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tesseract/textord/colfind.cpp
joregan 38a6b18a5f disable MSVC warning C4244 in a number of places to cut down the noise 
git-svn-id: https://tesseract-ocr.googlecode.com/svn/trunk@363 d0cd1f9f-072b-0410-8dd7-cf729c803f20
2010-05-26 10:22:27 +00:00

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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 "colfind.h"
#include "colpartition.h"
#include "colpartitionset.h"
#include "linefind.h"
#include "strokewidth.h"
#include "blobbox.h"
#include "scrollview.h"
#include "tessvars.h"
#include "varable.h"
#include "workingpartset.h"
namespace tesseract {
// Minimum width to be considered when making columns.
const int kMinColumnWidth = 100;
// When assigning columns, the max number of misfits that can be ignored.
const int kMaxIncompatibleColumnCount = 2;
// Max vertical distance of neighbouring ColPartition for it to be a partner.
const double kMaxPartitionSpacing = 1.75;
// 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;
// Search radius to use for finding large neighbours of smaller blobs.
const int kSmallBlobSearchRadius = 2;
BOOL_VAR(textord_tabfind_show_strokewidths, false, "Show stroke widths");
BOOL_VAR(textord_tabfind_show_initial_partitions,
false, "Show partition bounds");
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");
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,
TabVector_LIST* vlines, TabVector_LIST* hlines,
int vertical_x, int vertical_y)
: TabFind(gridsize, bleft, tright, vlines, vertical_x, vertical_y),
mean_column_gap_(tright.x() - bleft.x()),
global_median_xheight_(0), global_median_ledding_(0),
reskew_(1.0f, 0.0f), rerotate_(1.0f, 0.0f),
best_columns_(NULL) {
TabVector_IT h_it(&horizontal_lines_);
h_it.add_list_after(hlines);
}
// Templated helper function used to create destructor callbacks for the
// BBGrid::ClearGridData() method.
template <typename T> void DeleteObject(T *object) {
delete object;
}
ColumnFinder::~ColumnFinder() {
column_sets_.delete_data_pointers();
if (best_columns_ != NULL) {
delete [] best_columns_;
}
// ColPartitions and ColSegments created by this class for storage in grids
// need to be deleted explicitly.
clean_part_grid_.ClearGridData(&DeleteObject<ColPartition>);
col_seg_grid_.ClearGridData(&DeleteObject<ColSegment>);
// 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();
}
}
// Finds the text and image blocks, returning them in the blocks and to_blocks
// lists. (Each TO_BLOCK points to the basic BLOCK and adds more information.)
// If boxa and pixa are not NULL, they are assumed to be the output of
// ImageFinder::FindImages, and are used to generate image blocks.
// The input boxa and pixa are destroyed.
// Imageheight and resolution should be the pixel height and resolution in
// pixels per inch of the original image.
// The input block is the result of a call to find_components, and contains
// the blobs found in the image. 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.
// Returns -1 if the user requested retry with more debug info.
int ColumnFinder::FindBlocks(int imageheight, int resolution,
bool single_column, TO_BLOCK* block,
Boxa* boxa, Pixa* pixa,
BLOCK_LIST* blocks, TO_BLOCK_LIST* to_blocks) {
#ifdef HAVE_LIBLEPT
if (boxa != NULL) {
// Convert the boxa/pixa to fake blobs aligned on the grid.
ExtractImageBlobs(imageheight, boxa, pixa);
boxaDestroy(&boxa);
pixaDestroy(&pixa);
}
#endif
// Decide which large blobs should be included in the grid as potential
// characters.
// A subsidiary grid used to decide which large blobs to use.
StrokeWidth* stroke_width = new StrokeWidth(gridsize(), bleft(), tright());
stroke_width->InsertBlobs(block, this);
if (textord_tabfind_show_strokewidths) {
stroke_width->DisplayGoodBlobs("GoodStrokewidths", NULL);
}
stroke_width->MoveGoodLargeBlobs(resolution, block);
delete stroke_width;
if (single_column) {
// No tab stops needed. Just the grid that FindTabVectors makes.
DontFindTabVectors(resolution, &image_bblobs_, block, &reskew_);
} else {
// Find the tab stops.
FindTabVectors(resolution, &horizontal_lines_, &image_bblobs_, block,
&reskew_, &rerotate_);
}
// Find the columns.
if (MakeColumnPartitions() == 0)
return 0; // This is an empty page.
// Make the initial column candidates from the part_sets_.
MakeColumnCandidates(single_column);
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_);
if (textord_debug_tabfind)
PrintColumnCandidates("Final Columns");
// Divide the page into sections of uniform column layout.
AssignColumns();
if (textord_tabfind_show_columns) {
DisplayColumnBounds(&part_sets_);
}
ComputeMeanColumnGap();
// Refill the grid using rectangular spreading, and get the benefit
// of the completed tab vectors marking the rule edges of each blob.
Clear();
InsertBlobList(false, false, false, &image_bblobs_, true, this);
InsertBlobList(true, true, false, &block->blobs, true, this);
// Insert all the remaining small and noise blobs into the grid and also
// make an unknown partition for each. Ownership is taken by the grid.
InsertSmallBlobsAsUnknowns(true, &block->small_blobs);
InsertSmallBlobsAsUnknowns(true, &block->noise_blobs);
// 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,
// but they both gave up ownership to the grid at the InsertBlobList above.)
MovePartitionsToGrid();
// 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.
GridFindMargins();
ListFindMargins(&unknown_parts_);
GridInsertUnknowns();
GridMergePartitions();
// Add horizontal line separators as partitions.
GridInsertHLinePartitions();
// Recompute margins based on a local neighbourhood search.
GridFindMargins();
SetPartitionTypes();
if (textord_tabfind_show_initial_partitions) {
ScrollView* part_win = MakeWindow(100, 300, "InitialPartitions");
part_grid_.DisplayBoxes(part_win);
DisplayTabVectors(part_win);
}
// Copy cleaned partitions from part_grid_ to clean_part_grid_ and
// insert dot-like noise into period_grid_
GetCleanPartitions(block);
// Get Table Regions
LocateTables();
// 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.
FindPartitionPartners();
RefinePartitionPartners();
SmoothPartnerRuns();
if (textord_tabfind_show_partitions) {
ScrollView* window = MakeWindow(400, 300, "Partitions");
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);
}
}
part_grid_.AssertNoDuplicates();
// 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.
TransformToBlocks(blocks, to_blocks);
if (textord_debug_tabfind) {
tprintf("Found %d blocks, %d to_blocks\n",
blocks->length(), to_blocks->length());
}
DisplayBlocks(blocks);
// MoveSmallBlobs(&block->small_blobs, to_blocks);
// MoveSmallBlobs(&block->noise_blobs, to_blocks);
// MoveSmallBlobs(&period_blobs_, to_blocks);
RotateAndReskewBlocks(to_blocks);
int result = 0;
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);
}
return result;
}
//////////////// 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
}
// Converts the arrays of Box/Pix to a list of C_OUTLINE, and then to blobs.
// The output is a list of C_BLOBs for the images, but the C_OUTLINEs
// contain no data.
void ColumnFinder::ExtractImageBlobs(int image_height, Boxa* boxa, Pixa* pixa) {
#ifdef HAVE_LIBLEPT
BLOBNBOX_IT bb_it(&image_bblobs_);
// Iterate the connected components in the image regions mask.
int nboxes = boxaGetCount(boxa);
for (int i = 0; i < nboxes; ++i) {
l_int32 x, y, width, height;
boxaGetBoxGeometry(boxa, i, &x, &y, &width, &height);
Pix* pix = pixaGetPix(pixa, i, L_CLONE);
// Special case set in FindImages:
// The image is a rectangle if its width doesn't match the box width.
bool rectangle = width != pixGetWidth(pix);
// For each grid cell in the pix, find the bounding box of the black
// pixels within the cell.
int grid_xmin, grid_ymin, grid_xmax, grid_ymax;
GridCoords(x, image_height - (y + height), &grid_xmin, &grid_ymin);
GridCoords(x + width - 1, image_height - 1 - y, &grid_xmax, &grid_ymax);
for (int grid_y = grid_ymin; grid_y <= grid_ymax; ++grid_y) {
for (int grid_x = grid_xmin; grid_x <= grid_xmax; ++grid_x) {
// Compute bounds of grid cell in sub-image.
int x_start = grid_x * gridsize_ + bleft_.x() - x;
int y_end = image_height - (grid_y * gridsize_ + bleft_.y()) - y;
int x_end = x_start + gridsize_;
int y_start = y_end - gridsize_;
ImageFinder::BoundsWithinRect(pix, &x_start, &y_start, &x_end, &y_end);
// If the box is not degenerate, make a blob.
if (x_end > x_start && y_end > y_start) {
C_OUTLINE_LIST outlines;
C_OUTLINE_IT ol_it = &outlines;
// Make a C_OUTLINE from the bounds. This is a bit of a hack,
// as there is no outline, just a bounding box, but with some very
// small changes to coutln.cpp, it works nicely.
ICOORD top_left(x_start + x, image_height - (y_start + y));
ICOORD bot_right(x_end + x, image_height - (y_end + y));
CRACKEDGE startpt;
startpt.pos = top_left;
C_OUTLINE* outline = new C_OUTLINE(&startpt, top_left, bot_right, 0);
ol_it.add_after_then_move(outline);
C_BLOB* blob = new C_BLOB(&outlines);
// Although a BLOBNBOX doesn't normally think it owns the blob,
// these will all end up in a ColPartition, which deletes the
// C_BLOBs of all its BLOBNBOXes in its destructor to match the
// fact that the rest get moved to a block later.
BLOBNBOX* bblob = new BLOBNBOX(blob);
bblob->set_region_type(rectangle ? BRT_RECTIMAGE : BRT_POLYIMAGE);
bb_it.add_after_then_move(bblob);
}
}
}
pixDestroy(&pix);
}
#endif // HAVE_LIBLEPT
}
////// Functions involved in making the initial ColPartitions. /////
// Creates the initial ColPartitions, and puts them in a ColPartitionSet
// for each grid y coordinate, storing the ColPartitionSets in part_sets_.
// After creating the ColPartitonSets, attempts to merge them where they
// overlap and unique the BLOBNBOXes within.
// The return value is the number of ColPartitionSets made.
int ColumnFinder::MakeColumnPartitions() {
part_sets_.reserve(gridheight_);
for (int grid_y = 0; grid_y < gridheight_; ++grid_y) {
ColPartitionSet* line_set = PartitionsAtGridY(grid_y);
part_sets_.push_back(line_set);
}
// Now merge neighbouring partitions that overlap significantly.
int part_set_count = 0;
for (int i = 0; i < gridheight_; ++i) {
ColPartitionSet* line_set = part_sets_.get(i);
if (line_set == NULL)
continue;
bool merged_any = false;
for (int j = i + 1; j < gridheight_; ++j) {
ColPartitionSet* line_set2 = part_sets_.get(j);
if (line_set2 == NULL)
continue;
if (line_set->MergeOverlaps(line_set2, WidthCB())) {
merged_any = true;
if (line_set2->Empty()) {
delete line_set2;
part_sets_.set(NULL, j);
}
if (line_set->Empty()) {
delete line_set;
part_sets_.set(NULL, i);
merged_any = false;
break;
}
} else {
break;
}
}
if (merged_any)
--i; // Try this one again.
else
++part_set_count;
}
return part_set_count;
}
// Partition the BLOBNBOXES horizontally at the given grid y, creating a
// ColPartitionSet which is returned. NULL is returned if there are no
// BLOBNBOXES at the given grid y.
ColPartitionSet* ColumnFinder::PartitionsAtGridY(int grid_y) {
ColPartition_LIST partitions;
ColPartition_IT part_it(&partitions);
// Setup a search of all the grid cells at the given y.
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> rectsearch(this);
int y = grid_y * gridsize_ + bleft_.y();
ICOORD botleft(bleft_.x(), y);
ICOORD topright(tright_.x(), y + gridsize_ - 1);
TBOX line_box(botleft, topright);
rectsearch.StartRectSearch(line_box);
BLOBNBOX* bbox = rectsearch.NextRectSearch();
// Each iteration round this while loop finds a set of boxes between
// tabvectors (or a change of aligned_text type) and places them in
// a ColPartition.
int page_edge = line_box.right() + kColumnWidthFactor;
int prev_margin = line_box.left() - kColumnWidthFactor;
// Runs of unknown blobs (not certainly text or image) go in a special
// unk_part, following the same rules as known blobs, but need a
// separate set of variables to hold the margin/edge information.
ColPartition_IT unk_part_it(&unknown_parts_);
ColPartition* unk_partition = NULL;
TabVector* unk_right_line = NULL;
int unk_right_margin = page_edge;
int unk_prev_margin = prev_margin;
bool unk_edge_is_left = false;
while (bbox != NULL) {
TBOX box = bbox->bounding_box();
if (WithinTestRegion(2, box.left(), box.bottom()))
tprintf("Starting partition on grid y=%d with box (%d,%d)->(%d,%d)\n",
grid_y, box.left(), box.bottom(), box.right(), box.top());
if (box.left() < prev_margin + 1 && textord_debug_bugs) {
tprintf("Starting box too far left at %d vs %d:",
box.left(), prev_margin + 1);
part_it.data()->Print();
}
int right_margin = page_edge;
BlobRegionType start_type = bbox->region_type();
if (start_type == BRT_NOISE) {
// Ignore blobs that have been overruled by image blobs.
// TODO(rays) Possible place to fix inverse text.
bbox = rectsearch.NextRectSearch();
continue;
}
if (start_type == BRT_UNKNOWN) {
// Keep unknown blobs in a special partition.
ProcessUnknownBlob(page_edge, bbox, &unk_partition, &unk_part_it,
&unk_right_line, &unk_right_margin,
&unk_prev_margin, &unk_edge_is_left);
bbox = rectsearch.NextRectSearch();
continue;
}
if (unk_partition != NULL)
unk_prev_margin = CompletePartition(false, page_edge,
unk_right_line, &unk_right_margin,
&unk_partition, &unk_part_it);
TabVector* right_line = NULL;
bool edge_is_left = false;
ColPartition* partition = StartPartition(start_type, prev_margin + 1, bbox,
&right_line, &right_margin,
&edge_is_left);
// Search for the right edge of this partition.
while ((bbox = rectsearch.NextRectSearch()) != NULL) {
TBOX box = bbox->bounding_box();
int left = box.left();
int right = box.right();
int edge = edge_is_left ? left : right;
BlobRegionType next_type = bbox->region_type();
if (next_type == BRT_NOISE)
continue;
if (next_type == BRT_UNKNOWN) {
// Keep unknown blobs in a special partition.
ProcessUnknownBlob(page_edge, bbox, &unk_partition, &unk_part_it,
&unk_right_line, &unk_right_margin,
&unk_prev_margin, &unk_edge_is_left);
continue; // Deal with them later.
}
if (unk_partition != NULL)
unk_prev_margin = CompletePartition(false, page_edge,
unk_right_line, &unk_right_margin,
&unk_partition, &unk_part_it);
if (ColPartition::TypesMatch(next_type, start_type) &&
edge < right_margin) {
// Still within the region and it is still the same type.
partition->AddBox(bbox);
} else {
// This is the first blob in the next set. It gives us the absolute
// max right coord of the block. (The right margin.)
right_margin = left - 1;
if (WithinTestRegion(2, box.left(), box.bottom()))
tprintf("Box (%d,%d)->(%d,%d) ended partition at %d\n",
box.left(), box.bottom(), box.right(), box.top(),
right_margin);
break;
}
}
prev_margin = CompletePartition(bbox == NULL, page_edge,
right_line, &right_margin,
&partition, &part_it);
}
if (unk_partition != NULL)
CompletePartition(true, page_edge, unk_right_line, &unk_right_margin,
&unk_partition, &unk_part_it);
return partitions.empty() ? NULL : new ColPartitionSet(&partitions);
}
// Insert the blobs in the given list into the main grid and for
// each one also make it a separate unknown partition.
// If filter is true, use only the blobs that are above a threshold in
// size or a non-isolated.
void ColumnFinder::InsertSmallBlobsAsUnknowns(bool filter,
BLOBNBOX_LIST* blobs) {
double noise_blob_size = gridsize() * kMinNonNoiseFraction;
ColPartition_IT unk_part_it(&unknown_parts_);
BLOBNBOX_IT blob_it(blobs);
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
BLOBNBOX* blob = blob_it.data();
TBOX box = blob->bounding_box();
bool good_blob = !filter ||
box.width() > noise_blob_size ||
box.height() > noise_blob_size;
if (!good_blob) {
// Search the vicinity for a bigger blob.
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> radsearch(this);
radsearch.StartRadSearch((box.left() + box.right()) / 2,
(box.bottom() + box.top()) / 2,
kSmallBlobSearchRadius);
BLOBNBOX* neighbour;
while ((neighbour = radsearch.NextRadSearch()) != NULL) {
TBOX nbox = neighbour->bounding_box();
// Neighbours must be bigger than the noise size limit to prevent
// the seed effect of starting with one noise object near a real
// object, and it then allowing all its neighbours to be accepted.
if (nbox.height() > noise_blob_size || nbox.width() > noise_blob_size)
break;
}
if (neighbour != NULL)
good_blob = true;
}
if (good_blob) {
blob_it.extract();
blob->set_noise_flag(true);
InsertBlob(true, true, false, blob, this);
if (WithinTestRegion(2, box.left(), box.bottom()))
tprintf("Starting small partition with box (%d,%d)->(%d,%d)\n",
box.left(), box.bottom(), box.right(), box.top());
int unk_right_margin = tright().x();
TabVector* unk_right_line = NULL;
bool unk_edge_is_left = false;
ColPartition* unk_partition = StartPartition(BRT_TEXT, bleft().x(), blob,
&unk_right_line,
&unk_right_margin,
&unk_edge_is_left);
CompletePartition(false, tright().x(), unk_right_line,
&unk_right_margin, &unk_partition, &unk_part_it);
}
}
}
// Helper function for PartitionsAtGridY, with a long argument list.
// This bbox is of unknown type, so it is added to an unk_partition.
// If the edge is past the unk_right_margin then unk_partition has to be
// completed and a new one made. See CompletePartition and StartPartition
// for the other args.
void ColumnFinder::ProcessUnknownBlob(int page_edge,
BLOBNBOX* bbox,
ColPartition** unk_partition,
ColPartition_IT* unk_part_it,
TabVector** unk_right_line,
int* unk_right_margin,
int* unk_prev_margin,
bool* unk_edge_is_left) {
if (*unk_partition != NULL) {
const TBOX& box = bbox->bounding_box();
int edge = *unk_edge_is_left ? box.left() : box.right();
if (edge >= *unk_right_margin)
*unk_prev_margin = CompletePartition(false, page_edge,
*unk_right_line, unk_right_margin,
unk_partition, unk_part_it);
}
if (*unk_partition == NULL) {
*unk_partition = StartPartition(BRT_TEXT, *unk_prev_margin + 1, bbox,
unk_right_line,
unk_right_margin,
unk_edge_is_left);
} else {
(*unk_partition)->AddBox(bbox);
}
}
// Creates and returns a new ColPartition of the given start_type
// and adds the given bbox to it.
// Also finds the left and right tabvectors that bound the textline, setting
// the members of the returned ColPartition appropriately:
// If the left tabvector is less constraining than the input left_margin
// (assumed to be the right edge of the previous partition), then the
// tabvector is ignored and the left_margin used instead.
// If the right tabvector is more constraining than the input *right_margin,
// (probably the right edge of the page), then the *right_margin is adjusted
// to use the tabvector.
// *edge_is_left is set to true if the right tabvector is good and used as the
// margin, so we can include blobs that overhang the tabvector in this
// partition.
ColPartition* ColumnFinder::StartPartition(BlobRegionType start_type,
int left_margin, BLOBNBOX* bbox,
TabVector** right_line,
int* right_margin,
bool* edge_is_left) {
ColPartition* partition = new ColPartition(start_type, vertical_skew_);
partition->AddBox(bbox);
// Find the tabs that bound it.
TBOX box = bbox->bounding_box();
int mid_y = (box.bottom() + box.top()) / 2;
TabVector* left_line = LeftTabForBox(box, true, false);
// If the overlapping line is not a left tab, try for non-overlapping.
if (left_line != NULL && !left_line->IsLeftTab())
left_line = LeftTabForBox(box, false, false);
if (left_line != NULL) {
int left_x = left_line->XAtY(mid_y);
left_x += left_line->IsLeftTab() ? -kColumnWidthFactor : 1;
// If the left line is not a genuine left or is less constraining
// than the previous blob, then don't store it in the partition.
if (left_x < left_margin || !left_line->IsLeftTab())
left_line = NULL;
if (left_x > left_margin)
left_margin = left_x;
if (WithinTestRegion(2, box.left(), box.bottom()))
tprintf("Left x =%d, left margin = %d\n",
left_x, left_margin);
}
partition->set_left_margin(left_margin);
*right_line = RightTabForBox(box, true, false);
// If the overlapping line is not a right tab, try for non-overlapping.
if (*right_line != NULL && !(*right_line)->IsRightTab())
*right_line = RightTabForBox(box, false, false);
*edge_is_left = false;
if (*right_line != NULL) {
int right_x = (*right_line)->XAtY(box.bottom());
if (right_x < *right_margin) {
*right_margin = right_x;
if ((*right_line)->IsRightTab())
*edge_is_left = true;
}
if (WithinTestRegion(3, box.left(), box.bottom()))
tprintf("Right x =%d, right_max = %d\n",
right_x, *right_margin);
}
partition->set_right_margin(*right_margin);
partition->ComputeLimits();
partition->SetLeftTab(left_line);
partition->SetRightTab(*right_line);
return partition;
}
// Completes the given partition, and adds it to the given iterator.
// The right_margin on input is the left edge of the next blob if there is
// one. The right tab vector plus a margin is used as the right margin if
// it is more constraining than the next blob, but if there are no more
// blobs, we want the right margin to make it to the page edge.
// The return value is the next left margin, being the right edge of the
// bounding box of blobs.
int ColumnFinder::CompletePartition(bool no_more_blobs,
int page_edge,
TabVector* right_line,
int* right_margin,
ColPartition** partition,
ColPartition_IT* part_it) {
ASSERT_HOST(partition !=NULL && *partition != NULL);
// If we have a right line, it is possible that its edge is more
// constraining than the next blob.
if (right_line != NULL && right_line->IsRightTab()) {
int mid_y = (*partition)->MidY();
int right_x = right_line->XAtY(mid_y) + kColumnWidthFactor;
if (right_x < *right_margin)
*right_margin = right_x;
else if (no_more_blobs)
*right_margin = MAX(right_x, page_edge);
else if (right_line->XAtY(mid_y) > *right_margin)
right_line = NULL;
} else {
right_line = NULL;
}
// Now we can complete the partition and add it to the list.
(*partition)->set_right_margin(*right_margin);
(*partition)->ComputeLimits();
(*partition)->SetRightTab(right_line);
(*partition)->SetColumnGoodness(WidthCB());
part_it->add_after_then_move(*partition);
// Setup ready to start the next one.
*right_margin = page_edge;
int next_left_margin = (*partition)->bounding_box().right();
*partition = NULL;
return next_left_margin;
}
// Makes an ordered list of candidates to partition the width of the page
// into columns using the part_sets_.
// See AddToColumnSetsIfUnique for the ordering.
// If single_column, then it just makes a single page-wide fake column.
void ColumnFinder::MakeColumnCandidates(bool single_column) {
if (!single_column) {
// 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 (column_sets_.empty()) {
// The page contains only image or is single column.
// Make a fake page-wide column.
ColPartition* fake_part = new ColPartition(BRT_TEXT, vertical_skew_);
fake_part->set_left_margin(bleft_.x());
fake_part->set_right_margin(tright_.x());
fake_part->ComputeLimits();
fake_part->SetColumnGoodness(WidthCB());
ColPartitionSet* column_candidate = new ColPartitionSet(fake_part);
column_candidate->AddToColumnSetsIfUnique(&column_sets_, WidthCB());
}
}
// 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.
void ColumnFinder::AssignColumns() {
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();
// possible_column_sets[part_sets_ index][column_sets_ index] is
// true if the partition set is compatible with the column set.
// assigned_column_sets[part_sets_ index][column_sets_ index] is true
// if the partition set has been assigned the column. (Multiple bits
// true is possible.)
// any_columns_possible[part_sets_ index] is true if any of
// possible_column_sets[part_sets_ index][*] is true.
// On return the best_columns_ member is set.
bool* any_columns_possible = new bool[set_count];
bool** possible_column_sets = new bool*[set_count];
bool** assigned_column_sets = new bool*[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());
possible_column_sets[part_i] = new bool[column_count];
assigned_column_sets[part_i] = new bool[column_count];
any_columns_possible[part_i] = false;
for (int col_i = 0; col_i < column_count; ++col_i) {
assigned_column_sets[part_i][col_i] = false;
if (line_set != NULL &&
column_sets_.get(col_i)->CompatibleColumns(debug, line_set,
WidthCB())) {
possible_column_sets[part_i][col_i] = true;
any_columns_possible[part_i] = true;
} else {
possible_column_sets[part_i][col_i] = false;
}
}
}
// Assign a column set to each vertical grid position.
// While there is an unassigned range, find its mode.
int start, end;
while (BiggestUnassignedRange(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(possible_column_sets, 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(possible_column_sets, 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(possible_column_sets, any_columns_possible,
column_set_id, -1, -1, &start);
--end;
ExtendRangePastSmallGaps(possible_column_sets, 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,
assigned_column_sets);
}
// If anything remains unassigned, the whole lot is unassigned, so
// arbitrarily assign id 0.
if (best_columns_[0] == NULL) {
AssignColumnToRange(0, 0, gridheight_, assigned_column_sets);
}
// Free memory.
for (int i = 0; i < set_count; ++i) {
delete [] possible_column_sets[i];
delete [] assigned_column_sets[i];
}
delete [] any_columns_possible;
delete [] possible_column_sets;
delete [] assigned_column_sets;
// TODO(rays) Now resolve overlapping assignments.
}
// Finds the biggest range in part_sets_ that has no assigned column, but
// column assignment is possible.
bool ColumnFinder::BiggestUnassignedRange(const bool* any_columns_possible,
int* best_start, int* best_end) {
int set_count = part_sets_.size();
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(bool** possible_column_sets,
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 (possible_column_sets[part_i][col_j])
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(bool** possible_column_sets,
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 (possible_column_sets[start][column_set_id] ||
!any_columns_possible[start])
break;
++start;
}
// Find the first past the end.
end = start + 1;
while (end < orig_end) {
if (!possible_column_sets[end][column_set_id] &&
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(bool** possible_column_sets,
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 (possible_column_sets[i][column_set_id])
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 (possible_column_sets[i][column_set_id])
++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,
bool** assigned_column_sets) {
ColPartitionSet* column_set = column_sets_.get(column_set_id);
for (int i = start; i < end; ++i) {
assigned_column_sets[i][column_set_id] = true;
best_columns_[i] = column_set;
}
}
// Computes the mean_column_gap_.
void ColumnFinder::ComputeMeanColumnGap() {
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_ = 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. //////////////
// Removes the ColPartitions from part_sets_, the ColPartitionSets that
// contain them, and puts them in the part_grid_ after ensuring that no
// BLOBNBOX is owned by more than one of them.
void ColumnFinder::MovePartitionsToGrid() {
// Remove the parts from the part_sets_ and put them in the parts list.
part_grid_.Init(gridsize(), bleft(), tright());
ColPartition_LIST parts;
for (int i = 0; i < gridheight_; ++i) {
ColPartitionSet* line_set = part_sets_.get(i);
if (line_set != NULL) {
line_set->ReturnParts(&parts);
delete line_set;
part_sets_.set(NULL, i);
}
}
// Make each part claim ownership of its own boxes uniquely.
ColPartition_IT it(&parts);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* part = it.data();
part->ClaimBoxes(WidthCB());
}
// Unknowns must be uniqued too.
it.set_to_list(&unknown_parts_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* part = it.data();
part->ClaimBoxes(WidthCB());
}
// Put non-empty parts into the grid and delete empty ones.
for (it.set_to_list(&parts); !it.empty(); it.forward()) {
ColPartition* part = it.extract();
if (part->IsEmpty())
delete part;
else
part_grid_.InsertBBox(true, true, part);
}
}
// 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(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;
if (textord_debug_tabfind) {
tprintf("Considering partition for GridSplit:");
part->Print();
}
// 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();
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 (textord_debug_tabfind) {
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 (textord_debug_tabfind) {
tprintf("Splitting part at %d:", x_middle);
part->Print();
}
ColPartition* split_part = part->SplitAt(x_middle);
if (split_part != NULL) {
if (textord_debug_tabfind) {
tprintf("Split result:");
part->Print();
split_part->Print();
}
part_grid_.InsertBBox(true, true, split_part);
} else {
// Split had no effect
if (textord_debug_tabfind)
tprintf("Split had no effect\n");
dont_repeat = part;
}
part_grid_.InsertBBox(true, true, part);
gsearch.RepositionIterator();
} else if (textord_debug_tabfind) {
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) {
// 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();
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)
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.StartRectSearch(box);
ColPartition* neighbour;
while ((neighbour = rsearch.NextRectSearch()) != NULL) {
if (neighbour == part)
continue;
const TBOX& neighbour_box = neighbour->bounding_box();
if (neighbour_box.right() < box.left() ||
neighbour_box.left() > box.right())
continue; // Not within the same column.
if (part->VOverlaps(*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();
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 (textord_debug_tabfind) {
tprintf("Running grid-based merge between:\n");
part->Print();
neighbour->Print();
}
rsearch.RemoveBBox();
gsearch.RepositionIterator();
part->Absorb(neighbour, WidthCB());
modified_box = true;
}
}
}
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.
gsearch.RemoveBBox();
part_grid_.InsertBBox(true, true, part);
gsearch.RepositionIterator();
}
}
}
// Helper function to compute the total pairwise area overlap of a list of
// Colpartitions. If box_this matches an element in the list, the test_box
// is used in place of its box.
static int TotalPairwiseOverlap(const ColPartition* box_this,
const TBOX& test_box,
ColPartition_CLIST* parts) {
if (parts->singleton())
return 0;
int total_area = 0;
for (ColPartition_C_IT it(parts); !it.at_last(); it.forward()) {
ColPartition* part = it.data();
TBOX part_box = part == box_this ? test_box : part->bounding_box();
ColPartition_C_IT it2(it);
for (it2.forward(); !it2.at_first(); it2.forward()) {
ColPartition* part2 = it2.data();
TBOX part_box2 = part2 == box_this ? test_box : part2->bounding_box();
total_area += part_box.intersection(part_box2).area();
}
}
return total_area;
}
// Helper function to compute the total area of a list of Colpartitions.
// If box_this matches an element in the list, the test_box
// is used in place of its box.
static int TotalArea(const ColPartition* box_this, const TBOX& test_box,
ColPartition_CLIST* parts) {
int total_area = 0;
ColPartition_C_IT it(parts);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* part = it.data();
TBOX part_box = part == box_this ? test_box : part->bounding_box();
total_area += part_box.area();
}
return total_area;
}
// Resolves unknown partitions from the unknown_parts_ list by merging them
// with a close neighbour, inserting them into the grid with a known type,
// or declaring them to be noise.
void ColumnFinder::GridInsertUnknowns() {
ColPartition_IT noise_it(&noise_parts_);
for (ColPartition_IT it(&unknown_parts_); !it.empty(); it.forward()) {
ColPartition* part = it.extract();
if (part->IsEmpty()) {
// Claiming ownership left this one empty.
delete part;
continue;
}
const TBOX& part_box = part->bounding_box();
int left_limit = LeftEdgeForBox(part_box, false, false);
int right_limit = RightEdgeForBox(part_box, false, false);
TBOX search_box = part_box;
int y = part->MidY();
int grid_x, grid_y;
GridCoords(part_box.left(), y, &grid_x, &grid_y);
// Set up a rectangle search x-bounded by the column and y by the part.
ColPartitionSet* columns = best_columns_[grid_y];
int first_col = -1;
int last_col = -1;
// Find which columns the partition spans.
part->ColumnRange(columns, &first_col, &last_col);
// Convert output column indices to physical column indices.
// Twiddle with first and last_col to get the desired effect with
// in-between columns:
// As returned by ColumnRange, the indices are even for in-betweens and
// odd for real columns (being 2n+1 the real column index).
// Subtract 1 from first col, so we can use left edge of first_col/2 if it
// is even, and the right edge of first_col/2 if it is odd.
// With last_col unchanged, we can use the right edge of last_col/2 if it
// is odd and the left edge of last_col/2 if it is even.
// with first_col, we have to special-case to pretend that the first
// in-between is actually the first column, and with last_col, we have to
// pretend that the last in-between is actually the last column.
if (first_col > 0)
--first_col;
ColPartition* first_column = columns->GetColumnByIndex(first_col / 2);
ColPartition* last_column = columns->GetColumnByIndex(last_col / 2);
if (last_column == NULL && last_col > first_col + 1)
last_column = columns->GetColumnByIndex(last_col / 2 - 1);
// Do not accept the case of both being in the first or last in-between.
if (last_col > 0 && first_column != NULL && last_column != NULL) {
search_box.set_left((first_col & 1) ? first_column->RightAtY(y)
: first_column->LeftAtY(y));
search_box.set_right((last_col & 1) ? last_column->RightAtY(y)
: last_column->LeftAtY(y));
// Expand the search vertically.
int height = search_box.height();
search_box.set_top(search_box.top() + height);
search_box.set_bottom(search_box.bottom() - height);
// Keep valid neighbours in a list.
ColPartition_CLIST neighbours;
// Now run the rect search.
GridSearch<ColPartition, ColPartition_CLIST, ColPartition_C_IT>
rsearch(&part_grid_);
rsearch.StartRectSearch(search_box);
ColPartition* neighbour;
while ((neighbour = rsearch.NextRectSearch()) != NULL) {
const TBOX& n_box = neighbour->bounding_box();
if (n_box.left() > right_limit || n_box.right() < left_limit)
continue; // Other side of a tab vector.
if (neighbour->blob_type() == BRT_RECTIMAGE) {
continue; // Rectangle images aren't allowed to acquire anything.
}
// We can't merge with a partition where it would go beyond the margin
// of the partition.
if ((part_box.left() < neighbour->left_margin() ||
part_box.right() > neighbour->right_margin()) &&
!n_box.contains(part_box)) {
continue; // This would create an overlap with another partition.
}
// Candidates must be within a reasonable vertical distance.
int v_dist = -part->VOverlap(*neighbour);
if (v_dist >= MAX(part_box.height(), n_box.height()) / 2)
continue;
// Unique elements as they arrive.
neighbours.add_sorted(SortByBoxLeft<ColPartition>, true, neighbour);
}
// The best neighbour to merge with is the one that causes least
// total pairwise overlap among all the candidates.
// If more than one offers the same total overlap, choose the one
// with the least total area.
ColPartition* best_neighbour = NULL;
ColPartition_C_IT n_it(&neighbours);
if (neighbours.singleton()) {
best_neighbour = n_it.data();
} else if (!neighbours.empty()) {
int best_overlap = MAX_INT32;
int best_area = 0;
for (n_it.mark_cycle_pt(); !n_it.cycled_list(); n_it.forward()) {
neighbour = n_it.data();
TBOX merged_box = neighbour->bounding_box();
merged_box += part_box;
int overlap = TotalPairwiseOverlap(neighbour, merged_box,
&neighbours);
if (best_neighbour == NULL || overlap < best_overlap) {
best_neighbour = neighbour;
best_overlap = overlap;
best_area = TotalArea(neighbour, merged_box, &neighbours);
} else if (overlap == best_overlap) {
int area = TotalArea(neighbour, merged_box, &neighbours);
if (area < best_area) {
best_area = area;
best_neighbour = neighbour;
}
}
}
}
if (best_neighbour != NULL) {
// It was close enough to an existing partition to merge it.
if (textord_debug_tabfind) {
tprintf("Merging unknown partition:\n");
part->Print();
best_neighbour->Print();
}
// Because the box is about to be resized, it must be removed and
// then re-inserted to prevent duplicates in the grid lists.
part_grid_.RemoveBBox(best_neighbour);
best_neighbour->Absorb(part, WidthCB());
// We modified the box of best_neighbour, so re-insert it into the grid.
part_grid_.InsertBBox(true, true, best_neighbour);
} else {
// It was inside a column, so just add it to the grid.
if (textord_debug_tabfind)
tprintf("Inserting unknown partition:\n");
part_grid_.InsertBBox(true, true, part);
}
} else {
if (textord_debug_tabfind) {
tprintf("Unknown partition at (%d,%d)->(%d,%d) not in any column\n",
part_box.left(), part_box.bottom(), part_box.right(),
part_box.top());
tprintf("first_col = %d->%p, last_col=%d->%p\n",
first_col, first_column, last_col, last_column);
}
noise_it.add_to_end(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();
int top = MAX(hline->startpt().y(), hline->endpt().y());
int bottom = MIN(hline->startpt().y(), hline->endpt().y());
if (top == bottom) {
if (bottom > 0)
--bottom;
else
++top;
}
ColPartition* part = new ColPartition(vertical_skew_,
hline->startpt().x(), bottom,
hline->endpt().x(), top);
part_grid_.InsertBBox(true, true, part);
}
}
// Improves the margins of the ColPartitions in the grid by calling
// FindPartitionMargins on each.
void ColumnFinder::GridFindMargins() {
// 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) {
// Set up a rectangle search x-bounded by the column and y by the part.
ColPartitionSet* columns = best_columns_[gsearch.GridY()];
FindPartitionMargins(columns, part);
}
}
// Improves the margins of the ColPartitions in the list by calling
// FindPartitionMargins on each.
void ColumnFinder::ListFindMargins(ColPartition_LIST* parts) {
ColPartition_IT part_it(parts);
for (part_it.mark_cycle_pt(); !part_it.cycled_list(); part_it.forward()) {
ColPartition* part = part_it.data();
TBOX part_box = part->bounding_box();
// Get the columns from the y grid coord.
int grid_x, grid_y;
GridCoords(part_box.left(), part_box.bottom(), &grid_x, &grid_y);
ColPartitionSet* columns = best_columns_[grid_y];
FindPartitionMargins(columns, part);
}
}
// Improves the margins of the ColPartition by searching for
// neighbours that vertically overlap significantly.
void ColumnFinder::FindPartitionMargins(ColPartitionSet* columns,
ColPartition* part) {
// Set up a rectangle search x-bounded by the column and y by the part.
ASSERT_HOST(columns != NULL);
TBOX box = part->bounding_box();
int y = part->MidY();
// Initial left margin is based on the column, if there is one.
ColPartition* column = columns->ColumnContaining(box.left(), y);
int left_margin = column != NULL ? column->LeftAtY(y) : bleft_.x();
left_margin -= kColumnWidthFactor;
// Search for ColPartitions that reduce the margin.
left_margin = FindMargin(box.left()+ box.height(), true, left_margin,
box.bottom(), box.top(), part);
part->set_left_margin(left_margin);
column = columns->ColumnContaining(box.right(), y);
int right_margin = column != NULL ? column->RightAtY(y) : tright_.x();
right_margin += kColumnWidthFactor;
// Search for ColPartitions that reduce the margin.
right_margin = FindMargin(box.right() - box.height(), false, right_margin,
box.bottom(), box.top(), part);
part->set_right_margin(right_margin);
}
// Starting at x, and going in the specified direction, upto x_limit, finds
// the margin for the given y range by searching sideways,
// and ignoring not_this.
int ColumnFinder::FindMargin(int x, bool right_to_left, int x_limit,
int y_bottom, int y_top,
const ColPartition* not_this) {
int height = y_top - y_bottom;
int target_overlap = static_cast<int>(height * kMarginOverlapFraction);
// Iterate the ColPartitions in the grid.
GridSearch<ColPartition, ColPartition_CLIST, ColPartition_C_IT>
side_search(&part_grid_);
side_search.StartSideSearch(x, y_bottom, y_top);
ColPartition* part;
while ((part = side_search.NextSideSearch(right_to_left)) != NULL) {
// Ignore itself.
if (part == not_this)
continue;
// Must overlap by enough.
TBOX box = part->bounding_box();
int y_overlap = MIN(y_top, box.top()) - MAX(y_bottom, box.bottom());
if (y_overlap < target_overlap)
continue;
// Must be going the right way.
int x_edge = right_to_left ? box.right() : box.left();
if ((x_edge < x) != right_to_left)
continue;
// If we have gone past x_limit, then x_limit will do.
if ((x_edge < x_limit) == right_to_left)
break;
// It reduces x limit, so save the new one.
x_limit = x_edge;
}
return x_limit;
}
// 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(best_columns_[gsearch.GridY()]);
}
}
//////// Functions that manipulate ColPartitions in the part_grid_ /////
//////// to find chains of partner partitions of the same type. ///////
// For every ColPartition in the grid, finds its upper and lower neighbours.
void ColumnFinder::FindPartitionPartners() {
GridSearch<ColPartition, ColPartition_CLIST, ColPartition_C_IT>
gsearch(&part_grid_);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
FindPartitionPartners(true, part);
FindPartitionPartners(false, part);
}
}
// Finds the best partner in the given direction for the given partition.
// Stores the result with AddPartner.
void ColumnFinder::FindPartitionPartners(bool upper, ColPartition* part) {
if (part->type() == PT_NOISE)
return; // Noise is not allowed to partner anything.
const TBOX& box = part->bounding_box();
int top = part->median_top();
int bottom = part->median_bottom();
int height = top - bottom;
int mid_y = (bottom + top) / 2;
GridSearch<ColPartition, ColPartition_CLIST, ColPartition_C_IT>
vsearch(&part_grid_);
// Search down for neighbour below
vsearch.StartVerticalSearch(box.left(), box.right(), part->MidY());
ColPartition* neighbour;
ColPartition* best_neighbour = NULL;
int best_dist = MAX_INT32;
while ((neighbour = vsearch.NextVerticalSearch(!upper)) != NULL) {
if (neighbour == part || neighbour->type() == PT_NOISE)
continue; // Noise is not allowed to partner anything.
int neighbour_bottom = neighbour->median_bottom();
int neighbour_top = neighbour->median_top();
int neighbour_y = (neighbour_bottom + neighbour_top) / 2;
if (upper != (neighbour_y > mid_y))
continue;
if (!part->HOverlaps(*neighbour) && !part->HCompatible(*neighbour))
continue;
if (!part->TypesMatch(*neighbour)) {
if (best_neighbour == NULL)
best_neighbour = neighbour;
continue;
}
int dist = upper ? neighbour_bottom - top : bottom - neighbour_top;
if (dist <= kMaxPartitionSpacing * height) {
if (dist < best_dist) {
best_dist = dist;
best_neighbour = neighbour;
}
} else {
break;
}
}
if (best_neighbour != NULL)
part->AddPartner(upper, best_neighbour);
}
// For every ColPartition with multiple partners in the grid, reduces the
// number of partners to 0 or 1.
void ColumnFinder::RefinePartitionPartners() {
// Refine in type order so that chasing multple partners can be done
// before eliminating type mis-matching partners.
for (int type = PT_UNKNOWN + 1; type <= PT_COUNT; type++) {
// 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) {
part->RefinePartners(static_cast<PolyBlockType>(type));
}
}
}
// 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) {
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->HCompatible(*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\n", gsearch.GridY());
}
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();
}
}
// Reskew the completed blocks to put them back to the original coords.
// (Blob outlines are not corrected for skew.)
// Rotate blobs and blocks individually so text line direction is
// horizontal. Record appropriate inverse transformations and required
// classifier transformation in the blocks.
void ColumnFinder::RotateAndReskewBlocks(TO_BLOCK_LIST* blocks) {
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;
block->set_index(block_index++);
BLOBNBOX_IT blob_it(&to_block->blobs);
// ColPartition::MakeBlock stored the inverse rotation that must be
// applied to small vertical blocks to go back to the original image
// coords at the end of recognition, but did not actually do any rotations,
// so now blocks must actually be rotated to make them horizontal by the
// inverse of that stored inverse rotation. This is of course a no-op
// for normal blocks.
FCOORD block_rotation = block->re_rotation();
block_rotation.set_y(-block_rotation.y());
block->poly_block()->rotate(block_rotation);
// The final stored inverse coordinate rotation (block->re_rotation_)
// is the sum of rerotate_ (for gross vertical pages) and the current
// block->re_rotation_ (for small vertical text regions).
// We will execute the inverse of that on all the blobs.
FCOORD blob_rotation = block->re_rotation();
blob_rotation.rotate(rerotate_);
block->set_re_rotation(blob_rotation);
blob_rotation.set_y(-blob_rotation.y());
// TODO(rays) determine classify rotation by orientation detection.
// In the mean time, it works for Chinese and English photo credits
// to set a classify rotation to the stored block rerotation only if
// the block rotation to do (before skew) is 0.
if (block_rotation.y() == 0.0f) {
block->set_classify_rotation(block->re_rotation());
}
// Blocks must also be rotated back by the skew angle.
block->rotate(reskew_);
// Save the skew in the block.
block->set_skew(reskew_);
// 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());
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
BLOBNBOX* blob = blob_it.data();
if (blob_rotation.y() != 0.0f) {
blob->cblob()->rotate(blob_rotation);
}
blob->compute_bounding_box();
widths.add(blob->bounding_box().width(), 1);
heights.add(blob->bounding_box().height(), 1);
}
block->set_median_size(static_cast<int>(widths.median() + 0.5),
static_cast<int>(heights.median() + 0.5));
if (textord_debug_tabfind > 1)
tprintf("Block median size = (%d, %d)\n",
block->median_size().x(), block->median_size().y());
}
}
// TransformToBlocks leaves all the small and noise blobs untouched in the
// source TO_BLOCK. MoveSmallBlobs moves them into the main blobs list of
// the block from the to_blocks list that contains them.
// TODO(rays) This is inefficient with a large number of blocks. A more
// efficient implementation is possible using a BBGrid.
void ColumnFinder::MoveSmallBlobs(BLOBNBOX_LIST* bblobs,
TO_BLOCK_LIST* to_blocks) {
for (BLOBNBOX_IT bb_it(bblobs); !bb_it.empty(); bb_it.forward()) {
BLOBNBOX* bblob = bb_it.extract();
const TBOX& bbox = bblob->bounding_box();
// Find the centre of the blob.
ICOORD centre = bbox.botleft();
centre += bbox.topright();
centre /= 2;
// Find the TO_BLOCK that contains the centre and put the blob in
// its main blobs list.
TO_BLOCK_IT to_it(to_blocks);
for (to_it.mark_cycle_pt(); !to_it.cycled_list(); to_it.forward()) {
TO_BLOCK* to_block = to_it.data();
BLOCK* block = to_block->block;
if (block->contains(centre)) {
BLOBNBOX_IT blob_it(&to_block->blobs);
blob_it.add_to_end(bblob);
bblob = NULL;
break;
}
}
if (bblob != NULL) {
delete bblob->cblob();
delete bblob;
}
}
}
} // namespace tesseract.
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