#include <equationdetect.h>

Inheritance diagram for tesseract::EquationDetect:

Public Types
enum	IndentType { NO_INDENT, LEFT_INDENT, RIGHT_INDENT, BOTH_INDENT, INDENT_TYPE_COUNT }

Public Member Functions
	EquationDetect (const char equ_datapath, const char equ_language)

	~EquationDetect () override

void	SetLangTesseract (Tesseract *lang_tesseract)

int	LabelSpecialText (TO_BLOCK *to_block) override

int	FindEquationParts (ColPartitionGrid part_grid, ColPartitionSet *best_columns) override

void	SetResolution (const int resolution)

Public Member Functions inherited from tesseract::EquationDetectBase
	EquationDetectBase ()=default

virtual	~EquationDetectBase ()

Protected Member Functions
void	IdentifySpecialText (BLOBNBOX *blob, const int height_th)

BlobSpecialTextType	EstimateTypeForUnichar (const UNICHARSET &unicharset, const UNICHAR_ID id) const

void	IdentifySpecialText ()

void	IdentifyBlobsToSkip (ColPartition *part)

void	MergePartsByLocation ()

void	SearchByOverlap (ColPartition seed, GenericVector< ColPartition > *parts_overlap)

void	InsertPartAfterAbsorb (ColPartition *part)

void	IdentifySeedParts ()

bool	CheckSeedBlobsCount (ColPartition *part)

float	ComputeForegroundDensity (const TBOX &tbox)

bool	CheckForSeed2 (const GenericVector< int > &indented_texts_left, const float foreground_density_th, ColPartition *part)

int	CountAlignment (const GenericVector< int > &sorted_vec, const int val) const

bool	CheckSeedFgDensity (const float density_th, ColPartition *part)

void	SplitCPHorLite (ColPartition part, GenericVector< TBOX > splitted_boxes)

void	SplitCPHor (ColPartition part, GenericVector< ColPartition > *parts_splitted)

bool	CheckSeedDensity (const float math_density_high, const float math_density_low, const ColPartition *part) const

IndentType	IsIndented (ColPartition *part)

void	IdentifyInlineParts ()

void	ComputeCPsSuperBBox ()

void	IdentifyInlinePartsHorizontal ()

int	EstimateTextPartLineSpacing ()

void	IdentifyInlinePartsVertical (const bool top_to_bottom, const int textPartsLineSpacing)

bool	IsInline (const bool search_bottom, const int textPartsLineSpacing, ColPartition *part)

bool	ExpandSeed (ColPartition *seed)

void	ExpandSeedHorizontal (const bool search_left, ColPartition seed, GenericVector< ColPartition > *parts_to_merge)

void	ExpandSeedVertical (const bool search_bottom, ColPartition seed, GenericVector< ColPartition > *parts_to_merge)

bool	IsNearSmallNeighbor (const TBOX &seed_box, const TBOX &part_box) const

bool	CheckSeedNeighborDensity (const ColPartition *part) const

void	ProcessMathBlockSatelliteParts ()

bool	IsMathBlockSatellite (ColPartition part, GenericVector< ColPartition > *math_blocks)

ColPartition *	SearchNNVertical (const bool search_bottom, const ColPartition *part)

bool	IsNearMathNeighbor (const int y_gap, const ColPartition *neighbor) const

void	GetOutputTiffName (const char name, STRING image_name) const

void	PaintColParts (const STRING &outfile) const

void	PaintSpecialTexts (const STRING &outfile) const

void	PrintSpecialBlobsDensity (const ColPartition *part) const

Protected Attributes
Tesseract	equ_tesseract_

Tesseract *	lang_tesseract_

ColPartitionGrid *	part_grid_ = nullptr

ColPartitionSet **	best_columns_ = nullptr

TBOX *	cps_super_bbox_

GenericVector< ColPartition * >	cp_seeds_

int	resolution_

int	page_count_

Additional Inherited Members
Static Public Member Functions inherited from tesseract::EquationDetectBase
static void	RenderSpecialText (Pix pix, BLOBNBOX blob)

Detailed Description

Definition at line 38 of file equationdetect.h.

Member Enumeration Documentation

◆ IndentType

enum tesseract::EquationDetect::IndentType

Enumerator
NO_INDENT
LEFT_INDENT
RIGHT_INDENT
BOTH_INDENT
INDENT_TYPE_COUNT

Definition at line 44 of file equationdetect.h.

                   {
     NO_INDENT,
     LEFT_INDENT,
     RIGHT_INDENT,
     BOTH_INDENT,
     INDENT_TYPE_COUNT
   };

Constructor & Destructor Documentation

◆ EquationDetect()

tesseract::EquationDetect::EquationDetect	(	const char *	equ_datapath,
		const char *	equ_language
	)

Definition at line 102 of file equationdetect.cpp.

                                                      {
   const char* default_name = "equ";
   if (equ_name == nullptr) {
     equ_name = default_name;
   }
   lang_tesseract_ = nullptr;
   resolution_ = 0;
   page_count_ = 0;
  
   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);
   }
  
   cps_super_bbox_ = nullptr;
 }

◆ ~EquationDetect()

tesseract::EquationDetect::~EquationDetect ( )

override

Definition at line 121 of file equationdetect.cpp.

121 { delete (cps_super_bbox_); }

Member Function Documentation

◆ CheckForSeed2()

bool tesseract::EquationDetect::CheckForSeed2	(	const GenericVector< int > &	indented_texts_left,
		const float	foreground_density_th,
		ColPartition *	part
	)

protected

Definition at line 737 of file equationdetect.cpp.

                         {
   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;
 }

◆ CheckSeedBlobsCount()

bool tesseract::EquationDetect::CheckSeedBlobsCount ( ColPartition * part )

protected

Definition at line 983 of file equationdetect.cpp.

                                                            {
   if (!part) {
     return false;
   }
   const int kSeedMathBlobsCount = 2;
   const int kSeedMathDigitBlobsCount = 5;
  
   const 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;
 }

◆ CheckSeedDensity()

bool tesseract::EquationDetect::CheckSeedDensity	(	const float	math_density_high,
		const float	math_density_low,
		const ColPartition *	part
	)		const

protected

Definition at line 1001 of file equationdetect.cpp.

                                     {
   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;
 }

◆ CheckSeedFgDensity()

bool tesseract::EquationDetect::CheckSeedFgDensity	(	const float	density_th,
		ColPartition *	part
	)

protected

Definition at line 625 of file equationdetect.cpp.

                                                             {
   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) {
     const 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;
 }

◆ CheckSeedNeighborDensity()

bool tesseract::EquationDetect::CheckSeedNeighborDensity ( const ColPartition * part ) const

protected

Definition at line 1292 of file equationdetect.cpp.

                                                                             {
   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;
 }

◆ ComputeCPsSuperBBox()

void tesseract::EquationDetect::ComputeCPsSuperBBox ( )

protected

Definition at line 791 of file equationdetect.cpp.

                                          {
   ColPartitionGridSearch gsearch(part_grid_);
   ColPartition *part = nullptr;
   gsearch.StartFullSearch();
   delete cps_super_bbox_;
   cps_super_bbox_ = new TBOX();
   while ((part = gsearch.NextFullSearch()) != nullptr) {
     (*cps_super_bbox_) += part->bounding_box();
   }
 }

◆ ComputeForegroundDensity()

float tesseract::EquationDetect::ComputeForegroundDensity ( const TBOX & tbox )

protected

Definition at line 611 of file equationdetect.cpp.

                                                                {
   Pix *pix_bi = lang_tesseract_->pix_binary();
   const 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, nullptr);
   l_float32 fract;
   pixForegroundFraction(pix_sub, &fract);
   pixDestroy(&pix_sub);
   boxDestroy(&box);
  
   return fract;
 }

◆ CountAlignment()

int tesseract::EquationDetect::CountAlignment	(	const GenericVector< int > &	sorted_vec,
		const int	val
	)		const

protected

Definition at line 759 of file equationdetect.cpp.

                                                                {
   if (sorted_vec.empty()) {
     return 0;
   }
   const int kDistTh = static_cast<int>(roundf(0.03 * resolution_));
   const int pos = sorted_vec.binary_search(val);
   int 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;
 }

◆ EstimateTextPartLineSpacing()

int tesseract::EquationDetect::EstimateTextPartLineSpacing ( )

protected

Definition at line 867 of file equationdetect.cpp.

                                                 {
   ColPartitionGridSearch gsearch(part_grid_);
  
   // Get the y gap between text partitions;
   ColPartition *current = nullptr, *prev = nullptr;
   gsearch.StartFullSearch();
   GenericVector<int> ygaps;
   while ((current = gsearch.NextFullSearch()) != nullptr) {
     if (!PTIsTextType(current->type())) {
       continue;
     }
     if (prev != nullptr) {
       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 < std::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;
 }

◆ EstimateTypeForUnichar()

BlobSpecialTextType tesseract::EquationDetect::EstimateTypeForUnichar	(	const UNICHARSET &	unicharset,
		const UNICHAR_ID	id
	)		const

protected

Definition at line 224 of file equationdetect.cpp.

                                                              {
   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++].c_str()));
       }
       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;
   }
 }

◆ ExpandSeed()

bool tesseract::EquationDetect::ExpandSeed ( ColPartition * seed )

protected

Definition at line 1084 of file equationdetect.cpp.

                                                   {
   if (seed == nullptr ||  // 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 absorbs all parts_to_merge partitions.
   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 nullptr 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] = nullptr;
           break;
         }
       }
     }
  
     // part has already been removed from part_grid_ in function
     // ExpandSeedHorizontal/ExpandSeedVertical.
     seed->Absorb(part, nullptr);
   }
  
   return true;
 }

◆ ExpandSeedHorizontal()

void tesseract::EquationDetect::ExpandSeedHorizontal	(	const bool	search_left,
		ColPartition *	seed,
		GenericVector< ColPartition * > *	parts_to_merge
	)

protected

Definition at line 1127 of file equationdetect.cpp.

                                                   {
   ASSERT_HOST(seed != nullptr && parts_to_merge != nullptr);
   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());
   const 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 = nullptr;
   while ((part = search.NextSideSearch(search_left)) != nullptr) {
     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);
   }
 }

◆ ExpandSeedVertical()

void tesseract::EquationDetect::ExpandSeedVertical	(	const bool	search_bottom,
		ColPartition *	seed,
		GenericVector< ColPartition * > *	parts_to_merge
	)

protected

Definition at line 1183 of file equationdetect.cpp.

                                                   {
   ASSERT_HOST(seed != nullptr && parts_to_merge != nullptr &&
               cps_super_bbox_ != nullptr);
   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());
   const 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 = nullptr;
   GenericVector<ColPartition*> parts;
   int skipped_min_top = std::numeric_limits<int>::max(), skipped_max_bottom = -1;
   while ((part = search.NextVerticalSearch(search_bottom)) != nullptr) {
     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]);
   }
 }

◆ FindEquationParts()

int tesseract::EquationDetect::FindEquationParts	(	ColPartitionGrid *	part_grid,
		ColPartitionSet **	best_columns
	)

overridevirtual

Implements tesseract::EquationDetectBase.

Definition at line 358 of file equationdetect.cpp.

                                                                  {
   if (!lang_tesseract_) {
     tprintf("Warning: lang_tesseract_ is nullptr!\n");
     return -1;
   }
   if (!part_grid || !best_columns) {
     tprintf("part_grid/best_columns is nullptr!!\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.c_str(), 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;
 }

◆ GetOutputTiffName()

void tesseract::EquationDetect::GetOutputTiffName	(	const char *	name,
		STRING *	image_name
	)		const

protected

Definition at line 1456 of file equationdetect.cpp.

                                                                  {
   ASSERT_HOST(image_name && name);
   char page[50];
   snprintf(page, sizeof(page), "%04d", page_count_);
   *image_name = STRING(lang_tesseract_->imagebasename) + page + name + ".tif";
 }

◆ IdentifyBlobsToSkip()

void tesseract::EquationDetect::IdentifyBlobsToSkip ( ColPartition * part )

protected

Definition at line 310 of file equationdetect.cpp.

                                                            {
   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;
       const bool xoverlap = blob_box.major_x_overlap(nextblob_box),
           yoverlap = blob_box.y_overlap(nextblob_box);
       const float widthR = static_cast<float>(
           std::min(nextblob_box.width(), blob_box.width())) /
           std::max(nextblob_box.width(), blob_box.width());
       const float heightR = static_cast<float>(
           std::min(nextblob_box.height(), blob_box.height())) /
           std::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);
     }
   }
 }

◆ IdentifyInlineParts()

void tesseract::EquationDetect::IdentifyInlineParts ( )

protected

Definition at line 783 of file equationdetect.cpp.

                                          {
   ComputeCPsSuperBBox();
   IdentifyInlinePartsHorizontal();
   const int textparts_linespacing = EstimateTextPartLineSpacing();
   IdentifyInlinePartsVertical(true, textparts_linespacing);
   IdentifyInlinePartsVertical(false, textparts_linespacing);
 }

◆ IdentifyInlinePartsHorizontal()

void tesseract::EquationDetect::IdentifyInlinePartsHorizontal ( )

protected

Definition at line 802 of file equationdetect.cpp.

                                                    {
   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_.
   const 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());
     const 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 = nullptr;
     bool side_neighbor_found = false;
     while ((neighbor = search.NextSideSearch(right_to_left)) != nullptr) {
       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;
 }

◆ IdentifyInlinePartsVertical()

void tesseract::EquationDetect::IdentifyInlinePartsVertical	(	const bool	top_to_bottom,
		const int	textPartsLineSpacing
	)

protected

Definition at line 907 of file equationdetect.cpp.

                                                                {
   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;
 }

◆ IdentifySeedParts()

void tesseract::EquationDetect::IdentifySeedParts ( )

protected

Definition at line 539 of file equationdetect.cpp.

                                        {
   ColPartitionGridSearch gsearch(part_grid_);
   ColPartition *part = nullptr;
   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()) != nullptr) {
     if (!IsTextOrEquationType(part->type())) {
       continue;
     }
     part->ComputeSpecialBlobsDensity();
     const 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]);
     }
   }
 }

◆ IdentifySpecialText() [1/2]

void tesseract::EquationDetect::IdentifySpecialText ( )

protected

Definition at line 258 of file equationdetect.cpp.

                                          {
   // Set configuration for Tesseract::AdaptiveClassifier.
   equ_tesseract_.tess_cn_matching.set_value(1);  // turn it on
   equ_tesseract_.tess_bn_matching.set_value(0);
  
   // Set the multiplier to zero for lang_tesseract_ to improve the accuracy.
   const int classify_class_pruner = lang_tesseract_->classify_class_pruner_multiplier;
   const 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 = nullptr;
   gsearch.StartFullSearch();
   while ((part = gsearch.NextFullSearch()) != nullptr) {
     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();
     const 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);
   }
 }

◆ IdentifySpecialText() [2/2]

void tesseract::EquationDetect::IdentifySpecialText	(	BLOBNBOX *	blob,
		const int	height_th
	)

protected

Definition at line 151 of file equationdetect.cpp.

                                              {
   ASSERT_HOST(blobnbox != nullptr);
   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.
   const float scaling = static_cast<float>(kBlnXHeight) / box.height();
   const float x_orig = (box.left() + box.right()) / 2.0f, y_orig = box.bottom();
   std::unique_ptr<TBLOB> normed_blob(new TBLOB(*tblob));
   normed_blob->Normalize(nullptr, nullptr, nullptr, x_orig, y_orig, scaling, scaling,
                          0.0f, static_cast<float>(kBlnBaselineOffset),
                          false, nullptr);
   equ_tesseract_.AdaptiveClassifier(normed_blob.get(), &ratings_equ);
   lang_tesseract_->AdaptiveClassifier(normed_blob.get(), &ratings_lang);
   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 = nullptr, *equ_choice = nullptr;
   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();
   }
  
   const float lang_score = lang_choice ? lang_choice->certainty() : -FLT_MAX;
   const 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);
   const 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);
   }
 }

◆ InsertPartAfterAbsorb()

void tesseract::EquationDetect::InsertPartAfterAbsorb ( ColPartition * part )

protected

Definition at line 512 of file equationdetect.cpp.

                                                              {
   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);
 }

◆ IsIndented()

EquationDetect::IndentType tesseract::EquationDetect::IsIndented ( ColPartition * part )

protected

Definition at line 1020 of file equationdetect.cpp.

                                                                       {
   ASSERT_HOST(part);
  
   ColPartitionGridSearch search(part_grid_);
   ColPartition *neighbor = nullptr;
   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 partition
   // 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()) != nullptr &&
          (!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) {
       const int left_gap = part_box.left() - neighbor_box.left();
       const 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;
 }

◆ IsInline()

bool tesseract::EquationDetect::IsInline	(	const bool	search_bottom,
		const int	textPartsLineSpacing,
		ColPartition *	part
	)

protected

Definition at line 936 of file equationdetect.cpp.

                                                   {
   ASSERT_HOST(part != nullptr);
   // Look for its nearest vertical neighbor that hardly overlaps in y but
   // largely overlaps in x.
   ColPartitionGridSearch search(part_grid_);
   ColPartition *neighbor = nullptr;
   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)) != nullptr) {
     const TBOX& neighbor_box(neighbor->bounding_box());
     if (part_box.y_gap(neighbor_box) > kYGapRatioTh *
              std::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>(std::min(part_box.height(), neighbor_box.height())) /
         std::max(part_box.height(), neighbor_box.height()) > kHeightRatioTh) {
       return true;
     }
   }
  
   return false;
 }

◆ IsMathBlockSatellite()

bool tesseract::EquationDetect::IsMathBlockSatellite	(	ColPartition *	part,
		GenericVector< ColPartition * > *	math_blocks
	)

protected

Definition at line 1358 of file equationdetect.cpp.

                                                                    {
   ASSERT_HOST(part != nullptr && math_blocks != nullptr);
   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] = {std::numeric_limits<int>::max(), std::numeric_limits<int>::max()};
   // The horizontal boundary of the neighbors.
   int neighbors_left = std::numeric_limits<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] = nullptr;
     y_gaps[1] = std::numeric_limits<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;
 }

◆ IsNearMathNeighbor()

bool tesseract::EquationDetect::IsNearMathNeighbor	(	const int	y_gap,
		const ColPartition *	neighbor
	)		const

protected

Definition at line 1447 of file equationdetect.cpp.

                                                          {
   if (!neighbor) {
     return false;
   }
   const int kYGapTh = static_cast<int>(roundf(resolution_ * 0.1));
   return neighbor->type() == PT_EQUATION && y_gap <= kYGapTh;
 }

◆ IsNearSmallNeighbor()

bool tesseract::EquationDetect::IsNearSmallNeighbor	(	const TBOX &	seed_box,
		const TBOX &	part_box
	)		const

protected

Definition at line 1270 of file equationdetect.cpp.

                                                                      {
   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;
 }

◆ LabelSpecialText()

int tesseract::EquationDetect::LabelSpecialText ( TO_BLOCK * to_block )

overridevirtual

Implements tesseract::EquationDetectBase.

Definition at line 131 of file equationdetect.cpp.

                                                        {
   if (to_block == nullptr) {
     tprintf("Warning: input to_block is nullptr!\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;
 }

◆ MergePartsByLocation()

void tesseract::EquationDetect::MergePartsByLocation ( )

protected

Definition at line 424 of file equationdetect.cpp.

                                           {
   while (true) {
     ColPartition* part = nullptr;
     // partitions that have been updated.
     GenericVector<ColPartition*> parts_updated;
     ColPartitionGridSearch gsearch(part_grid_);
     gsearch.StartFullSearch();
     while ((part = gsearch.NextFullSearch()) != nullptr) {
       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] != nullptr && parts_to_merge[i] != part);
         part->Absorb(parts_to_merge[i], nullptr);
       }
       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]);
     }
   }
 }

◆ PaintColParts()

void tesseract::EquationDetect::PaintColParts ( const STRING & outfile ) const

protected

Definition at line 1481 of file equationdetect.cpp.

                                                               {
   Pix *pix = pixConvertTo32(lang_tesseract_->BestPix());
   ColPartitionGridSearch gsearch(part_grid_);
   gsearch.StartFullSearch();
   ColPartition* part = nullptr;
   while ((part = gsearch.NextFullSearch()) != nullptr) {
     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.c_str(), pix, IFF_TIFF_LZW);
   pixDestroy(&pix);
 }

◆ PaintSpecialTexts()

void tesseract::EquationDetect::PaintSpecialTexts ( const STRING & outfile ) const

protected

Definition at line 1464 of file equationdetect.cpp.

                                                                   {
   Pix *pix = nullptr, *pixBi = lang_tesseract_->pix_binary();
   pix = pixConvertTo32(pixBi);
   ColPartitionGridSearch gsearch(part_grid_);
   ColPartition* part = nullptr;
   gsearch.StartFullSearch();
   while ((part = gsearch.NextFullSearch()) != nullptr) {
     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.c_str(), pix, IFF_TIFF_LZW);
   pixDestroy(&pix);
 }

◆ PrintSpecialBlobsDensity()

void tesseract::EquationDetect::PrintSpecialBlobsDensity ( const ColPartition * part ) const

protected

Definition at line 1504 of file equationdetect.cpp.

                                                                             {
   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) {
     auto type = static_cast<BlobSpecialTextType>(i);
     tprintf("%d:%f ", i, part->SpecialBlobsDensity(type));
   }
   tprintf("\n");
 }

◆ ProcessMathBlockSatelliteParts()

void tesseract::EquationDetect::ProcessMathBlockSatelliteParts ( )

protected

Definition at line 1309 of file equationdetect.cpp.

                                                     {
   // Iterate over part_grid_, and find all parts that are text type but not
   // equation type.
   ColPartition *part = nullptr;
   GenericVector<ColPartition*> text_parts;
   ColPartitionGridSearch gsearch(part_grid_);
   gsearch.StartFullSearch();
   while ((part = gsearch.NextFullSearch()) != nullptr) {
     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], nullptr);
     }
     InsertPartAfterAbsorb(text_parts[i]);
   }
 }

◆ SearchByOverlap()

void tesseract::EquationDetect::SearchByOverlap	(	ColPartition *	seed,
		GenericVector< ColPartition * > *	parts_overlap
	)

protected

Definition at line 463 of file equationdetect.cpp.

                                                  {
   ASSERT_HOST(seed != nullptr && parts_overlap != nullptr);
   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()) != nullptr) {
     if (part == seed || !IsTextOrEquationType(part->type())) {
       continue;
     }
     const TBOX& part_box(part->bounding_box());
     bool merge = false;
  
     const 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);
     }
   }
 }

◆ SearchNNVertical()

ColPartition * tesseract::EquationDetect::SearchNNVertical	(	const bool	search_bottom,
		const ColPartition *	part
	)

protected

Definition at line 1412 of file equationdetect.cpp.

                                                         {
   ASSERT_HOST(part);
   ColPartition *nearest_neighbor = nullptr, *neighbor = nullptr;
   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 = std::numeric_limits<int>::max();
   while ((neighbor = search.NextVerticalSearch(search_bottom)) != nullptr) {
     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;
 }

◆ SetLangTesseract()

void tesseract::EquationDetect::SetLangTesseract ( Tesseract * lang_tesseract )

Definition at line 123 of file equationdetect.cpp.

                                                                {
   lang_tesseract_ = lang_tesseract;
 }

◆ SetResolution()

void tesseract::EquationDetect::SetResolution ( const int resolution )

Definition at line 127 of file equationdetect.cpp.

                                                        {
   resolution_ = resolution;
 }

◆ SplitCPHor()

void tesseract::EquationDetect::SplitCPHor	(	ColPartition *	part,
		GenericVector< ColPartition * > *	parts_splitted
	)

protected

Definition at line 647 of file equationdetect.cpp.

                                                    {
   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 = INT32_MIN;
  
     // 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 != INT32_MIN &&
           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.
         const 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 = std::max(previous_right, static_cast<int>(box.right()));
     }
   }
  
   // Add the last piece.
   right_part->ComputeSpecialBlobsDensity();
   parts_splitted->push_back(right_part);
 }

◆ SplitCPHorLite()

void tesseract::EquationDetect::SplitCPHorLite	(	ColPartition *	part,
		GenericVector< TBOX > *	splitted_boxes
	)

protected

Definition at line 697 of file equationdetect.cpp.

                                           {
   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 = INT32_MIN;
   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 != INT32_MIN &&
         box.left() - previous_right > kThreshold) {
       // We have a split position.
       splitted_boxes->push_back(union_box);
       previous_right = INT32_MIN;
     }
     if (previous_right == INT32_MIN) {
       union_box = box;
     } else {
       union_box += box;
     }
     // The right side of the previous blobs.
     previous_right = std::max(previous_right, static_cast<int>(box.right()));
   }
  
   // Add the last piece.
   if (previous_right != INT32_MIN) {
     splitted_boxes->push_back(union_box);
   }
 }

Member Data Documentation

◆ best_columns_

ColPartitionSet** tesseract::EquationDetect::best_columns_ = nullptr

protected

Definition at line 256 of file equationdetect.h.

◆ cp_seeds_

GenericVector<ColPartition*> tesseract::EquationDetect::cp_seeds_

protected

Definition at line 262 of file equationdetect.h.

◆ cps_super_bbox_

TBOX* tesseract::EquationDetect::cps_super_bbox_

protected

Definition at line 259 of file equationdetect.h.

◆ equ_tesseract_

Tesseract tesseract::EquationDetect::equ_tesseract_

protected

Definition at line 243 of file equationdetect.h.

◆ lang_tesseract_

Tesseract* tesseract::EquationDetect::lang_tesseract_

protected

Definition at line 247 of file equationdetect.h.

◆ page_count_

int tesseract::EquationDetect::page_count_

protected

Definition at line 268 of file equationdetect.h.

◆ part_grid_

ColPartitionGrid* tesseract::EquationDetect::part_grid_ = nullptr

protected

Definition at line 251 of file equationdetect.h.

◆ resolution_

int tesseract::EquationDetect::resolution_

protected

Definition at line 265 of file equationdetect.h.

The documentation for this class was generated from the following files:

/tesseract/src/ccmain/equationdetect.h
/tesseract/src/ccmain/equationdetect.cpp

Public Types

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Member Enumeration Documentation

◆ IndentType

Constructor & Destructor Documentation

◆ EquationDetect()

◆ ~EquationDetect()

Member Function Documentation

◆ CheckForSeed2()

◆ CheckSeedBlobsCount()

◆ CheckSeedDensity()

◆ CheckSeedFgDensity()

◆ CheckSeedNeighborDensity()

◆ ComputeCPsSuperBBox()

◆ ComputeForegroundDensity()

◆ CountAlignment()

◆ EstimateTextPartLineSpacing()

◆ EstimateTypeForUnichar()

◆ ExpandSeed()

◆ ExpandSeedHorizontal()

◆ ExpandSeedVertical()

◆ FindEquationParts()

◆ GetOutputTiffName()

◆ IdentifyBlobsToSkip()

◆ IdentifyInlineParts()

◆ IdentifyInlinePartsHorizontal()

◆ IdentifyInlinePartsVertical()

◆ IdentifySeedParts()

◆ IdentifySpecialText() [1/2]

◆ IdentifySpecialText() [2/2]

◆ InsertPartAfterAbsorb()

◆ IsIndented()

◆ IsInline()

◆ IsMathBlockSatellite()

◆ IsNearMathNeighbor()

◆ IsNearSmallNeighbor()

◆ LabelSpecialText()

◆ MergePartsByLocation()

◆ PaintColParts()

◆ PaintSpecialTexts()

◆ PrintSpecialBlobsDensity()

◆ ProcessMathBlockSatelliteParts()

◆ SearchByOverlap()

◆ SearchNNVertical()

◆ SetLangTesseract()

◆ SetResolution()

◆ SplitCPHor()

◆ SplitCPHorLite()

Member Data Documentation

◆ best_columns_

◆ cp_seeds_

◆ cps_super_bbox_

◆ equ_tesseract_

◆ lang_tesseract_

◆ page_count_

◆ part_grid_

◆ resolution_