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tesseract/textord/colfind.cpp

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///////////////////////////////////////////////////////////////////////
// File: colfind.cpp
// Description: Class to hold BLOBNBOXs in a grid for fast access
// to neighbours.
// Author: Ray Smith
// Created: Wed Jun 06 17:22:01 PDT 2007
//
// (C) Copyright 2007, 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
#endif
// Include automatically generated configuration file if running autoconf.
#ifdef HAVE_CONFIG_H
#include "config_auto.h"
#endif
#include "colfind.h"
#include "ccnontextdetect.h"
#include "colpartition.h"
#include "colpartitionset.h"
#include "equationdetectbase.h"
#include "linefind.h"
#include "normalis.h"
#include "strokewidth.h"
#include "blobbox.h"
#include "scrollview.h"
#include "tablefind.h"
#include "params.h"
#include "workingpartset.h"
namespace tesseract {
// Minimum width (in pixels) to be considered when making columns.
// TODO(rays) convert to inches, dependent on resolution.
const int kMinColumnWidth = 100;
// When assigning columns, the max number of misfit grid rows/ColPartitionSets
// that can be ignored.
const int kMaxIncompatibleColumnCount = 2;
// Min fraction of ColPartition height to be overlapping for margin purposes.
const double kMarginOverlapFraction = 0.25;
// Max fraction of mean_column_gap_ for the gap between two partitions within a
// column to allow them to merge.
const double kHorizontalGapMergeFraction = 0.5;
// Min fraction of grid size to not be considered likely noise.
const double kMinNonNoiseFraction = 0.5;
// Minimum gutter width as a fraction of gridsize
const double kMinGutterWidthGrid = 0.5;
// Max multiple of a partition's median size as a distance threshold for
// adding noise blobs.
const double kMaxDistToPartSizeRatio = 1.5;
BOOL_VAR(textord_tabfind_show_initial_partitions,
false, "Show partition bounds");
BOOL_VAR(textord_tabfind_show_reject_blobs,
false, "Show blobs rejected as noise");
INT_VAR(textord_tabfind_show_partitions, 0,
"Show partition bounds, waiting if >1");
BOOL_VAR(textord_tabfind_show_columns, false, "Show column bounds");
BOOL_VAR(textord_tabfind_show_blocks, false, "Show final block bounds");
BOOL_VAR(textord_tabfind_find_tables, true, "run table detection");
ScrollView* ColumnFinder::blocks_win_ = NULL;
// Gridsize is an estimate of the text size in the image. A suitable value
// is in TO_BLOCK::line_size after find_components has been used to make
// the blobs.
// bleft and tright are the bounds of the image (or rectangle) being processed.
// vlines is a (possibly empty) list of TabVector and vertical_x and y are
// the sum logical vertical vector produced by LineFinder::FindVerticalLines.
ColumnFinder::ColumnFinder(int gridsize,
const ICOORD& bleft, const ICOORD& tright,
int resolution, bool cjk_script,
double aligned_gap_fraction,
TabVector_LIST* vlines, TabVector_LIST* hlines,
int vertical_x, int vertical_y)
: TabFind(gridsize, bleft, tright, vlines, vertical_x, vertical_y,
resolution),
cjk_script_(cjk_script),
min_gutter_width_(static_cast<int>(kMinGutterWidthGrid * gridsize)),
mean_column_gap_(tright.x() - bleft.x()),
tabfind_aligned_gap_fraction_(aligned_gap_fraction),
reskew_(1.0f, 0.0f), rotation_(1.0f, 0.0f), rerotate_(1.0f, 0.0f),
best_columns_(NULL), stroke_width_(NULL),
part_grid_(gridsize, bleft, tright), nontext_map_(NULL),
projection_(resolution),
denorm_(NULL), input_blobs_win_(NULL), equation_detect_(NULL) {
TabVector_IT h_it(&horizontal_lines_);
h_it.add_list_after(hlines);
}
ColumnFinder::~ColumnFinder() {
column_sets_.delete_data_pointers();
if (best_columns_ != NULL) {
delete [] best_columns_;
}
if (stroke_width_ != NULL)
delete stroke_width_;
delete input_blobs_win_;
pixDestroy(&nontext_map_);
while (denorm_ != NULL) {
DENORM* dead_denorm = denorm_;
denorm_ = const_cast<DENORM*>(denorm_->predecessor());
delete dead_denorm;
}
// The ColPartitions are destroyed automatically, but any boxes in
// the noise_parts_ list are owned and need to be deleted explicitly.
ColPartition_IT part_it(&noise_parts_);
for (part_it.mark_cycle_pt(); !part_it.cycled_list(); part_it.forward()) {
ColPartition* part = part_it.data();
part->DeleteBoxes();
}
// Likewise any boxes in the good_parts_ list need to be deleted.
// These are just the image parts. Text parts have already given their
// boxes on to the TO_BLOCK, and have empty lists.
part_it.set_to_list(&good_parts_);
for (part_it.mark_cycle_pt(); !part_it.cycled_list(); part_it.forward()) {
ColPartition* part = part_it.data();
part->DeleteBoxes();
}
// Also, any blobs on the image_bblobs_ list need to have their cblobs
// deleted. This only happens if there has been an early return from
// FindColumns, as in a normal return, the blobs go into the grid and
// end up in noise_parts_, good_parts_ or the output blocks.
BLOBNBOX_IT bb_it(&image_bblobs_);
for (bb_it.mark_cycle_pt(); !bb_it.cycled_list(); bb_it.forward()) {
BLOBNBOX* bblob = bb_it.data();
delete bblob->cblob();
}
}
// Performs initial processing on the blobs in the input_block:
// Setup the part_grid, stroke_width_, nontext_map.
// Obvious noise blobs are filtered out and used to mark the nontext_map_.
// Initial stroke-width analysis is used to get local text alignment
// direction, so the textline projection_ map can be setup.
// On return, IsVerticallyAlignedText may be called (now optionally) to
// determine the gross textline alignment of the page.
void ColumnFinder::SetupAndFilterNoise(PageSegMode pageseg_mode,
Pix* photo_mask_pix,
TO_BLOCK* input_block) {
part_grid_.Init(gridsize(), bleft(), tright());
if (stroke_width_ != NULL)
delete stroke_width_;
stroke_width_ = new StrokeWidth(gridsize(), bleft(), tright());
min_gutter_width_ = static_cast<int>(kMinGutterWidthGrid * gridsize());
input_block->ReSetAndReFilterBlobs();
#ifndef GRAPHICS_DISABLED
if (textord_tabfind_show_blocks) {
input_blobs_win_ = MakeWindow(0, 0, "Filtered Input Blobs");
input_block->plot_graded_blobs(input_blobs_win_);
}
#endif // GRAPHICS_DISABLED
SetBlockRuleEdges(input_block);
pixDestroy(&nontext_map_);
// Run a preliminary strokewidth neighbour detection on the medium blobs.
stroke_width_->SetNeighboursOnMediumBlobs(input_block);
CCNonTextDetect nontext_detect(gridsize(), bleft(), tright());
// Remove obvious noise and make the initial non-text map.
nontext_map_ = nontext_detect.ComputeNonTextMask(textord_debug_tabfind,
photo_mask_pix, input_block);
stroke_width_->FindTextlineDirectionAndFixBrokenCJK(pageseg_mode, cjk_script_,
input_block);
// Clear the strokewidth grid ready for rotation or leader finding.
stroke_width_->Clear();
}
// Tests for vertical alignment of text (returning true if so), and generates
// a list of blobs of moderate aspect ratio, in the most frequent writing
// direction (in osd_blobs) for orientation and script detection to test
// the character orientation.
// block is the single block for the whole page or rectangle to be OCRed.
// Note that the vertical alignment may be due to text whose writing direction
// is vertical, like say Japanese, or due to text whose writing direction is
// horizontal but whose text appears vertically aligned because the image is
// not the right way up.
bool ColumnFinder::IsVerticallyAlignedText(double find_vertical_text_ratio,
TO_BLOCK* block,
BLOBNBOX_CLIST* osd_blobs) {
return stroke_width_->TestVerticalTextDirection(find_vertical_text_ratio,
block, osd_blobs);
}
// Rotates the blobs and the TabVectors so that the gross writing direction
// (text lines) are horizontal and lines are read down the page.
// Applied rotation stored in rotation_.
// A second rotation is calculated for application during recognition to
// make the rotated blobs upright for recognition.
// Subsequent rotation stored in text_rotation_.
//
// Arguments:
// vertical_text_lines true if the text lines are vertical.
// recognition_rotation [0..3] is the number of anti-clockwise 90 degree
// rotations from osd required for the text to be upright and readable.
void ColumnFinder::CorrectOrientation(TO_BLOCK* block,
bool vertical_text_lines,
int recognition_rotation) {
const FCOORD anticlockwise90(0.0f, 1.0f);
const FCOORD clockwise90(0.0f, -1.0f);
const FCOORD rotation180(-1.0f, 0.0f);
const FCOORD norotation(1.0f, 0.0f);
text_rotation_ = norotation;
// Rotate the page to make the text upright, as implied by
// recognition_rotation.
rotation_ = norotation;
if (recognition_rotation == 1) {
rotation_ = anticlockwise90;
} else if (recognition_rotation == 2) {
rotation_ = rotation180;
} else if (recognition_rotation == 3) {
rotation_ = clockwise90;
}
// We infer text writing direction to be vertical if there are several
// vertical text lines detected, and horizontal if not. But if the page
// orientation was determined to be 90 or 270 degrees, the true writing
// direction is the opposite of what we inferred.
if (recognition_rotation & 1) {
vertical_text_lines = !vertical_text_lines;
}
// If we still believe the writing direction is vertical, we use the
// convention of rotating the page ccw 90 degrees to make the text lines
// horizontal, and mark the blobs for rotation cw 90 degrees for
// classification so that the text order is correct after recognition.
if (vertical_text_lines) {
rotation_.rotate(anticlockwise90);
text_rotation_.rotate(clockwise90);
}
// Set rerotate_ to the inverse of rotation_.
rerotate_ = FCOORD(rotation_.x(), -rotation_.y());
if (rotation_.x() != 1.0f || rotation_.y() != 0.0f) {
// Rotate all the blobs and tab vectors.
RotateBlobList(rotation_, &block->large_blobs);
RotateBlobList(rotation_, &block->blobs);
RotateBlobList(rotation_, &block->small_blobs);
RotateBlobList(rotation_, &block->noise_blobs);
TabFind::ResetForVerticalText(rotation_, rerotate_, &horizontal_lines_,
&min_gutter_width_);
part_grid_.Init(gridsize(), bleft(), tright());
// Reset all blobs to initial state and filter by size.
// Since they have rotated, the list they belong on could have changed.
block->ReSetAndReFilterBlobs();
SetBlockRuleEdges(block);
stroke_width_->CorrectForRotation(rerotate_, &part_grid_);
}
if (textord_debug_tabfind) {
tprintf("Vertical=%d, orientation=%d, final rotation=(%f, %f)+(%f,%f)\n",
vertical_text_lines, recognition_rotation,
rotation_.x(), rotation_.y(),
text_rotation_.x(), text_rotation_.y());
}
// Setup the denormalization.
ASSERT_HOST(denorm_ == NULL);
denorm_ = new DENORM;
denorm_->SetupNormalization(NULL, &rotation_, NULL,
0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f);
}
// Finds blocks of text, image, rule line, table etc, returning them in the
// blocks and to_blocks
// (Each TO_BLOCK points to the basic BLOCK and adds more information.)
// Image blocks are generated by a combination of photo_mask_pix (which may
// NOT be NULL) and the rejected text found during preliminary textline
// finding.
// The input_block is the result of a call to find_components, and contains
// the blobs found in the image or rectangle to be OCRed. These blobs will be
// removed and placed in the output blocks, while unused ones will be deleted.
// If single_column is true, the input is treated as single column, but
// it is still divided into blocks of equal line spacing/text size.
// scaled_color is scaled down by scaled_factor from the input color image,
// and may be NULL if the input was not color.
// grey_pix is optional, but if present must match the photo_mask_pix in size,
// and must be a *real* grey image instead of binary_pix * 255.
// thresholds_pix is expected to be present iff grey_pix is present and
// can be an integer factor reduction of the grey_pix. It represents the
// thresholds that were used to create the binary_pix from the grey_pix.
// If diacritic_blobs is non-null, then diacritics/noise blobs, that would
// confuse layout anaylsis by causing textline overlap, are placed there,
// with the expectation that they will be reassigned to words later and
// noise/diacriticness determined via classification.
// Returns -1 if the user hits the 'd' key in the blocks window while running
// in debug mode, which requests a retry with more debug info.
int ColumnFinder::FindBlocks(PageSegMode pageseg_mode, Pix* scaled_color,
int scaled_factor, TO_BLOCK* input_block,
Pix* photo_mask_pix, Pix* thresholds_pix,
Pix* grey_pix, BLOCK_LIST* blocks,
BLOBNBOX_LIST* diacritic_blobs,
TO_BLOCK_LIST* to_blocks) {
pixOr(photo_mask_pix, photo_mask_pix, nontext_map_);
stroke_width_->FindLeaderPartitions(input_block, &part_grid_);
stroke_width_->RemoveLineResidue(&big_parts_);
FindInitialTabVectors(NULL, min_gutter_width_, tabfind_aligned_gap_fraction_,
input_block);
SetBlockRuleEdges(input_block);
stroke_width_->GradeBlobsIntoPartitions(
pageseg_mode, rerotate_, input_block, nontext_map_, denorm_, cjk_script_,
&projection_, diacritic_blobs, &part_grid_, &big_parts_);
if (!PSM_SPARSE(pageseg_mode)) {
ImageFind::FindImagePartitions(photo_mask_pix, rotation_, rerotate_,
input_block, this, &part_grid_, &big_parts_);
ImageFind::TransferImagePartsToImageMask(rerotate_, &part_grid_,
photo_mask_pix);
ImageFind::FindImagePartitions(photo_mask_pix, rotation_, rerotate_,
input_block, this, &part_grid_, &big_parts_);
}
part_grid_.ReTypeBlobs(&image_bblobs_);
TidyBlobs(input_block);
Reset();
// TODO(rays) need to properly handle big_parts_.
ColPartition_IT p_it(&big_parts_);
for (p_it.mark_cycle_pt(); !p_it.cycled_list(); p_it.forward())
p_it.data()->DisownBoxesNoAssert();
big_parts_.clear();
delete stroke_width_;
stroke_width_ = NULL;
// Compute the edge offsets whether or not there is a grey_pix. It is done
// here as the c_blobs haven't been touched by rotation or anything yet,
// so no denorm is required, yet the text has been separated from image, so
// no time is wasted running it on image blobs.
input_block->ComputeEdgeOffsets(thresholds_pix, grey_pix);
// A note about handling right-to-left scripts (Hebrew/Arabic):
// The columns must be reversed and come out in right-to-left instead of
// the normal left-to-right order. Because the left-to-right ordering
// is implicit in many data structures, it is simpler to fool the algorithms
// into thinking they are dealing with left-to-right text.
// To do this, we reflect the needed data in the y-axis and then reflect
// the blocks back after they have been created. This is a temporary
// arrangment that is confined to this function only, so the reflection
// is completely invisible in the output blocks.
// The only objects reflected are:
// The vertical separator lines that have already been found;
// The bounding boxes of all BLOBNBOXES on all lists on the input_block
// plus the image_bblobs. The outlines are not touched, since they are
// not looked at.
bool input_is_rtl = input_block->block->right_to_left();
if (input_is_rtl) {
// Reflect the vertical separator lines (member of TabFind).
ReflectInYAxis();
// Reflect the blob boxes.
ReflectForRtl(input_block, &image_bblobs_);
part_grid_.ReflectInYAxis();
}
if (!PSM_SPARSE(pageseg_mode)) {
if (!PSM_COL_FIND_ENABLED(pageseg_mode)) {
// No tab stops needed. Just the grid that FindTabVectors makes.
DontFindTabVectors(&image_bblobs_, input_block, &deskew_, &reskew_);
} else {
SetBlockRuleEdges(input_block);
// Find the tab stops, estimate skew, and deskew the tabs, blobs and
// part_grid_.
FindTabVectors(&horizontal_lines_, &image_bblobs_, input_block,
min_gutter_width_, tabfind_aligned_gap_fraction_,
&part_grid_, &deskew_, &reskew_);
// Add the deskew to the denorm_.
DENORM* new_denorm = new DENORM;
new_denorm->SetupNormalization(NULL, &deskew_, denorm_,
0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0.0f);
denorm_ = new_denorm;
}
SetBlockRuleEdges(input_block);
part_grid_.SetTabStops(this);
// Make the column_sets_.
if (!MakeColumns(false)) {
tprintf("Empty page!!\n");
part_grid_.DeleteParts();
return 0; // This is an empty page.
}
// Refill the grid using rectangular spreading, and get the benefit
// of the completed tab vectors marking the rule edges of each blob.
Clear();
#ifndef GRAPHICS_DISABLED
if (textord_tabfind_show_reject_blobs) {
ScrollView* rej_win = MakeWindow(500, 300, "Rejected blobs");
input_block->plot_graded_blobs(rej_win);
}
#endif // GRAPHICS_DISABLED
InsertBlobsToGrid(false, false, &image_bblobs_, this);
InsertBlobsToGrid(true, true, &input_block->blobs, this);
part_grid_.GridFindMargins(best_columns_);
// Split and merge the partitions by looking at local neighbours.
GridSplitPartitions();
// Resolve unknown partitions by adding to an existing partition, fixing
// the type, or declaring them noise.
part_grid_.GridFindMargins(best_columns_);
GridMergePartitions();
// Insert any unused noise blobs that are close enough to an appropriate
// partition.
InsertRemainingNoise(input_block);
// Add horizontal line separators as partitions.
GridInsertHLinePartitions();
GridInsertVLinePartitions();
// Recompute margins based on a local neighbourhood search.
part_grid_.GridFindMargins(best_columns_);
SetPartitionTypes();
}
if (textord_tabfind_show_initial_partitions) {
ScrollView* part_win = MakeWindow(100, 300, "InitialPartitions");
part_grid_.DisplayBoxes(part_win);
DisplayTabVectors(part_win);
}
if (!PSM_SPARSE(pageseg_mode)) {
if (equation_detect_) {
equation_detect_->FindEquationParts(&part_grid_, best_columns_);
}
if (textord_tabfind_find_tables) {
TableFinder table_finder;
table_finder.Init(gridsize(), bleft(), tright());
table_finder.set_resolution(resolution_);
table_finder.set_left_to_right_language(
!input_block->block->right_to_left());
// Copy cleaned partitions from part_grid_ to clean_part_grid_ and
// insert dot-like noise into period_grid_
table_finder.InsertCleanPartitions(&part_grid_, input_block);
// Get Table Regions
table_finder.LocateTables(&part_grid_, best_columns_, WidthCB(), reskew_);
}
GridRemoveUnderlinePartitions();
part_grid_.DeleteUnknownParts(input_block);
// Build the partitions into chains that belong in the same block and
// refine into one-to-one links, then smooth the types within each chain.
part_grid_.FindPartitionPartners();
part_grid_.FindFigureCaptions();
part_grid_.RefinePartitionPartners(true);
SmoothPartnerRuns();
#ifndef GRAPHICS_DISABLED
if (textord_tabfind_show_partitions) {
ScrollView* window = MakeWindow(400, 300, "Partitions");
if (window != NULL) {
if (textord_debug_images)
window->Image(AlignedBlob::textord_debug_pix().string(),
image_origin().x(), image_origin().y());
part_grid_.DisplayBoxes(window);
if (!textord_debug_printable)
DisplayTabVectors(window);
if (window != NULL && textord_tabfind_show_partitions > 1) {
delete window->AwaitEvent(SVET_DESTROY);
}
}
}
#endif // GRAPHICS_DISABLED
part_grid_.AssertNoDuplicates();
}
// Ownership of the ColPartitions moves from part_sets_ to part_grid_ here,
// and ownership of the BLOBNBOXes moves to the ColPartitions.
// (They were previously owned by the block or the image_bblobs list.)
ReleaseBlobsAndCleanupUnused(input_block);
// Ownership of the ColPartitions moves from part_grid_ to good_parts_ and
// noise_parts_ here. In text blocks, ownership of the BLOBNBOXes moves
// from the ColPartitions to the output TO_BLOCK. In non-text, the
// BLOBNBOXes stay with the ColPartitions and get deleted in the destructor.
if (PSM_SPARSE(pageseg_mode))
part_grid_.ExtractPartitionsAsBlocks(blocks, to_blocks);
else
TransformToBlocks(blocks, to_blocks);
if (textord_debug_tabfind) {
tprintf("Found %d blocks, %d to_blocks\n",
blocks->length(), to_blocks->length());
}
DisplayBlocks(blocks);
RotateAndReskewBlocks(input_is_rtl, to_blocks);
int result = 0;
#ifndef GRAPHICS_DISABLED
if (blocks_win_ != NULL) {
bool waiting = false;
do {
waiting = false;
SVEvent* event = blocks_win_->AwaitEvent(SVET_ANY);
if (event->type == SVET_INPUT && event->parameter != NULL) {
if (*event->parameter == 'd')
result = -1;
else
blocks->clear();
} else if (event->type == SVET_DESTROY) {
blocks_win_ = NULL;
} else {
waiting = true;
}
delete event;
} while (waiting);
}
#endif // GRAPHICS_DISABLED
return result;
}
// Get the rotation required to deskew, and its inverse rotation.
void ColumnFinder::GetDeskewVectors(FCOORD* deskew, FCOORD* reskew) {
*reskew = reskew_;
*deskew = reskew_;
deskew->set_y(-deskew->y());
}
void ColumnFinder::SetEquationDetect(EquationDetectBase* detect) {
equation_detect_ = detect;
}
//////////////// PRIVATE CODE /////////////////////////
// Displays the blob and block bounding boxes in a window called Blocks.
void ColumnFinder::DisplayBlocks(BLOCK_LIST* blocks) {
#ifndef GRAPHICS_DISABLED
if (textord_tabfind_show_blocks) {
if (blocks_win_ == NULL)
blocks_win_ = MakeWindow(700, 300, "Blocks");
else
blocks_win_->Clear();
if (textord_debug_images)
blocks_win_->Image(AlignedBlob::textord_debug_pix().string(),
image_origin().x(), image_origin().y());
else
DisplayBoxes(blocks_win_);
BLOCK_IT block_it(blocks);
int serial = 1;
for (block_it.mark_cycle_pt(); !block_it.cycled_list();
block_it.forward()) {
BLOCK* block = block_it.data();
block->plot(blocks_win_, serial++,
textord_debug_printable ? ScrollView::BLUE
: ScrollView::GREEN);
}
blocks_win_->Update();
}
#endif
}
// Displays the column edges at each grid y coordinate defined by
// best_columns_.
void ColumnFinder::DisplayColumnBounds(PartSetVector* sets) {
#ifndef GRAPHICS_DISABLED
ScrollView* col_win = MakeWindow(50, 300, "Columns");
if (textord_debug_images)
col_win->Image(AlignedBlob::textord_debug_pix().string(),
image_origin().x(), image_origin().y());
else
DisplayBoxes(col_win);
col_win->Pen(textord_debug_printable ? ScrollView::BLUE : ScrollView::GREEN);
for (int i = 0; i < gridheight_; ++i) {
ColPartitionSet* columns = best_columns_[i];
if (columns != NULL)
columns->DisplayColumnEdges(i * gridsize_, (i + 1) * gridsize_, col_win);
}
#endif
}
// Sets up column_sets_ (the determined column layout at each horizontal
// slice). Returns false if the page is empty.
bool ColumnFinder::MakeColumns(bool single_column) {
// The part_sets_ are a temporary structure used during column creation,
// and is a vector of ColPartitionSets, representing ColPartitions found
// at horizontal slices through the page.
PartSetVector part_sets;
if (!single_column) {
if (!part_grid_.MakeColPartSets(&part_sets))
return false; // Empty page.
ASSERT_HOST(part_grid_.gridheight() == gridheight_);
// Try using only the good parts first.
bool good_only = true;
do {
for (int i = 0; i < gridheight_; ++i) {
ColPartitionSet* line_set = part_sets.get(i);
if (line_set != NULL && line_set->LegalColumnCandidate()) {
ColPartitionSet* column_candidate = line_set->Copy(good_only);
if (column_candidate != NULL)
column_candidate->AddToColumnSetsIfUnique(&column_sets_, WidthCB());
}
}
good_only = !good_only;
} while (column_sets_.empty() && !good_only);
if (textord_debug_tabfind)
PrintColumnCandidates("Column candidates");
// Improve the column candidates against themselves.
ImproveColumnCandidates(&column_sets_, &column_sets_);
if (textord_debug_tabfind)
PrintColumnCandidates("Improved columns");
// Improve the column candidates using the part_sets_.
ImproveColumnCandidates(&part_sets, &column_sets_);
}
ColPartitionSet* single_column_set =
part_grid_.MakeSingleColumnSet(WidthCB());
if (single_column_set != NULL) {
// Always add the single column set as a backup even if not in
// single column mode.
single_column_set->AddToColumnSetsIfUnique(&column_sets_, WidthCB());
}
if (textord_debug_tabfind)
PrintColumnCandidates("Final Columns");
bool has_columns = !column_sets_.empty();
if (has_columns) {
// Divide the page into sections of uniform column layout.
bool any_multi_column = AssignColumns(part_sets);
if (textord_tabfind_show_columns) {
DisplayColumnBounds(&part_sets);
}
ComputeMeanColumnGap(any_multi_column);
}
for (int i = 0; i < part_sets.size(); ++i) {
ColPartitionSet* line_set = part_sets.get(i);
if (line_set != NULL) {
line_set->RelinquishParts();
delete line_set;
}
}
return has_columns;
}
// Attempt to improve the column_candidates by expanding the columns
// and adding new partitions from the partition sets in src_sets.
// Src_sets may be equal to column_candidates, in which case it will
// use them as a source to improve themselves.
void ColumnFinder::ImproveColumnCandidates(PartSetVector* src_sets,
PartSetVector* column_sets) {
PartSetVector temp_cols;
temp_cols.move(column_sets);
if (src_sets == column_sets)
src_sets = &temp_cols;
int set_size = temp_cols.size();
// Try using only the good parts first.
bool good_only = true;
do {
for (int i = 0; i < set_size; ++i) {
ColPartitionSet* column_candidate = temp_cols.get(i);
ASSERT_HOST(column_candidate != NULL);
ColPartitionSet* improved = column_candidate->Copy(good_only);
if (improved != NULL) {
improved->ImproveColumnCandidate(WidthCB(), src_sets);
improved->AddToColumnSetsIfUnique(column_sets, WidthCB());
}
}
good_only = !good_only;
} while (column_sets->empty() && !good_only);
if (column_sets->empty())
column_sets->move(&temp_cols);
else
temp_cols.delete_data_pointers();
}
// Prints debug information on the column candidates.
void ColumnFinder::PrintColumnCandidates(const char* title) {
int set_size = column_sets_.size();
tprintf("Found %d %s:\n", set_size, title);
if (textord_debug_tabfind >= 3) {
for (int i = 0; i < set_size; ++i) {
ColPartitionSet* column_set = column_sets_.get(i);
column_set->Print();
}
}
}
// Finds the optimal set of columns that cover the entire image with as
// few changes in column partition as possible.
// NOTE: this could be thought of as an optimization problem, but a simple
// greedy algorithm is used instead. The algorithm repeatedly finds the modal
// compatible column in an unassigned region and uses that with the extra
// tweak of extending the modal region over small breaks in compatibility.
// Where modal regions overlap, the boundary is chosen so as to minimize
// the cost in terms of ColPartitions not fitting an approved column.
// Returns true if any part of the page is multi-column.
bool ColumnFinder::AssignColumns(const PartSetVector& part_sets) {
int set_count = part_sets.size();
ASSERT_HOST(set_count == gridheight());
// Allocate and init the best_columns_.
best_columns_ = new ColPartitionSet*[set_count];
for (int y = 0; y < set_count; ++y)
best_columns_[y] = NULL;
int column_count = column_sets_.size();
// column_set_costs[part_sets_ index][column_sets_ index] is
// < MAX_INT32 if the partition set is compatible with the column set,
// in which case its value is the cost for that set used in deciding
// which competing set to assign.
// any_columns_possible[part_sets_ index] is true if any of
// possible_column_sets[part_sets_ index][*] is < MAX_INT32.
// assigned_costs[part_sets_ index] is set to the column_set_costs
// of the assigned column_sets_ index or MAX_INT32 if none is set.
// On return the best_columns_ member is set.
bool* any_columns_possible = new bool[set_count];
int* assigned_costs = new int[set_count];
int** column_set_costs = new int*[set_count];
// Set possible column_sets to indicate whether each set is compatible
// with each column.
for (int part_i = 0; part_i < set_count; ++part_i) {
ColPartitionSet* line_set = part_sets.get(part_i);
bool debug = line_set != NULL &&
WithinTestRegion(2, line_set->bounding_box().left(),
line_set->bounding_box().bottom());
column_set_costs[part_i] = new int[column_count];
any_columns_possible[part_i] = false;
assigned_costs[part_i] = MAX_INT32;
for (int col_i = 0; col_i < column_count; ++col_i) {
if (line_set != NULL &&
column_sets_.get(col_i)->CompatibleColumns(debug, line_set,
WidthCB())) {
column_set_costs[part_i][col_i] =
column_sets_.get(col_i)->UnmatchedWidth(line_set);
any_columns_possible[part_i] = true;
} else {
column_set_costs[part_i][col_i] = MAX_INT32;
if (debug)
tprintf("Set id %d did not match at y=%d, lineset =%p\n",
col_i, part_i, line_set);
}
}
}
bool any_multi_column = false;
// Assign a column set to each vertical grid position.
// While there is an unassigned range, find its mode.
int start, end;
while (BiggestUnassignedRange(set_count, any_columns_possible,
&start, &end)) {
if (textord_debug_tabfind >= 2)
tprintf("Biggest unassigned range = %d- %d\n", start, end);
// Find the modal column_set_id in the range.
int column_set_id = RangeModalColumnSet(column_set_costs,
assigned_costs, start, end);
if (textord_debug_tabfind >= 2) {
tprintf("Range modal column id = %d\n", column_set_id);
column_sets_.get(column_set_id)->Print();
}
// Now find the longest run of the column_set_id in the range.
ShrinkRangeToLongestRun(column_set_costs, assigned_costs,
any_columns_possible,
column_set_id, &start, &end);
if (textord_debug_tabfind >= 2)
tprintf("Shrunk range = %d- %d\n", start, end);
// Extend the start and end past the longest run, while there are
// only small gaps in compatibility that can be overcome by larger
// regions of compatibility beyond.
ExtendRangePastSmallGaps(column_set_costs, assigned_costs,
any_columns_possible,
column_set_id, -1, -1, &start);
--end;
ExtendRangePastSmallGaps(column_set_costs, assigned_costs,
any_columns_possible,
column_set_id, 1, set_count, &end);
++end;
if (textord_debug_tabfind)
tprintf("Column id %d applies to range = %d - %d\n",
column_set_id, start, end);
// Assign the column to the range, which now may overlap with other ranges.
AssignColumnToRange(column_set_id, start, end, column_set_costs,
assigned_costs);
if (column_sets_.get(column_set_id)->GoodColumnCount() > 1)
any_multi_column = true;
}
// If anything remains unassigned, the whole lot is unassigned, so
// arbitrarily assign id 0.
if (best_columns_[0] == NULL) {
AssignColumnToRange(0, 0, gridheight_, column_set_costs, assigned_costs);
}
// Free memory.
for (int i = 0; i < set_count; ++i) {
delete [] column_set_costs[i];
}
delete [] assigned_costs;
delete [] any_columns_possible;
delete [] column_set_costs;
return any_multi_column;
}
// Finds the biggest range in part_sets_ that has no assigned column, but
// column assignment is possible.
bool ColumnFinder::BiggestUnassignedRange(int set_count,
const bool* any_columns_possible,
int* best_start, int* best_end) {
int best_range_size = 0;
*best_start = set_count;
*best_end = set_count;
int end = set_count;
for (int start = 0; start < gridheight_; start = end) {
// Find the first unassigned index in start.
while (start < set_count) {
if (best_columns_[start] == NULL && any_columns_possible[start])
break;
++start;
}
// Find the first past the end and count the good ones in between.
int range_size = 1; // Number of non-null, but unassigned line sets.
end = start + 1;
while (end < set_count) {
if (best_columns_[end] != NULL)
break;
if (any_columns_possible[end])
++range_size;
++end;
}
if (start < set_count && range_size > best_range_size) {
best_range_size = range_size;
*best_start = start;
*best_end = end;
}
}
return *best_start < *best_end;
}
// Finds the modal compatible column_set_ index within the given range.
int ColumnFinder::RangeModalColumnSet(int** column_set_costs,
const int* assigned_costs,
int start, int end) {
int column_count = column_sets_.size();
STATS column_stats(0, column_count);
for (int part_i = start; part_i < end; ++part_i) {
for (int col_j = 0; col_j < column_count; ++col_j) {
if (column_set_costs[part_i][col_j] < assigned_costs[part_i])
column_stats.add(col_j, 1);
}
}
ASSERT_HOST(column_stats.get_total() > 0);
return column_stats.mode();
}
// Given that there are many column_set_id compatible columns in the range,
// shrinks the range to the longest contiguous run of compatibility, allowing
// gaps where no columns are possible, but not where competing columns are
// possible.
void ColumnFinder::ShrinkRangeToLongestRun(int** column_set_costs,
const int* assigned_costs,
const bool* any_columns_possible,
int column_set_id,
int* best_start, int* best_end) {
// orig_start and orig_end are the maximum range we will look at.
int orig_start = *best_start;
int orig_end = *best_end;
int best_range_size = 0;
*best_start = orig_end;
*best_end = orig_end;
int end = orig_end;
for (int start = orig_start; start < orig_end; start = end) {
// Find the first possible
while (start < orig_end) {
if (column_set_costs[start][column_set_id] < assigned_costs[start] ||
!any_columns_possible[start])
break;
++start;
}
// Find the first past the end.
end = start + 1;
while (end < orig_end) {
if (column_set_costs[end][column_set_id] >= assigned_costs[start] &&
any_columns_possible[end])
break;
++end;
}
if (start < orig_end && end - start > best_range_size) {
best_range_size = end - start;
*best_start = start;
*best_end = end;
}
}
}
// Moves start in the direction of step, upto, but not including end while
// the only incompatible regions are no more than kMaxIncompatibleColumnCount
// in size, and the compatible regions beyond are bigger.
void ColumnFinder::ExtendRangePastSmallGaps(int** column_set_costs,
const int* assigned_costs,
const bool* any_columns_possible,
int column_set_id,
int step, int end, int* start) {
if (textord_debug_tabfind > 2)
tprintf("Starting expansion at %d, step=%d, limit=%d\n",
*start, step, end);
if (*start == end)
return; // Cannot be expanded.
int barrier_size = 0;
int good_size = 0;
do {
// Find the size of the incompatible barrier.
barrier_size = 0;
int i;
for (i = *start + step; i != end; i += step) {
if (column_set_costs[i][column_set_id] < assigned_costs[i])
break; // We are back on.
// Locations where none are possible don't count.
if (any_columns_possible[i])
++barrier_size;
}
if (textord_debug_tabfind > 2)
tprintf("At %d, Barrier size=%d\n", i, barrier_size);
if (barrier_size > kMaxIncompatibleColumnCount)
return; // Barrier too big.
if (i == end) {
// We can't go any further, but the barrier was small, so go to the end.
*start = i - step;
return;
}
// Now find the size of the good region on the other side.
good_size = 1;
for (i += step; i != end; i += step) {
if (column_set_costs[i][column_set_id] < assigned_costs[i])
++good_size;
else if (any_columns_possible[i])
break;
}
if (textord_debug_tabfind > 2)
tprintf("At %d, good size = %d\n", i, good_size);
// If we had enough good ones we can extend the start and keep looking.
if (good_size >= barrier_size)
*start = i - step;
} while (good_size >= barrier_size);
}
// Assigns the given column_set_id to the given range.
void ColumnFinder::AssignColumnToRange(int column_set_id, int start, int end,
int** column_set_costs,
int* assigned_costs) {
ColPartitionSet* column_set = column_sets_.get(column_set_id);
for (int i = start; i < end; ++i) {
assigned_costs[i] = column_set_costs[i][column_set_id];
best_columns_[i] = column_set;
}
}
// Computes the mean_column_gap_.
void ColumnFinder::ComputeMeanColumnGap(bool any_multi_column) {
int total_gap = 0;
int total_width = 0;
int gap_samples = 0;
int width_samples = 0;
for (int i = 0; i < gridheight_; ++i) {
ASSERT_HOST(best_columns_[i] != NULL);
best_columns_[i]->AccumulateColumnWidthsAndGaps(&total_width,
&width_samples,
&total_gap,
&gap_samples);
}
mean_column_gap_ = any_multi_column && gap_samples > 0
? total_gap / gap_samples : total_width / width_samples;
}
//////// Functions that manipulate ColPartitions in the part_grid_ /////
//////// to split, merge, find margins, and find types. //////////////
// Helper to delete all the deletable blobs on the list. Owned blobs are
// extracted from the list, but not deleted, leaving them owned by the owner().
static void ReleaseAllBlobsAndDeleteUnused(BLOBNBOX_LIST* blobs) {
for (BLOBNBOX_IT blob_it(blobs); !blob_it.empty(); blob_it.forward()) {
BLOBNBOX* blob = blob_it.extract();
if (blob->owner() == NULL) {
delete blob->cblob();
delete blob;
}
}
}
// Hoovers up all un-owned blobs and deletes them.
// The rest get released from the block so the ColPartitions can pass
// ownership to the output blocks.
void ColumnFinder::ReleaseBlobsAndCleanupUnused(TO_BLOCK* block) {
ReleaseAllBlobsAndDeleteUnused(&block->blobs);
ReleaseAllBlobsAndDeleteUnused(&block->small_blobs);
ReleaseAllBlobsAndDeleteUnused(&block->noise_blobs);
ReleaseAllBlobsAndDeleteUnused(&block->large_blobs);
ReleaseAllBlobsAndDeleteUnused(&image_bblobs_);
}
// Splits partitions that cross columns where they have nothing in the gap.
void ColumnFinder::GridSplitPartitions() {
// Iterate the ColPartitions in the grid.
GridSearch<ColPartition, ColPartition_CLIST, ColPartition_C_IT>
gsearch(&part_grid_);
gsearch.StartFullSearch();
ColPartition* dont_repeat = NULL;
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
if (part->blob_type() < BRT_UNKNOWN || part == dont_repeat)
continue; // Only applies to text partitions.
ColPartitionSet* column_set = best_columns_[gsearch.GridY()];
int first_col = -1;
int last_col = -1;
// Find which columns the partition spans.
part->ColumnRange(resolution_, column_set, &first_col, &last_col);
if (first_col > 0)
--first_col;
// Convert output column indices to physical column indices.
first_col /= 2;
last_col /= 2;
// We will only consider cases where a partition spans two columns,
// since a heading that spans more columns than that is most likely
// genuine.
if (last_col != first_col + 1)
continue;
// Set up a rectangle search x-bounded by the column gap and y by the part.
int y = part->MidY();
TBOX margin_box = part->bounding_box();
bool debug = AlignedBlob::WithinTestRegion(2, margin_box.left(),
margin_box.bottom());
if (debug) {
tprintf("Considering partition for GridSplit:");
part->Print();
}
ColPartition* column = column_set->GetColumnByIndex(first_col);
if (column == NULL)
continue;
margin_box.set_left(column->RightAtY(y) + 2);
column = column_set->GetColumnByIndex(last_col);
if (column == NULL)
continue;
margin_box.set_right(column->LeftAtY(y) - 2);
// TODO(rays) Decide whether to keep rectangular filling or not in the
// main grid and therefore whether we need a fancier search here.
// Now run the rect search on the main blob grid.
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> rectsearch(this);
if (debug) {
tprintf("Searching box (%d,%d)->(%d,%d)\n",
margin_box.left(), margin_box.bottom(),
margin_box.right(), margin_box.top());
part->Print();
}
rectsearch.StartRectSearch(margin_box);
BLOBNBOX* bbox;
while ((bbox = rectsearch.NextRectSearch()) != NULL) {
if (bbox->bounding_box().overlap(margin_box))
break;
}
if (bbox == NULL) {
// There seems to be nothing in the hole, so split the partition.
gsearch.RemoveBBox();
int x_middle = (margin_box.left() + margin_box.right()) / 2;
if (debug) {
tprintf("Splitting part at %d:", x_middle);
part->Print();
}
ColPartition* split_part = part->SplitAt(x_middle);
if (split_part != NULL) {
if (debug) {
tprintf("Split result:");
part->Print();
split_part->Print();
}
part_grid_.InsertBBox(true, true, split_part);
} else {
// Split had no effect
if (debug)
tprintf("Split had no effect\n");
dont_repeat = part;
}
part_grid_.InsertBBox(true, true, part);
gsearch.RepositionIterator();
} else if (debug) {
tprintf("Part cannot be split: blob (%d,%d)->(%d,%d) in column gap\n",
bbox->bounding_box().left(), bbox->bounding_box().bottom(),
bbox->bounding_box().right(), bbox->bounding_box().top());
}
}
}
// Merges partitions where there is vertical overlap, within a single column,
// and the horizontal gap is small enough.
void ColumnFinder::GridMergePartitions() {
// Iterate the ColPartitions in the grid.
GridSearch<ColPartition, ColPartition_CLIST, ColPartition_C_IT>
gsearch(&part_grid_);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
if (part->IsUnMergeableType())
continue;
// Set up a rectangle search x-bounded by the column and y by the part.
ColPartitionSet* columns = best_columns_[gsearch.GridY()];
TBOX box = part->bounding_box();
bool debug = AlignedBlob::WithinTestRegion(1, box.left(), box.bottom());
if (debug) {
tprintf("Considering part for merge at:");
part->Print();
}
int y = part->MidY();
ColPartition* left_column = columns->ColumnContaining(box.left(), y);
ColPartition* right_column = columns->ColumnContaining(box.right(), y);
if (left_column == NULL || right_column != left_column) {
if (debug)
tprintf("In different columns\n");
continue;
}
box.set_left(left_column->LeftAtY(y));
box.set_right(right_column->RightAtY(y));
// Now run the rect search.
bool modified_box = false;
GridSearch<ColPartition, ColPartition_CLIST, ColPartition_C_IT>
rsearch(&part_grid_);
rsearch.SetUniqueMode(true);
rsearch.StartRectSearch(box);
ColPartition* neighbour;
while ((neighbour = rsearch.NextRectSearch()) != NULL) {
if (neighbour == part || neighbour->IsUnMergeableType())
continue;
const TBOX& neighbour_box = neighbour->bounding_box();
if (debug) {
tprintf("Considering merge with neighbour at:");
neighbour->Print();
}
if (neighbour_box.right() < box.left() ||
neighbour_box.left() > box.right())
continue; // Not within the same column.
if (part->VSignificantCoreOverlap(*neighbour) &&
part->TypesMatch(*neighbour)) {
// There is vertical overlap and the gross types match, but only
// merge if the horizontal gap is small enough, as one of the
// partitions may be a figure caption within a column.
// If there is only one column, then the mean_column_gap_ is large
// enough to allow almost any merge, by being the mean column width.
const TBOX& part_box = part->bounding_box();
// Don't merge if there is something else in the way. Use the margin
// to decide, and check both to allow a bit of overlap.
if (neighbour_box.left() > part->right_margin() &&
part_box.right() < neighbour->left_margin())
continue; // Neighbour is too far to the right.
if (neighbour_box.right() < part->left_margin() &&
part_box.left() > neighbour->right_margin())
continue; // Neighbour is too far to the left.
int h_gap = MAX(part_box.left(), neighbour_box.left()) -
MIN(part_box.right(), neighbour_box.right());
if (h_gap < mean_column_gap_ * kHorizontalGapMergeFraction ||
part_box.width() < mean_column_gap_ ||
neighbour_box.width() < mean_column_gap_) {
if (debug) {
tprintf("Running grid-based merge between:\n");
part->Print();
neighbour->Print();
}
rsearch.RemoveBBox();
if (!modified_box) {
// We are going to modify part, so remove it and re-insert it after.
gsearch.RemoveBBox();
rsearch.RepositionIterator();
modified_box = true;
}
part->Absorb(neighbour, WidthCB());
} else if (debug) {
tprintf("Neighbour failed hgap test\n");
}
} else if (debug) {
tprintf("Neighbour failed overlap or typesmatch test\n");
}
}
if (modified_box) {
// We modified the box of part, so re-insert it into the grid.
// This does no harm in the current cell, as it already exists there,
// but it needs to exist in all the cells covered by its bounding box,
// or it will never be found by a full search.
// Because the box has changed, it has to be removed first, otherwise
// add_sorted may fail to keep a single copy of the pointer.
part_grid_.InsertBBox(true, true, part);
gsearch.RepositionIterator();
}
}
}
// Inserts remaining noise blobs into the most applicable partition if any.
// If there is no applicable partition, then the blobs are deleted.
void ColumnFinder::InsertRemainingNoise(TO_BLOCK* block) {
BLOBNBOX_IT blob_it(&block->noise_blobs);
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
BLOBNBOX* blob = blob_it.data();
if (blob->owner() != NULL) continue;
TBOX search_box(blob->bounding_box());
bool debug = WithinTestRegion(2, search_box.left(), search_box.bottom());
search_box.pad(gridsize(), gridsize());
// Setup a rectangle search to find the best partition to merge with.
ColPartitionGridSearch rsearch(&part_grid_);
rsearch.SetUniqueMode(true);
rsearch.StartRectSearch(search_box);
ColPartition* part;
ColPartition* best_part = NULL;
int best_distance = 0;
while ((part = rsearch.NextRectSearch()) != NULL) {
if (part->IsUnMergeableType())
continue;
int distance = projection_.DistanceOfBoxFromPartition(
blob->bounding_box(), *part, denorm_, debug);
if (best_part == NULL || distance < best_distance) {
best_part = part;
best_distance = distance;
}
}
if (best_part != NULL &&
best_distance < kMaxDistToPartSizeRatio * best_part->median_size()) {
// Close enough to merge.
if (debug) {
tprintf("Adding noise blob with distance %d, thr=%g:box:",
best_distance,
kMaxDistToPartSizeRatio * best_part->median_size());
blob->bounding_box().print();
tprintf("To partition:");
best_part->Print();
}
part_grid_.RemoveBBox(best_part);
best_part->AddBox(blob);
part_grid_.InsertBBox(true, true, best_part);
blob->set_owner(best_part);
blob->set_flow(best_part->flow());
blob->set_region_type(best_part->blob_type());
} else {
// Mark the blob for deletion.
blob->set_region_type(BRT_NOISE);
}
}
// Delete the marked blobs, clearing neighbour references.
block->DeleteUnownedNoise();
}
// Helper makes a box from a horizontal line.
static TBOX BoxFromHLine(const TabVector* hline) {
int top = MAX(hline->startpt().y(), hline->endpt().y());
int bottom = MIN(hline->startpt().y(), hline->endpt().y());
top += hline->mean_width();
if (top == bottom) {
if (bottom > 0)
--bottom;
else
++top;
}
return TBOX(hline->startpt().x(), bottom, hline->endpt().x(), top);
}
// Remove partitions that come from horizontal lines that look like
// underlines, but are not part of a table.
void ColumnFinder::GridRemoveUnderlinePartitions() {
TabVector_IT hline_it(&horizontal_lines_);
for (hline_it.mark_cycle_pt(); !hline_it.cycled_list(); hline_it.forward()) {
TabVector* hline = hline_it.data();
if (hline->intersects_other_lines())
continue;
TBOX line_box = BoxFromHLine(hline);
TBOX search_box = line_box;
search_box.pad(0, line_box.height());
ColPartitionGridSearch part_search(&part_grid_);
part_search.SetUniqueMode(true);
part_search.StartRectSearch(search_box);
ColPartition* covered;
bool touched_table = false;
bool touched_text = false;
ColPartition* line_part = NULL;
while ((covered = part_search.NextRectSearch()) != NULL) {
if (covered->type() == PT_TABLE) {
touched_table = true;
break;
} else if (covered->IsTextType()) {
// TODO(rays) Add a list of underline sections to ColPartition.
int text_bottom = covered->median_bottom();
if (line_box.bottom() <= text_bottom && text_bottom <= search_box.top())
touched_text = true;
} else if (covered->blob_type() == BRT_HLINE &&
line_box.contains(covered->bounding_box())) {
line_part = covered;
}
}
if (line_part != NULL && !touched_table && touched_text) {
part_grid_.RemoveBBox(line_part);
delete line_part;
}
}
}
// Add horizontal line separators as partitions.
void ColumnFinder::GridInsertHLinePartitions() {
TabVector_IT hline_it(&horizontal_lines_);
for (hline_it.mark_cycle_pt(); !hline_it.cycled_list(); hline_it.forward()) {
TabVector* hline = hline_it.data();
TBOX line_box = BoxFromHLine(hline);
ColPartition* part = ColPartition::MakeLinePartition(
BRT_HLINE, vertical_skew_,
line_box.left(), line_box.bottom(), line_box.right(), line_box.top());
part->set_type(PT_HORZ_LINE);
bool any_image = false;
ColPartitionGridSearch part_search(&part_grid_);
part_search.SetUniqueMode(true);
part_search.StartRectSearch(line_box);
ColPartition* covered;
while ((covered = part_search.NextRectSearch()) != NULL) {
if (covered->IsImageType()) {
any_image = true;
break;
}
}
if (!any_image)
part_grid_.InsertBBox(true, true, part);
else
delete part;
}
}
// Add horizontal line separators as partitions.
void ColumnFinder::GridInsertVLinePartitions() {
TabVector_IT vline_it(dead_vectors());
for (vline_it.mark_cycle_pt(); !vline_it.cycled_list(); vline_it.forward()) {
TabVector* vline = vline_it.data();
if (!vline->IsSeparator())
continue;
int left = MIN(vline->startpt().x(), vline->endpt().x());
int right = MAX(vline->startpt().x(), vline->endpt().x());
right += vline->mean_width();
if (left == right) {
if (left > 0)
--left;
else
++right;
}
ColPartition* part = ColPartition::MakeLinePartition(
BRT_VLINE, vertical_skew_,
left, vline->startpt().y(), right, vline->endpt().y());
part->set_type(PT_VERT_LINE);
bool any_image = false;
ColPartitionGridSearch part_search(&part_grid_);
part_search.SetUniqueMode(true);
part_search.StartRectSearch(part->bounding_box());
ColPartition* covered;
while ((covered = part_search.NextRectSearch()) != NULL) {
if (covered->IsImageType()) {
any_image = true;
break;
}
}
if (!any_image)
part_grid_.InsertBBox(true, true, part);
else
delete part;
}
}
// For every ColPartition in the grid, sets its type based on position
// in the columns.
void ColumnFinder::SetPartitionTypes() {
GridSearch<ColPartition, ColPartition_CLIST, ColPartition_C_IT>
gsearch(&part_grid_);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
part->SetPartitionType(resolution_, best_columns_[gsearch.GridY()]);
}
}
// Only images remain with multiple types in a run of partners.
// Sets the type of all in the group to the maximum of the group.
void ColumnFinder::SmoothPartnerRuns() {
// Iterate the ColPartitions in the grid.
GridSearch<ColPartition, ColPartition_CLIST, ColPartition_C_IT>
gsearch(&part_grid_);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
ColPartition* partner = part->SingletonPartner(true);
if (partner != NULL) {
if (partner->SingletonPartner(false) != part) {
tprintf("Ooops! Partition:(%d partners)",
part->upper_partners()->length());
part->Print();
tprintf("has singleton partner:(%d partners",
partner->lower_partners()->length());
partner->Print();
tprintf("but its singleton partner is:");
if (partner->SingletonPartner(false) == NULL)
tprintf("NULL\n");
else
partner->SingletonPartner(false)->Print();
}
ASSERT_HOST(partner->SingletonPartner(false) == part);
} else if (part->SingletonPartner(false) != NULL) {
ColPartitionSet* column_set = best_columns_[gsearch.GridY()];
int column_count = column_set->ColumnCount();
part->SmoothPartnerRun(column_count * 2 + 1);
}
}
}
// Helper functions for TransformToBlocks.
// Add the part to the temp list in the correct order.
void ColumnFinder::AddToTempPartList(ColPartition* part,
ColPartition_CLIST* temp_list) {
int mid_y = part->MidY();
ColPartition_C_IT it(temp_list);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* test_part = it.data();
if (part->type() == PT_NOISE || test_part->type() == PT_NOISE)
continue; // Noise stays in sequence.
if (test_part == part->SingletonPartner(false))
break; // Insert before its lower partner.
int neighbour_bottom = test_part->median_bottom();
int neighbour_top = test_part->median_top();
int neighbour_y = (neighbour_bottom + neighbour_top) / 2;
if (neighbour_y < mid_y)
break; // part is above test_part so insert it.
if (!part->HOverlaps(*test_part) && !part->WithinSameMargins(*test_part))
continue; // Incompatibles stay in order
}
if (it.cycled_list()) {
it.add_to_end(part);
} else {
it.add_before_stay_put(part);
}
}
// Add everything from the temp list to the work_set assuming correct order.
void ColumnFinder::EmptyTempPartList(ColPartition_CLIST* temp_list,
WorkingPartSet_LIST* work_set) {
ColPartition_C_IT it(temp_list);
while (!it.empty()) {
it.extract()->AddToWorkingSet(bleft_, tright_, resolution_,
&good_parts_, work_set);
it.forward();
}
}
// Transform the grid of partitions to the output blocks.
void ColumnFinder::TransformToBlocks(BLOCK_LIST* blocks,
TO_BLOCK_LIST* to_blocks) {
WorkingPartSet_LIST work_set;
ColPartitionSet* column_set = NULL;
ColPartition_IT noise_it(&noise_parts_);
// The temp_part_list holds a list of parts at the same grid y coord
// so they can be added in the correct order. This prevents thin objects
// like horizontal lines going before the text lines above them.
ColPartition_CLIST temp_part_list;
// Iterate the ColPartitions in the grid. It starts at the top
GridSearch<ColPartition, ColPartition_CLIST, ColPartition_C_IT>
gsearch(&part_grid_);
gsearch.StartFullSearch();
int prev_grid_y = -1;
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
int grid_y = gsearch.GridY();
if (grid_y != prev_grid_y) {
EmptyTempPartList(&temp_part_list, &work_set);
prev_grid_y = grid_y;
}
if (best_columns_[grid_y] != column_set) {
column_set = best_columns_[grid_y];
// Every line should have a non-null best column.
ASSERT_HOST(column_set != NULL);
column_set->ChangeWorkColumns(bleft_, tright_, resolution_,
&good_parts_, &work_set);
if (textord_debug_tabfind)
tprintf("Changed column groups at grid index %d, y=%d\n",
gsearch.GridY(), gsearch.GridY() * gridsize());
}
if (part->type() == PT_NOISE) {
noise_it.add_to_end(part);
} else {
AddToTempPartList(part, &temp_part_list);
}
}
EmptyTempPartList(&temp_part_list, &work_set);
// Now finish all working sets and transfer ColPartitionSets to block_sets.
WorkingPartSet_IT work_it(&work_set);
while (!work_it.empty()) {
WorkingPartSet* working_set = work_it.extract();
working_set->ExtractCompletedBlocks(bleft_, tright_, resolution_,
&good_parts_, blocks, to_blocks);
delete working_set;
work_it.forward();
}
}
// Helper reflects a list of blobs in the y-axis.
// Only reflects the BLOBNBOX bounding box. Not the blobs or outlines below.
static void ReflectBlobList(BLOBNBOX_LIST* bblobs) {
BLOBNBOX_IT it(bblobs);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
it.data()->reflect_box_in_y_axis();
}
}
// Reflect the blob boxes (but not the outlines) in the y-axis so that
// the blocks get created in the correct RTL order. Reflects the blobs
// in the input_block and the bblobs list.
// The reflection is undone in RotateAndReskewBlocks by
// reflecting the blocks themselves, and then recomputing the blob bounding
// boxes.
void ColumnFinder::ReflectForRtl(TO_BLOCK* input_block, BLOBNBOX_LIST* bblobs) {
ReflectBlobList(bblobs);
ReflectBlobList(&input_block->blobs);
ReflectBlobList(&input_block->small_blobs);
ReflectBlobList(&input_block->noise_blobs);
ReflectBlobList(&input_block->large_blobs);
// Update the denorm with the reflection.
DENORM* new_denorm = new DENORM;
new_denorm->SetupNormalization(NULL, NULL, denorm_,
0.0f, 0.0f, -1.0f, 1.0f, 0.0f, 0.0f);
denorm_ = new_denorm;
}
// Helper fixes up blobs and cblobs to match the desired rotation,
// exploding multi-outline blobs back to single blobs and accumulating
// the bounding box widths and heights.
static void RotateAndExplodeBlobList(const FCOORD& blob_rotation,
BLOBNBOX_LIST* bblobs,
STATS* widths,
STATS* heights) {
BLOBNBOX_IT it(bblobs);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
BLOBNBOX* blob = it.data();
C_BLOB* cblob = blob->cblob();
C_OUTLINE_LIST* outlines = cblob->out_list();
C_OUTLINE_IT ol_it(outlines);
if (!outlines->singleton()) {
// This blob has multiple outlines from CJK repair.
// Explode the blob back into individual outlines.
for (;!ol_it.empty(); ol_it.forward()) {
C_OUTLINE* outline = ol_it.extract();
BLOBNBOX* new_blob = BLOBNBOX::RealBlob(outline);
// This blob will be revisited later since we add_after_stay_put here.
// This means it will get rotated and have its width/height added to
// the stats below.
it.add_after_stay_put(new_blob);
}
it.extract();
delete cblob;
delete blob;
} else {
if (blob_rotation.x() != 1.0f || blob_rotation.y() != 0.0f) {
cblob->rotate(blob_rotation);
}
blob->compute_bounding_box();
widths->add(blob->bounding_box().width(), 1);
heights->add(blob->bounding_box().height(), 1);
}
}
}
// Undo the deskew that was done in FindTabVectors, as recognition is done
// without correcting blobs or blob outlines for skew.
// Reskew the completed blocks to put them back to the original rotated coords
// that were created by CorrectOrientation.
// If the input_is_rtl, then reflect the blocks in the y-axis to undo the
// reflection that was done before FindTabVectors.
// Blocks that were identified as vertical text (relative to the rotated
// coordinates) are further rotated so the text lines are horizontal.
// blob polygonal outlines are rotated to match the position of the blocks
// that they are in, and their bounding boxes are recalculated to be accurate.
// Record appropriate inverse transformations and required
// classifier transformation in the blocks.
void ColumnFinder::RotateAndReskewBlocks(bool input_is_rtl,
TO_BLOCK_LIST* blocks) {
if (input_is_rtl) {
// The skew is backwards because of the reflection.
FCOORD tmp = deskew_;
deskew_ = reskew_;
reskew_ = tmp;
}
TO_BLOCK_IT it(blocks);
int block_index = 1;
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
TO_BLOCK* to_block = it.data();
BLOCK* block = to_block->block;
// Blocks are created on the deskewed blob outlines in TransformToBlocks()
// so we need to reskew them back to page coordinates.
if (input_is_rtl) {
block->reflect_polygon_in_y_axis();
}
block->rotate(reskew_);
// Copy the right_to_left flag to the created block.
block->set_right_to_left(input_is_rtl);
// Save the skew angle in the block for baseline computations.
block->set_skew(reskew_);
block->set_index(block_index++);
FCOORD blob_rotation = ComputeBlockAndClassifyRotation(block);
// Rotate all the blobs if needed and recompute the bounding boxes.
// Compute the block median blob width and height as we go.
STATS widths(0, block->bounding_box().width());
STATS heights(0, block->bounding_box().height());
RotateAndExplodeBlobList(blob_rotation, &to_block->blobs,
&widths, &heights);
TO_ROW_IT row_it(to_block->get_rows());
for (row_it.mark_cycle_pt(); !row_it.cycled_list(); row_it.forward()) {
TO_ROW* row = row_it.data();
RotateAndExplodeBlobList(blob_rotation, row->blob_list(),
&widths, &heights);
}
block->set_median_size(static_cast<int>(widths.median() + 0.5),
static_cast<int>(heights.median() + 0.5));
if (textord_debug_tabfind >= 2)
tprintf("Block median size = (%d, %d)\n",
block->median_size().x(), block->median_size().y());
}
}
// Computes the rotations for the block (to make textlines horizontal) and
// for the blobs (for classification) and sets the appropriate members
// of the given block.
// Returns the rotation that needs to be applied to the blobs to make
// them sit in the rotated block.
FCOORD ColumnFinder::ComputeBlockAndClassifyRotation(BLOCK* block) {
// The text_rotation_ tells us the gross page text rotation that needs
// to be applied for classification
// TODO(rays) find block-level classify rotation by orientation detection.
// In the mean time, assume that "up" for text printed in the minority
// direction (PT_VERTICAL_TEXT) is perpendicular to the line of reading.
// Accomplish this by zero-ing out the text rotation. This covers the
// common cases of image credits in documents written in Latin scripts
// and page headings for predominantly vertically written CJK books.
FCOORD classify_rotation(text_rotation_);
FCOORD block_rotation(1.0f, 0.0f);
if (block->poly_block()->isA() == PT_VERTICAL_TEXT) {
// Vertical text needs to be 90 degrees rotated relative to the rest.
// If the rest has a 90 degree rotation already, use the inverse, making
// the vertical text the original way up. Otherwise use 90 degrees
// clockwise.
if (rerotate_.x() == 0.0f)
block_rotation = rerotate_;
else
block_rotation = FCOORD(0.0f, -1.0f);
block->rotate(block_rotation);
classify_rotation = FCOORD(1.0f, 0.0f);
}
block_rotation.rotate(rotation_);
// block_rotation is now what we have done to the blocks. Now do the same
// thing to the blobs, but save the inverse rotation in the block, as that
// is what we need to DENORM back to the image coordinates.
FCOORD blob_rotation(block_rotation);
block_rotation.set_y(-block_rotation.y());
block->set_re_rotation(block_rotation);
block->set_classify_rotation(classify_rotation);
if (textord_debug_tabfind) {
tprintf("Blk %d, type %d rerotation(%.2f, %.2f), char(%.2f,%.2f), box:",
block->index(), block->poly_block()->isA(),
block->re_rotation().x(), block->re_rotation().y(),
classify_rotation.x(), classify_rotation.y());
block->bounding_box().print();
}
return blob_rotation;
}
} // namespace tesseract.
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