_box());
if (part_box.x_gap(seed_box) > kXGapTh) { // Out of scope.
break;
}
// Check part location.
if ((part_box.left() >= seed_box.left() && search_left) ||
(part_box.right() <= seed_box.right() && !search_left)) {
continue;
}
if (part->type() != PT_EQUATION) { // Non-equation type.
// Skip PT_LINLINE_EQUATION and non text type.
if (part->type() == PT_INLINE_EQUATION ||
(!IsTextOrEquationType(part->type()) &&
part->blob_type() != BRT_HLINE)) {
continue;
}
// For other types, it should be the near small neighbor of seed.
if (!IsNearSmallNeighbor(seed_box, part_box) ||
!CheckSeedNeighborDensity(part)) {
continue;
}
} else { // Equation type, check the y overlap.
if (part_box.y_overlap_fraction(seed_box) < kYOverlapTh &&
seed_box.y_overlap_fraction(part_box) < kYOverlapTh) {
continue;
}
}
// Passed the check, delete it from search and add into parts_to_merge.
search.RemoveBBox();
parts_to_merge->push_back(part);
}
}
void EquationDetect::ExpandSeedVertical(
const bool search_bottom,
ColPartition* seed,
GenericVector<ColPartition*>* parts_to_merge) {
ASSERT_HOST(seed != NULL && parts_to_merge != NULL &&
cps_super_bbox_ != NULL);
const float kXOverlapTh = 0.4;
const int kYGapTh = static_cast<int>(roundf(0.2 * resolution_));
ColPartitionGridSearch search(part_grid_);
const TBOX& seed_box(seed->bounding_box());
int y = search_bottom ? seed_box.bottom() : seed_box.top();
search.StartVerticalSearch(
cps_super_bbox_->left(), cps_super_bbox_->right(), y);
search.SetUniqueMode(true);
// Search iteratively.
ColPartition *part = NULL;
GenericVector<ColPartition*> parts;
int skipped_min_top = INT_MAX, skipped_max_bottom = -1;
while ((part = search.NextVerticalSearch(search_bottom)) != NULL) {
if (part == seed) {
continue;
}
const TBOX& part_box(part->bounding_box());
if (part_box.y_gap(seed_box) > kYGapTh) { // Out of scope.
break;
}
// Check part location.
if ((part_box.bottom() >= seed_box.bottom() && search_bottom) ||
(part_box.top() <= seed_box.top() && !search_bottom)) {
continue;
}
bool skip_part = false;
if (part->type() != PT_EQUATION) { // Non-equation type.
// Skip PT_LINLINE_EQUATION and non text type.
if (part->type() == PT_INLINE_EQUATION ||
(!IsTextOrEquationType(part->type()) &&
part->blob_type() != BRT_HLINE)) {
skip_part = true;
} else if (!IsNearSmallNeighbor(seed_box, part_box) ||
!CheckSeedNeighborDensity(part)) {
// For other types, it should be the near small neighbor of seed.
skip_part = true;
}
} else { // Equation type, check the x overlap.
if (part_box.x_overlap_fraction(seed_box) < kXOverlapTh &&
seed_box.x_overlap_fraction(part_box) < kXOverlapTh) {
skip_part = true;
}
}
if (skip_part) {
if (part->type() != PT_EQUATION) {
if (skipped_min_top > part_box.top()) {
skipped_min_top = part_box.top();
}
if (skipped_max_bottom < part_box.bottom()) {
skipped_max_bottom = part_box.bottom();
}
}
} else {
parts.push_back(part);
}
}
// For every part in parts, we need verify it is not above skipped_min_top
// when search top, or not below skipped_max_bottom when search bottom. I.e.,
// we will skip a part if it looks like:
// search bottom | search top
// seed: ****************** | part: **********
// skipped: xxx | skipped: xxx
// part: ********** | seed: ***********
for (int i = 0; i < parts.size(); i++) {
const TBOX& part_box(parts[i]->bounding_box());
if ((search_bottom && part_box.top() <= skipped_max_bottom) ||
(!search_bottom && part_box.bottom() >= skipped_min_top)) {
continue;
}
// Add parts[i] into parts_to_merge, and delete it from part_grid_.
parts_to_merge->push_back(parts[i]);
part_grid_->RemoveBBox(parts[i]);
}
}
bool EquationDetect::IsNearSmallNeighbor(const TBOX& seed_box,
const TBOX& part_box) const {
const int kXGapTh = static_cast<int>(roundf(0.25 * resolution_));
const int kYGapTh = static_cast<int>(roundf(0.05 * resolution_));
// Check geometric feature.
if (part_box.height() > seed_box.height() ||
part_box.width() > seed_box.width()) {
return false;
}
// Check overlap and distance.
if ((!part_box.major_x_overlap(seed_box) ||
part_box.y_gap(seed_box) > kYGapTh) &&
(!part_box.major_y_overlap(seed_box) ||
part_box.x_gap(seed_box) > kXGapTh)) {
return false;
}
return true;
}
bool EquationDetect::CheckSeedNeighborDensity(const ColPartition* part) const {
ASSERT_HOST(part);
if (part->boxes_count() < kSeedBlobsCountTh) {
// Too few blobs, skip the check.
return true;
}
// We check the math blobs density and the unclear blobs density.
if (part->SpecialBlobsDensity(BSTT_MATH) +
part->SpecialBlobsDensity(BSTT_DIGIT) > kMathDigitDensityTh1 ||
part->SpecialBlobsDensity(BSTT_UNCLEAR) > kUnclearDensityTh) {
return true;
}
return false;
}
void EquationDetect::ProcessMathBlockSatelliteParts() {
// Iterate over part_grid_, and find all parts that are text type but not
// equation type.
ColPartition *part = NULL;
GenericVector<ColPartition*> text_parts;
ColPartitionGridSearch gsearch(part_grid_);
gsearch.StartFullSearch();
while ((part = gsearch.NextFullSearch()) != NULL) {
if (part->type() == PT_FLOWING_TEXT || part->type() == PT_HEADING_TEXT) {
text_parts.push_back(part);
}
}
if (text_parts.empty()) {
return;
}
// Compute the medium height of the text_parts.
text_parts.sort(&SortCPByHeight);
const TBOX& text_box = text_parts[text_parts.size() / 2]->bounding_box();
int med_height = text_box.height();
if (text_parts.size() % 2 == 0 && text_parts.size() > 1) {
const TBOX& text_box =
text_parts[text_parts.size() / 2 - 1]->bounding_box();
med_height = static_cast<int>(roundf(
0.5 * (text_box.height() + med_height)));
}
// Iterate every text_parts and check if it is a math block satellite.
for (int i = 0; i < text_parts.size(); ++i) {
const TBOX& text_box(text_parts[i]->bounding_box());
if (text_box.height() > med_height) {
continue;
}
GenericVector<ColPartition*> math_blocks;
if (!IsMathBlockSatellite(text_parts[i], &math_blocks)) {
continue;
}
// Found. merge text_parts[i] with math_blocks.
part_grid_->RemoveBBox(text_parts[i]);
text_parts[i]->set_type(PT_EQUATION);
for (int j = 0; j < math_blocks.size(); ++j) {
part_grid_->RemoveBBox(math_blocks[j]);
text_parts[i]->Absorb(math_blocks[j], NULL);
}
InsertPartAfterAbsorb(text_parts[i]);
}
}
bool EquationDetect::IsMathBlockSatellite(
ColPartition* part, GenericVector<ColPartition*>* math_blocks) {
ASSERT_HOST(part != NULL && math_blocks != NULL);
math_blocks->clear();
const TBOX& part_box(part->bounding_box());
// Find the top/bottom nearest neighbor of part.
ColPartition *neighbors[2];
int y_gaps[2] = {INT_MAX, INT_MAX};
// The horizontal boundary of the neighbors.
int neighbors_left = INT_MAX, neighbors_right = 0;
for (int i = 0; i < 2; ++i) {
neighbors[i] = SearchNNVertical(i != 0, part);
if (neighbors[i]) {
const TBOX& neighbor_box = neighbors[i]->bounding_box();
y_gaps[i] = neighbor_box.y_gap(part_box);
if (neighbor_box.left() < neighbors_left) {
neighbors_left = neighbor_box.left();
}
if (neighbor_box.right() > neighbors_right) {
neighbors_right = neighbor_box.right();
}
}
}
if (neighbors[0] == neighbors[1]) {
// This happens when part is inside neighbor.
neighbors[1] = NULL;
y_gaps[1] = INT_MAX;
}
// Check if part is within [neighbors_left, neighbors_right].
if (part_box.left() < neighbors_left || part_box.right() > neighbors_right) {
return false;
}
// Get the index of the near one in neighbors.
int index = y_gaps[0] < y_gaps[1] ? 0 : 1;
// Check the near one.
if (IsNearMathNeighbor(y_gaps[index], neighbors[index])) {
math_blocks->push_back(neighbors[index]);
} else {
// If the near one failed the check, then we skip checking the far one.
return false;
}
// Check the far one.
index = 1 - index;
if (IsNearMathNeighbor(y_gaps[index], neighbors[index])) {
math_blocks->push_back(neighbors[index]);
}
return true;
}
ColPartition* EquationDetect::SearchNNVertical(
const bool search_bottom, const ColPartition* part) {
ASSERT_HOST(part);
ColPartition *nearest_neighbor = NULL, *neighbor = NULL;
const int kYGapTh = static_cast<int>(roundf(resolution_ * 0.5));
ColPartitionGridSearch search(part_grid_);
search.SetUniqueMode(true);
const TBOX& part_box(part->bounding_box());
int y = search_bottom ? part_box.bottom() : part_box.top();
search.StartVerticalSearch(part_box.left(), part_box.right(), y);
int min_y_gap = INT_MAX;
while ((neighbor = search.NextVerticalSearch(search_bottom)) != NULL) {
if (neighbor == part || !IsTextOrEquationType(neighbor->type())) {
continue;
}
const TBOX& neighbor_box(neighbor->bounding_box());
int y_gap = neighbor_box.y_gap(part_box);
if (y_gap > kYGapTh) { // Out of scope.
break;
}
if (!neighbor_box.major_x_overlap(part_box) ||
(search_bottom && neighbor_box.bottom() > part_box.bottom()) ||
(!search_bottom && neighbor_box.top() < part_box.top())) {
continue;
}
if (y_gap < min_y_gap) {
min_y_gap = y_gap;
nearest_neighbor = neighbor;
}
}
return nearest_neighbor;
}
bool EquationDetect::IsNearMathNeighbor(
const int y_gap, const ColPartition *neighbor) const {
if (!neighbor) {
return false;
}
const int kYGapTh = static_cast<int>(roundf(resolution_ * 0.1));
return neighbor->type() == PT_EQUATION && y_gap <= kYGapTh;
}
void EquationDetect::GetOutputTiffName(const char* name,
STRING* image_name) const {
ASSERT_HOST(image_name && name);
char page[50];
snprintf(page, sizeof(page), "%04d", page_count_);
*image_name = STRING(lang_tesseract_->imagebasename) + page + name + ".tif";
}
void EquationDetect::PaintSpecialTexts(const STRING& outfile) const {
Pix *pix = NULL, *pixBi = lang_tesseract_->pix_binary();
pix = pixConvertTo32(pixBi);
ColPartitionGridSearch gsearch(part_grid_);
ColPartition* part = NULL;
gsearch.StartFullSearch();
while ((part = gsearch.NextFullSearch()) != NULL) {
BLOBNBOX_C_IT blob_it(part->boxes());
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
RenderSpecialText(pix, blob_it.data());
}
}
pixWrite(outfile.string(), pix, IFF_TIFF_LZW);
pixDestroy(&pix);
}
void EquationDetect::PaintColParts(const STRING& outfile) const {
Pix *pix = pixConvertTo32(lang_tesseract_->BestPix());
ColPartitionGridSearch gsearch(part_grid_);
gsearch.StartFullSearch();
ColPartition* part = NULL;
while ((part = gsearch.NextFullSearch()) != NULL) {
const TBOX& tbox = part->bounding_box();
Box *box = boxCreate(tbox.left(), pixGetHeight(pix) - tbox.top(),
tbox.width(), tbox.height());
if (part->type() == PT_EQUATION) {
pixRenderBoxArb(pix, box, 5, 255, 0, 0);
} else if (part->type() == PT_INLINE_EQUATION) {
pixRenderBoxArb(pix, box, 5, 0, 255, 0);
} else {
pixRenderBoxArb(pix, box, 5, 0, 0, 255);
}
boxDestroy(&box);
}
pixWrite(outfile.string(), pix, IFF_TIFF_LZW);
pixDestroy(&pix);
}
void EquationDetect::PrintSpecialBlobsDensity(const ColPartition* part) const {
ASSERT_HOST(part);
TBOX box(part->bounding_box());
int h = pixGetHeight(lang_tesseract_->BestPix());
tprintf("Printing special blobs density values for ColParition (t=%d,b=%d) ",
h - box.top(), h - box.bottom());
box.print();
tprintf("blobs count = %d, density = ", part->boxes_count());
for (int i = 0; i < BSTT_COUNT; ++i) {
BlobSpecialTextType type = static_cast<BlobSpecialTextType>(i);
tprintf("%d:%f ", i, part->SpecialBlobsDensity(type));
}
tprintf("\n");
}
}; // namespace tesseract
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