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tesseract/textord/colpartitiongrid.cpp
Ray Smith a1c22fb0d0 Fixed issue #557
2017-01-25 16:05:59 -08:00

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///////////////////////////////////////////////////////////////////////
// File: colpartitionrid.h
// Description: Class collecting code that acts on a BBGrid of ColPartitions.
// Author: Ray Smith
// Created: Mon Oct 05 08:42:01 PDT 2009
//
// (C) Copyright 2009, 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 HAVE_CONFIG_H
#include "config_auto.h"
#endif
#include "colpartitiongrid.h"
#include "colpartitionset.h"
#include "imagefind.h"
namespace tesseract {
BOOL_VAR(textord_tabfind_show_color_fit, false, "Show stroke widths");
// Max pad factor used to search the neighbourhood of a partition to smooth
// partition types.
const int kMaxPadFactor = 6;
// Max multiple of size (min(height, width)) for the distance of the nearest
// neighbour for the change of type to be used.
const int kMaxNeighbourDistFactor = 4;
// Maximum number of lines in a credible figure caption.
const int kMaxCaptionLines = 7;
// Min ratio between biggest and smallest gap to bound a caption.
const double kMinCaptionGapRatio = 2.0;
// Min ratio between biggest gap and mean line height to bound a caption.
const double kMinCaptionGapHeightRatio = 0.5;
// Min fraction of ColPartition height to be overlapping for margin purposes.
const double kMarginOverlapFraction = 0.25;
// Size ratio required to consider an unmerged overlapping partition to be big.
const double kBigPartSizeRatio = 1.75;
// Fraction of gridsize to allow arbitrary overlap between partitions.
const double kTinyEnoughTextlineOverlapFraction = 0.25;
// Max vertical distance of neighbouring ColPartition as a multiple of
// partition height for it to be a partner.
// TODO(rays) fix the problem that causes a larger number to not work well.
// The value needs to be larger as sparse text blocks in a page that gets
// marked as single column will not find adjacent lines as partners, and
// will merge horizontally distant, but aligned lines. See rep.4B3 p5.
// The value needs to be small because double-spaced legal docs written
// in a single column, but justified courier have widely spaced lines
// that need to get merged before they partner-up with the lines above
// and below. See legal.3B5 p13/17. Neither of these should depend on
// the value of kMaxPartitionSpacing to be successful, and ColPartition
// merging needs attention to fix this problem.
const double kMaxPartitionSpacing = 1.75;
// Margin by which text has to beat image or vice-versa to make a firm
// decision in GridSmoothNeighbour.
const int kSmoothDecisionMargin = 4;
ColPartitionGrid::ColPartitionGrid() {
}
ColPartitionGrid::ColPartitionGrid(int gridsize,
const ICOORD& bleft, const ICOORD& tright)
: BBGrid<ColPartition, ColPartition_CLIST, ColPartition_C_IT>(gridsize,
bleft, tright) {
}
ColPartitionGrid::~ColPartitionGrid() {
}
// Handles a click event in a display window.
void ColPartitionGrid::HandleClick(int x, int y) {
BBGrid<ColPartition,
ColPartition_CLIST, ColPartition_C_IT>::HandleClick(x, y);
// Run a radial search for partitions that overlap.
ColPartitionGridSearch radsearch(this);
radsearch.SetUniqueMode(true);
radsearch.StartRadSearch(x, y, 1);
ColPartition* neighbour;
FCOORD click(x, y);
while ((neighbour = radsearch.NextRadSearch()) != NULL) {
const TBOX& nbox = neighbour->bounding_box();
if (nbox.contains(click)) {
tprintf("Block box:");
neighbour->bounding_box().print();
neighbour->Print();
}
}
}
// Merges ColPartitions in the grid that look like they belong in the same
// textline.
// For all partitions in the grid, calls the box_cb permanent callback
// to compute the search box, searches the box, and if a candidate is found,
// calls the confirm_cb to check any more rules. If the confirm_cb returns
// true, then the partitions are merged.
// Both callbacks are deleted before returning.
void ColPartitionGrid::Merges(
TessResultCallback2<bool, ColPartition*, TBOX*>* box_cb,
TessResultCallback2<bool, const ColPartition*,
const ColPartition*>* confirm_cb) {
// Iterate the ColPartitions in the grid.
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
if (MergePart(box_cb, confirm_cb, part))
gsearch.RepositionIterator();
}
delete box_cb;
delete confirm_cb;
}
// For the given partition, calls the box_cb permanent callback
// to compute the search box, searches the box, and if a candidate is found,
// calls the confirm_cb to check any more rules. If the confirm_cb returns
// true, then the partitions are merged.
// Returns true if the partition is consumed by one or more merges.
bool ColPartitionGrid::MergePart(
TessResultCallback2<bool, ColPartition*, TBOX*>* box_cb,
TessResultCallback2<bool, const ColPartition*,
const ColPartition*>* confirm_cb,
ColPartition* part) {
if (part->IsUnMergeableType())
return false;
bool any_done = false;
// Repeatedly merge part while we find a best merge candidate that works.
bool merge_done = false;
do {
merge_done = false;
TBOX box = part->bounding_box();
bool debug = AlignedBlob::WithinTestRegion(2, box.left(), box.bottom());
if (debug) {
tprintf("Merge candidate:");
box.print();
}
// Set up a rectangle search bounded by the part.
if (!box_cb->Run(part, &box))
continue;
// Create a list of merge candidates.
ColPartition_CLIST merge_candidates;
FindMergeCandidates(part, box, debug, &merge_candidates);
// Find the best merge candidate based on minimal overlap increase.
int overlap_increase;
ColPartition* neighbour = BestMergeCandidate(part, &merge_candidates, debug,
confirm_cb,
&overlap_increase);
if (neighbour != NULL && overlap_increase <= 0) {
if (debug) {
tprintf("Merging:hoverlap=%d, voverlap=%d, OLI=%d\n",
part->HCoreOverlap(*neighbour), part->VCoreOverlap(*neighbour),
overlap_increase);
}
// Looks like a good candidate so merge it.
RemoveBBox(neighbour);
// We will modify the box of part, so remove it from the grid, merge
// it and then re-insert it into the grid.
RemoveBBox(part);
part->Absorb(neighbour, NULL);
InsertBBox(true, true, part);
merge_done = true;
any_done = true;
} else if (neighbour != NULL) {
if (debug) {
tprintf("Overlapped when merged with increase %d: ", overlap_increase);
neighbour->bounding_box().print();
}
} else if (debug) {
tprintf("No candidate neighbour returned\n");
}
} while (merge_done);
return any_done;
}
// Returns true if the given part and merge candidate might believably
// be part of a single text line according to the default rules.
// In general we only want to merge partitions that look like they
// are on the same text line, ie their median limits overlap, but we have
// to make exceptions for diacritics and stray punctuation.
static bool OKMergeCandidate(const ColPartition* part,
const ColPartition* candidate,
bool debug) {
const TBOX& part_box = part->bounding_box();
if (candidate == part)
return false; // Ignore itself.
if (!part->TypesMatch(*candidate) || candidate->IsUnMergeableType())
return false; // Don't mix inappropriate types.
const TBOX& c_box = candidate->bounding_box();
if (debug) {
tprintf("Examining merge candidate:");
c_box.print();
}
// Candidates must be within a reasonable distance.
if (candidate->IsVerticalType() || part->IsVerticalType()) {
int h_dist = -part->HCoreOverlap(*candidate);
if (h_dist >= MAX(part_box.width(), c_box.width()) / 2) {
if (debug)
tprintf("Too far away: h_dist = %d\n", h_dist);
return false;
}
} else {
// Coarse filter by vertical distance between partitions.
int v_dist = -part->VCoreOverlap(*candidate);
if (v_dist >= MAX(part_box.height(), c_box.height()) / 2) {
if (debug)
tprintf("Too far away: v_dist = %d\n", v_dist);
return false;
}
// Candidates must either overlap in median y,
// or part or candidate must be an acceptable diacritic.
if (!part->VSignificantCoreOverlap(*candidate) &&
!part->OKDiacriticMerge(*candidate, debug) &&
!candidate->OKDiacriticMerge(*part, debug)) {
if (debug)
tprintf("Candidate fails overlap and diacritic tests!\n");
return false;
}
}
return true;
}
// Helper function to compute the increase in overlap of the parts list of
// Colpartitions with the combination of merge1 and merge2, compared to
// the overlap with them uncombined.
// An overlap is not counted if passes the OKMergeOverlap test with ok_overlap
// as the pixel overlap limit. merge1 and merge2 must both be non-NULL.
static int IncreaseInOverlap(const ColPartition* merge1,
const ColPartition* merge2,
int ok_overlap,
ColPartition_CLIST* parts) {
ASSERT_HOST(merge1 != NULL && merge2 != NULL);
int total_area = 0;
ColPartition_C_IT it(parts);
TBOX merged_box(merge1->bounding_box());
merged_box += merge2->bounding_box();
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* part = it.data();
if (part == merge1 || part == merge2)
continue;
TBOX part_box = part->bounding_box();
// Compute the overlap of the merged box with part.
int overlap_area = part_box.intersection(merged_box).area();
if (overlap_area > 0 && !part->OKMergeOverlap(*merge1, *merge2,
ok_overlap, false)) {
total_area += overlap_area;
// Subtract the overlap of merge1 and merge2 individually.
overlap_area = part_box.intersection(merge1->bounding_box()).area();
if (overlap_area > 0)
total_area -= overlap_area;
TBOX intersection_box = part_box.intersection(merge2->bounding_box());
overlap_area = intersection_box.area();
if (overlap_area > 0) {
total_area -= overlap_area;
// Add back the 3-way area.
intersection_box &= merge1->bounding_box(); // In-place intersection.
overlap_area = intersection_box.area();
if (overlap_area > 0)
total_area += overlap_area;
}
}
}
return total_area;
}
// Helper function to test that each partition in candidates is either a
// good diacritic merge with part or an OK merge candidate with all others
// in the candidates list.
// ASCII Art Scenario:
// We sometimes get text such as "join-this" where the - is actually a long
// dash culled from a standard set of extra characters that don't match the
// font of the text. This makes its strokewidth not match and forms a broken
// set of 3 partitions for "join", "-" and "this" and the dash may slightly
// overlap BOTH words.
// ------- -------
// | ==== |
// ------- -------
// The standard merge rule: "you can merge 2 partitions as long as there is
// no increase in overlap elsewhere" fails miserably here. Merge any pair
// of partitions and the combined box overlaps more with the third than
// before. To allow the merge, we need to consider whether it is safe to
// merge everything, without merging separate text lines. For that we need
// everything to be an OKMergeCandidate (which is supposed to prevent
// separate text lines merging), but this is hard for diacritics to satisfy,
// so an alternative to being OKMergeCandidate with everything is to be an
// OKDiacriticMerge with part as the base character.
static bool TestCompatibleCandidates(const ColPartition& part, bool debug,
ColPartition_CLIST* candidates) {
ColPartition_C_IT it(candidates);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* candidate = it.data();
if (!candidate->OKDiacriticMerge(part, false)) {
ColPartition_C_IT it2(it);
for (it2.mark_cycle_pt(); !it2.cycled_list(); it2.forward()) {
ColPartition* candidate2 = it2.data();
if (candidate2 != candidate &&
!OKMergeCandidate(candidate, candidate2, false)) {
if (debug) {
tprintf("NC overlap failed:Candidate:");
candidate2->bounding_box().print();
tprintf("fails to be a good merge with:");
candidate->bounding_box().print();
}
return false;
}
}
}
}
return true;
}
// Computes and returns the total overlap of all partitions in the grid.
// If overlap_grid is non-null, it is filled with a grid that holds empty
// partitions representing the union of all overlapped partitions.
int ColPartitionGrid::ComputeTotalOverlap(ColPartitionGrid** overlap_grid) {
int total_overlap = 0;
// Iterate the ColPartitions in the grid.
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
ColPartition_CLIST neighbors;
const TBOX& part_box = part->bounding_box();
FindOverlappingPartitions(part_box, part, &neighbors);
ColPartition_C_IT n_it(&neighbors);
bool any_part_overlap = false;
for (n_it.mark_cycle_pt(); !n_it.cycled_list(); n_it.forward()) {
const TBOX& n_box = n_it.data()->bounding_box();
int overlap = n_box.intersection(part_box).area();
if (overlap > 0 && overlap_grid != NULL) {
if (*overlap_grid == NULL) {
*overlap_grid = new ColPartitionGrid(gridsize(), bleft(), tright());
}
(*overlap_grid)->InsertBBox(true, true, n_it.data()->ShallowCopy());
if (!any_part_overlap) {
(*overlap_grid)->InsertBBox(true, true, part->ShallowCopy());
}
}
any_part_overlap = true;
total_overlap += overlap;
}
}
return total_overlap;
}
// Finds all the ColPartitions in the grid that overlap with the given
// box and returns them SortByBoxLeft(ed) and uniqued in the given list.
// Any partition equal to not_this (may be NULL) is excluded.
void ColPartitionGrid::FindOverlappingPartitions(const TBOX& box,
const ColPartition* not_this,
ColPartition_CLIST* parts) {
ColPartitionGridSearch rsearch(this);
rsearch.StartRectSearch(box);
ColPartition* part;
while ((part = rsearch.NextRectSearch()) != NULL) {
if (part != not_this)
parts->add_sorted(SortByBoxLeft<ColPartition>, true, part);
}
}
// Finds and returns the best candidate ColPartition to merge with part,
// selected from the candidates list, based on the minimum increase in
// pairwise overlap among all the partitions overlapped by the combined box.
// If overlap_increase is not NULL then it returns the increase in overlap
// that would result from the merge.
// confirm_cb is a permanent callback that (if non-null) will be used to
// confirm the validity of a proposed merge candidate before selecting it.
//
// ======HOW MERGING WORKS======
// The problem:
// We want to merge all the parts of a textline together, but avoid merging
// separate textlines. Diacritics, i dots, punctuation, and broken characters
// are examples of small bits that need merging with the main textline.
// Drop-caps and descenders in one line that touch ascenders in the one below
// are examples of cases where we don't want to merge.
//
// The solution:
// Merges that increase overlap among other partitions are generally bad.
// Those that don't increase overlap (much) and minimize the total area
// seem to be good.
//
// Ascii art example:
// The text:
// groggy descenders
// minimum ascenders
// The boxes: The === represents a small box near or overlapping the lower box.
// -----------------
// | |
// -----------------
// -===-------------
// | |
// -----------------
// In considering what to do with the small === box, we find the 2 larger
// boxes as neighbours and possible merge candidates, but merging with the
// upper box increases overlap with the lower box, whereas merging with the
// lower box does not increase overlap.
// If the small === box didn't overlap either to start with, total area
// would be minimized by merging with the nearer (lower) box.
//
// This is a simple example. In reality, we have to allow some increase
// in overlap, or tightly spaced text would end up in bits.
ColPartition* ColPartitionGrid::BestMergeCandidate(
const ColPartition* part, ColPartition_CLIST* candidates, bool debug,
TessResultCallback2<bool, const ColPartition*, const ColPartition*>* confirm_cb,
int* overlap_increase) {
if (overlap_increase != NULL)
*overlap_increase = 0;
if (candidates->empty())
return NULL;
int ok_overlap =
static_cast<int>(kTinyEnoughTextlineOverlapFraction * gridsize() + 0.5);
// The best neighbour to merge with is the one that causes least
// total pairwise overlap among all the neighbours.
// If more than one offers the same total overlap, choose the one
// with the least total area.
const TBOX& part_box = part->bounding_box();
ColPartition_C_IT it(candidates);
ColPartition* best_candidate = NULL;
// Find the total combined box of all candidates and the original.
TBOX full_box(part_box);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* candidate = it.data();
full_box += candidate->bounding_box();
}
// Keep valid neighbours in a list.
ColPartition_CLIST neighbours;
// Now run a rect search of the merged box for overlapping neighbours, as
// we need anything that might be overlapped by the merged box.
FindOverlappingPartitions(full_box, part, &neighbours);
if (debug) {
tprintf("Finding best merge candidate from %d, %d neighbours for box:",
candidates->length(), neighbours.length());
part_box.print();
}
// If the best increase in overlap is positive, then we also check the
// worst non-candidate overlap. This catches the case of multiple good
// candidates that overlap each other when merged. If the worst
// non-candidate overlap is better than the best overlap, then return
// the worst non-candidate overlap instead.
ColPartition_CLIST non_candidate_neighbours;
non_candidate_neighbours.set_subtract(SortByBoxLeft<ColPartition>, true,
&neighbours, candidates);
int worst_nc_increase = 0;
int best_increase = MAX_INT32;
int best_area = 0;
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ColPartition* candidate = it.data();
if (confirm_cb != NULL && !confirm_cb->Run(part, candidate)) {
if (debug) {
tprintf("Candidate not confirmed:");
candidate->bounding_box().print();
}
continue;
}
int increase = IncreaseInOverlap(part, candidate, ok_overlap, &neighbours);
const TBOX& cand_box = candidate->bounding_box();
if (best_candidate == NULL || increase < best_increase) {
best_candidate = candidate;
best_increase = increase;
best_area = cand_box.bounding_union(part_box).area() - cand_box.area();
if (debug) {
tprintf("New best merge candidate has increase %d, area %d, over box:",
increase, best_area);
full_box.print();
candidate->Print();
}
} else if (increase == best_increase) {
int area = cand_box.bounding_union(part_box).area() - cand_box.area();
if (area < best_area) {
best_area = area;
best_candidate = candidate;
}
}
increase = IncreaseInOverlap(part, candidate, ok_overlap,
&non_candidate_neighbours);
if (increase > worst_nc_increase)
worst_nc_increase = increase;
}
if (best_increase > 0) {
// If the worst non-candidate increase is less than the best increase
// including the candidates, then all the candidates can merge together
// and the increase in outside overlap would be less, so use that result,
// but only if each candidate is either a good diacritic merge with part,
// or an ok merge candidate with all the others.
// See TestCompatibleCandidates for more explanation and a picture.
if (worst_nc_increase < best_increase &&
TestCompatibleCandidates(*part, debug, candidates)) {
best_increase = worst_nc_increase;
}
}
if (overlap_increase != NULL)
*overlap_increase = best_increase;
return best_candidate;
}
// Helper to remove the given box from the given partition, put it in its
// own partition, and add to the partition list.
static void RemoveBadBox(BLOBNBOX* box, ColPartition* part,
ColPartition_LIST* part_list) {
part->RemoveBox(box);
ColPartition::MakeBigPartition(box, part_list);
}
// Split partitions where it reduces overlap between their bounding boxes.
// ColPartitions are after all supposed to be a partitioning of the blobs
// AND of the space on the page!
// Blobs that cause overlaps get removed, put in individual partitions
// and added to the big_parts list. They are most likely characters on
// 2 textlines that touch, or something big like a dropcap.
void ColPartitionGrid::SplitOverlappingPartitions(
ColPartition_LIST* big_parts) {
int ok_overlap =
static_cast<int>(kTinyEnoughTextlineOverlapFraction * gridsize() + 0.5);
// Iterate the ColPartitions in the grid.
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
// Set up a rectangle search bounded by the part.
const TBOX& box = part->bounding_box();
ColPartitionGridSearch rsearch(this);
rsearch.SetUniqueMode(true);
rsearch.StartRectSearch(box);
int unresolved_overlaps = 0;
ColPartition* neighbour;
while ((neighbour = rsearch.NextRectSearch()) != NULL) {
if (neighbour == part)
continue;
const TBOX& neighbour_box = neighbour->bounding_box();
if (neighbour->OKMergeOverlap(*part, *part, ok_overlap, false) &&
part->OKMergeOverlap(*neighbour, *neighbour, ok_overlap, false))
continue; // The overlap is OK both ways.
// If removal of the biggest box from either partition eliminates the
// overlap, and it is much bigger than the box left behind, then
// it is either a drop-cap, an inter-line join, or some junk that
// we don't want anyway, so put it in the big_parts list.
if (!part->IsSingleton()) {
BLOBNBOX* excluded = part->BiggestBox();
TBOX shrunken = part->BoundsWithoutBox(excluded);
if (!shrunken.overlap(neighbour_box) &&
excluded->bounding_box().height() >
kBigPartSizeRatio * shrunken.height()) {
// Removing the biggest box fixes the overlap, so do it!
gsearch.RemoveBBox();
RemoveBadBox(excluded, part, big_parts);
InsertBBox(true, true, part);
gsearch.RepositionIterator();
break;
}
} else if (box.contains(neighbour_box)) {
++unresolved_overlaps;
continue; // No amount of splitting will fix it.
}
if (!neighbour->IsSingleton()) {
BLOBNBOX* excluded = neighbour->BiggestBox();
TBOX shrunken = neighbour->BoundsWithoutBox(excluded);
if (!shrunken.overlap(box) &&
excluded->bounding_box().height() >
kBigPartSizeRatio * shrunken.height()) {
// Removing the biggest box fixes the overlap, so do it!
rsearch.RemoveBBox();
RemoveBadBox(excluded, neighbour, big_parts);
InsertBBox(true, true, neighbour);
gsearch.RepositionIterator();
break;
}
}
int part_overlap_count = part->CountOverlappingBoxes(neighbour_box);
int neighbour_overlap_count = neighbour->CountOverlappingBoxes(box);
ColPartition* right_part = NULL;
if (neighbour_overlap_count <= part_overlap_count ||
part->IsSingleton()) {
// Try to split the neighbour to reduce overlap.
BLOBNBOX* split_blob = neighbour->OverlapSplitBlob(box);
if (split_blob != NULL) {
rsearch.RemoveBBox();
right_part = neighbour->SplitAtBlob(split_blob);
InsertBBox(true, true, neighbour);
ASSERT_HOST(right_part != NULL);
}
} else {
// Try to split part to reduce overlap.
BLOBNBOX* split_blob = part->OverlapSplitBlob(neighbour_box);
if (split_blob != NULL) {
gsearch.RemoveBBox();
right_part = part->SplitAtBlob(split_blob);
InsertBBox(true, true, part);
ASSERT_HOST(right_part != NULL);
}
}
if (right_part != NULL) {
InsertBBox(true, true, right_part);
gsearch.RepositionIterator();
rsearch.RepositionIterator();
break;
}
}
if (unresolved_overlaps > 2 && part->IsSingleton()) {
// This part is no good so just add to big_parts.
RemoveBBox(part);
ColPartition_IT big_it(big_parts);
part->set_block_owned(true);
big_it.add_to_end(part);
gsearch.RepositionIterator();
}
}
}
// Filters partitions of source_type by looking at local neighbours.
// Where a majority of neighbours have a text type, the partitions are
// changed to text, where the neighbours have image type, they are changed
// to image, and partitions that have no definite neighbourhood type are
// left unchanged.
// im_box and rerotation are used to map blob coordinates onto the
// nontext_map, which is used to prevent the spread of text neighbourhoods
// into images.
// Returns true if anything was changed.
bool ColPartitionGrid::GridSmoothNeighbours(BlobTextFlowType source_type,
Pix* nontext_map,
const TBOX& im_box,
const FCOORD& rotation) {
// Iterate the ColPartitions in the grid.
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
bool any_changed = false;
while ((part = gsearch.NextFullSearch()) != NULL) {
if (part->flow() != source_type || BLOBNBOX::IsLineType(part->blob_type()))
continue;
const TBOX& box = part->bounding_box();
bool debug = AlignedBlob::WithinTestRegion(2, box.left(), box.bottom());
if (SmoothRegionType(nontext_map, im_box, rotation, debug, part))
any_changed = true;
}
return any_changed;
}
// Reflects the grid and its colpartitions in the y-axis, assuming that
// all blob boxes have already been done.
void ColPartitionGrid::ReflectInYAxis() {
ColPartition_LIST parts;
ColPartition_IT part_it(&parts);
// Iterate the ColPartitions in the grid to extract them.
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
part_it.add_after_then_move(part);
}
ICOORD bot_left(-tright().x(), bleft().y());
ICOORD top_right(-bleft().x(), tright().y());
// Reinitializing the grid with reflected coords also clears all the
// pointers, so parts will now own the ColPartitions. (Briefly).
Init(gridsize(), bot_left, top_right);
for (part_it.move_to_first(); !part_it.empty(); part_it.forward()) {
part = part_it.extract();
part->ReflectInYAxis();
InsertBBox(true, true, part);
}
}
// Transforms the grid of partitions to the output blocks, putting each
// partition into a separate block. We don't really care about the order,
// as we just want to get as much text as possible without trying to organize
// it into proper blocks or columns.
// TODO(rays) some kind of sort function would be useful and probably better
// than the default here, which is to sort by order of the grid search.
void ColPartitionGrid::ExtractPartitionsAsBlocks(BLOCK_LIST* blocks,
TO_BLOCK_LIST* to_blocks) {
TO_BLOCK_IT to_block_it(to_blocks);
BLOCK_IT block_it(blocks);
// All partitions will be put on this list and deleted on return.
ColPartition_LIST parts;
ColPartition_IT part_it(&parts);
// Iterate the ColPartitions in the grid to extract them.
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
part_it.add_after_then_move(part);
// The partition has to be at least vaguely like text.
BlobRegionType blob_type = part->blob_type();
if (BLOBNBOX::IsTextType(blob_type) ||
(blob_type == BRT_UNKNOWN && part->boxes_count() > 1)) {
PolyBlockType type = blob_type == BRT_VERT_TEXT ? PT_VERTICAL_TEXT
: PT_FLOWING_TEXT;
// Get metrics from the row that will be used for the block.
TBOX box = part->bounding_box();
int median_width = part->median_width();
int median_height = part->median_size();
// Turn the partition into a TO_ROW.
TO_ROW* row = part->MakeToRow();
if (row == NULL) {
// This partition is dead.
part->DeleteBoxes();
continue;
}
BLOCK* block = new BLOCK("", true, 0, 0, box.left(), box.bottom(),
box.right(), box.top());
block->set_poly_block(new POLY_BLOCK(box, type));
TO_BLOCK* to_block = new TO_BLOCK(block);
TO_ROW_IT row_it(to_block->get_rows());
row_it.add_after_then_move(row);
// We haven't differentially rotated vertical and horizontal text at
// this point, so use width or height as appropriate.
if (blob_type == BRT_VERT_TEXT) {
to_block->line_size = static_cast<float>(median_width);
to_block->line_spacing = static_cast<float>(box.width());
to_block->max_blob_size = static_cast<float>(box.width() + 1);
} else {
to_block->line_size = static_cast<float>(median_height);
to_block->line_spacing = static_cast<float>(box.height());
to_block->max_blob_size = static_cast<float>(box.height() + 1);
}
block_it.add_to_end(block);
to_block_it.add_to_end(to_block);
} else {
// This partition is dead.
part->DeleteBoxes();
}
}
Clear();
// Now it is safe to delete the ColPartitions as parts goes out of scope.
}
// Rotates the grid and its colpartitions by the given angle, assuming that
// all blob boxes have already been done.
void ColPartitionGrid::Deskew(const FCOORD& deskew) {
ColPartition_LIST parts;
ColPartition_IT part_it(&parts);
// Iterate the ColPartitions in the grid to extract them.
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
part_it.add_after_then_move(part);
}
// Rebuild the grid to the new size.
TBOX grid_box(bleft_, tright_);
grid_box.rotate_large(deskew);
Init(gridsize(), grid_box.botleft(), grid_box.topright());
// Reinitializing the grid with rotated coords also clears all the
// pointers, so parts will now own the ColPartitions. (Briefly).
for (part_it.move_to_first(); !part_it.empty(); part_it.forward()) {
part = part_it.extract();
part->ComputeLimits();
InsertBBox(true, true, part);
}
}
// Sets the left and right tabs of the partitions in the grid.
void ColPartitionGrid::SetTabStops(TabFind* tabgrid) {
// Iterate the ColPartitions in the grid.
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
const TBOX& part_box = part->bounding_box();
TabVector* left_line = tabgrid->LeftTabForBox(part_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 = tabgrid->LeftTabForBox(part_box, false, false);
if (left_line != NULL && left_line->IsLeftTab())
part->SetLeftTab(left_line);
TabVector* right_line = tabgrid->RightTabForBox(part_box, true, false);
if (right_line != NULL && !right_line->IsRightTab())
right_line = tabgrid->RightTabForBox(part_box, false, false);
if (right_line != NULL && right_line->IsRightTab())
part->SetRightTab(right_line);
part->SetColumnGoodness(tabgrid->WidthCB());
}
}
// Makes the ColPartSets and puts them in the PartSetVector ready
// for finding column bounds. Returns false if no partitions were found.
bool ColPartitionGrid::MakeColPartSets(PartSetVector* part_sets) {
ColPartition_LIST* part_lists = new ColPartition_LIST[gridheight()];
part_sets->reserve(gridheight());
// Iterate the ColPartitions in the grid to get parts onto lists for the
// y bottom of each.
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
bool any_parts_found = false;
while ((part = gsearch.NextFullSearch()) != NULL) {
BlobRegionType blob_type = part->blob_type();
if (blob_type != BRT_NOISE &&
(blob_type != BRT_UNKNOWN || !part->boxes()->singleton())) {
int grid_x, grid_y;
const TBOX& part_box = part->bounding_box();
GridCoords(part_box.left(), part_box.bottom(), &grid_x, &grid_y);
ColPartition_IT part_it(&part_lists[grid_y]);
part_it.add_to_end(part);
any_parts_found = true;
}
}
if (any_parts_found) {
for (int grid_y = 0; grid_y < gridheight(); ++grid_y) {
ColPartitionSet* line_set = NULL;
if (!part_lists[grid_y].empty()) {
line_set = new ColPartitionSet(&part_lists[grid_y]);
}
part_sets->push_back(line_set);
}
}
delete [] part_lists;
return any_parts_found;
}
// Makes a single ColPartitionSet consisting of a single ColPartition that
// represents the total horizontal extent of the significant content on the
// page. Used for the single column setting in place of automatic detection.
// Returns NULL if the page is empty of significant content.
ColPartitionSet* ColPartitionGrid::MakeSingleColumnSet(WidthCallback* cb) {
ColPartition* single_column_part = NULL;
// Iterate the ColPartitions in the grid to get parts onto lists for the
// y bottom of each.
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
BlobRegionType blob_type = part->blob_type();
if (blob_type != BRT_NOISE &&
(blob_type != BRT_UNKNOWN || !part->boxes()->singleton())) {
// Consider for single column.
BlobTextFlowType flow = part->flow();
if ((blob_type == BRT_TEXT &&
(flow == BTFT_STRONG_CHAIN || flow == BTFT_CHAIN ||
flow == BTFT_LEADER || flow == BTFT_TEXT_ON_IMAGE)) ||
blob_type == BRT_RECTIMAGE || blob_type == BRT_POLYIMAGE) {
if (single_column_part == NULL) {
single_column_part = part->ShallowCopy();
single_column_part->set_blob_type(BRT_TEXT);
// Copy the tabs from itself to properly setup the margins.
single_column_part->CopyLeftTab(*single_column_part, false);
single_column_part->CopyRightTab(*single_column_part, false);
} else {
if (part->left_key() < single_column_part->left_key())
single_column_part->CopyLeftTab(*part, false);
if (part->right_key() > single_column_part->right_key())
single_column_part->CopyRightTab(*part, false);
}
}
}
}
if (single_column_part != NULL) {
// Make a ColPartitionSet out of the single_column_part as a candidate
// for the single column case.
single_column_part->SetColumnGoodness(cb);
return new ColPartitionSet(single_column_part);
}
return NULL;
}
// Mark the BLOBNBOXes in each partition as being owned by that partition.
void ColPartitionGrid::ClaimBoxes() {
// Iterate the ColPartitions in the grid.
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
part->ClaimBoxes();
}
}
// Retypes all the blobs referenced by the partitions in the grid.
// Image blobs are found and returned in the im_blobs list, as they are not
// owned by the block.
void ColPartitionGrid::ReTypeBlobs(BLOBNBOX_LIST* im_blobs) {
BLOBNBOX_IT im_blob_it(im_blobs);
ColPartition_LIST dead_parts;
ColPartition_IT dead_part_it(&dead_parts);
// Iterate the ColPartitions in the grid.
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
BlobRegionType blob_type = part->blob_type();
BlobTextFlowType flow = part->flow();
bool any_blobs_moved = false;
if (blob_type == BRT_POLYIMAGE || blob_type == BRT_RECTIMAGE) {
BLOBNBOX_C_IT blob_it(part->boxes());
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
BLOBNBOX* blob = blob_it.data();
im_blob_it.add_after_then_move(blob);
}
} else if (blob_type != BRT_NOISE) {
// Make sure the blobs are marked with the correct type and flow.
BLOBNBOX_C_IT blob_it(part->boxes());
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
BLOBNBOX* blob = blob_it.data();
if (blob->region_type() == BRT_NOISE) {
// TODO(rays) Deprecated. Change this section to an assert to verify
// and then delete.
ASSERT_HOST(blob->cblob()->area() != 0);
blob->set_owner(NULL);
blob_it.extract();
any_blobs_moved = true;
} else {
blob->set_region_type(blob_type);
if (blob->flow() != BTFT_LEADER)
blob->set_flow(flow);
}
}
}
if (blob_type == BRT_NOISE || part->boxes()->empty()) {
BLOBNBOX_C_IT blob_it(part->boxes());
part->DisownBoxes();
dead_part_it.add_to_end(part);
gsearch.RemoveBBox();
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
BLOBNBOX* blob = blob_it.data();
if (blob->cblob()->area() == 0) {
// Any blob with zero area is a fake image blob and should be deleted.
delete blob->cblob();
delete blob;
}
}
} else if (any_blobs_moved) {
gsearch.RemoveBBox();
part->ComputeLimits();
InsertBBox(true, true, part);
gsearch.RepositionIterator();
}
}
}
// The boxes within the partitions have changed (by deskew) so recompute
// the bounds of all the partitions and reinsert them into the grid.
void ColPartitionGrid::RecomputeBounds(int gridsize,
const ICOORD& bleft,
const ICOORD& tright,
const ICOORD& vertical) {
ColPartition_LIST saved_parts;
ColPartition_IT part_it(&saved_parts);
// Iterate the ColPartitions in the grid to get parts onto a list.
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
part_it.add_to_end(part);
}
// Reinitialize grid to the new size.
Init(gridsize, bleft, tright);
// Recompute the bounds of the parts and put them back in the new grid.
for (part_it.move_to_first(); !part_it.empty(); part_it.forward()) {
part = part_it.extract();
part->set_vertical(vertical);
part->ComputeLimits();
InsertBBox(true, true, part);
}
}
// Improves the margins of the ColPartitions in the grid by calling
// FindPartitionMargins on each.
// best_columns, which may be NULL, is an array of pointers indicating the
// column set at each y-coordinate in the grid.
// best_columns is usually the best_columns_ member of ColumnFinder.
void ColPartitionGrid::GridFindMargins(ColPartitionSet** best_columns) {
// Iterate the ColPartitions in the grid.
ColPartitionGridSearch gsearch(this);
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 != NULL
? best_columns[gsearch.GridY()]
: NULL;
FindPartitionMargins(columns, part);
const TBOX& box = part->bounding_box();
if (AlignedBlob::WithinTestRegion(2, box.left(), box.bottom())) {
tprintf("Computed margins for part:");
part->Print();
}
}
}
// Improves the margins of the ColPartitions in the list by calling
// FindPartitionMargins on each.
// best_columns, which may be NULL, is an array of pointers indicating the
// column set at each y-coordinate in the grid.
// best_columns is usually the best_columns_ member of ColumnFinder.
void ColPartitionGrid::ListFindMargins(ColPartitionSet** best_columns,
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();
ColPartitionSet* columns = NULL;
if (best_columns != NULL) {
const 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);
columns = best_columns[grid_y];
}
FindPartitionMargins(columns, part);
}
}
// Deletes all the partitions in the grid after disowning all the blobs.
void ColPartitionGrid::DeleteParts() {
ColPartition_LIST dead_parts;
ColPartition_IT dead_it(&dead_parts);
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
part->DisownBoxes();
dead_it.add_to_end(part); // Parts will be deleted on return.
}
Clear();
}
// Deletes all the partitions in the grid that are of type BRT_UNKNOWN and
// all the blobs in them.
void ColPartitionGrid::DeleteUnknownParts(TO_BLOCK* block) {
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
if (part->blob_type() == BRT_UNKNOWN) {
gsearch.RemoveBBox();
// Once marked, the blobs will be swept up by DeleteUnownedNoise.
part->set_flow(BTFT_NONTEXT);
part->set_blob_type(BRT_NOISE);
part->SetBlobTypes();
part->DisownBoxes();
delete part;
}
}
block->DeleteUnownedNoise();
}
// Deletes all the partitions in the grid that are NOT of flow type BTFT_LEADER.
void ColPartitionGrid::DeleteNonLeaderParts() {
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
if (part->flow() != BTFT_LEADER) {
gsearch.RemoveBBox();
if (part->ReleaseNonLeaderBoxes()) {
InsertBBox(true, true, part);
gsearch.RepositionIterator();
} else {
delete part;
}
}
}
}
// Finds and marks text partitions that represent figure captions.
void ColPartitionGrid::FindFigureCaptions() {
// For each image region find its best candidate text caption region,
// if any and mark it as such.
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
if (part->IsImageType()) {
const TBOX& part_box = part->bounding_box();
bool debug = AlignedBlob::WithinTestRegion(2, part_box.left(),
part_box.bottom());
ColPartition* best_caption = NULL;
int best_dist = 0; // Distance to best_caption.
int best_upper = 0; // Direction of best_caption.
// Handle both lower and upper directions.
for (int upper = 0; upper < 2; ++upper) {
ColPartition_C_IT partner_it(upper ? part->upper_partners()
: part->lower_partners());
// If there are no image partners, then this direction is ok.
for (partner_it.mark_cycle_pt(); !partner_it.cycled_list();
partner_it.forward()) {
ColPartition* partner = partner_it.data();
if (partner->IsImageType()) {
break;
}
}
if (!partner_it.cycled_list()) continue;
// Find the nearest totally overlapping text partner.
for (partner_it.mark_cycle_pt(); !partner_it.cycled_list();
partner_it.forward()) {
ColPartition* partner = partner_it.data();
if (!partner->IsTextType() || partner->type() == PT_TABLE) continue;
const TBOX& partner_box = partner->bounding_box();
if (debug) {
tprintf("Finding figure captions for image part:");
part_box.print();
tprintf("Considering partner:");
partner_box.print();
}
if (partner_box.left() >= part_box.left() &&
partner_box.right() <= part_box.right()) {
int dist = partner_box.y_gap(part_box);
if (best_caption == NULL || dist < best_dist) {
best_dist = dist;
best_caption = partner;
best_upper = upper;
}
}
}
}
if (best_caption != NULL) {
if (debug) {
tprintf("Best caption candidate:");
best_caption->bounding_box().print();
}
// We have a candidate caption. Qualify it as being separable from
// any body text. We are looking for either a small number of lines
// or a big gap that indicates a separation from the body text.
int line_count = 0;
int biggest_gap = 0;
int smallest_gap = MAX_INT16;
int total_height = 0;
int mean_height = 0;
ColPartition* end_partner = NULL;
ColPartition* next_partner = NULL;
for (ColPartition* partner = best_caption; partner != NULL &&
line_count <= kMaxCaptionLines;
partner = next_partner) {
if (!partner->IsTextType()) {
end_partner = partner;
break;
}
++line_count;
total_height += partner->bounding_box().height();
next_partner = partner->SingletonPartner(best_upper);
if (next_partner != NULL) {
int gap = partner->bounding_box().y_gap(
next_partner->bounding_box());
if (gap > biggest_gap) {
biggest_gap = gap;
end_partner = next_partner;
mean_height = total_height / line_count;
} else if (gap < smallest_gap) {
smallest_gap = gap;
}
// If the gap looks big compared to the text size and the smallest
// gap seen so far, then we can stop.
if (biggest_gap > mean_height * kMinCaptionGapHeightRatio &&
biggest_gap > smallest_gap * kMinCaptionGapRatio)
break;
}
}
if (debug) {
tprintf("Line count=%d, biggest gap %d, smallest%d, mean height %d\n",
line_count, biggest_gap, smallest_gap, mean_height);
if (end_partner != NULL) {
tprintf("End partner:");
end_partner->bounding_box().print();
}
}
if (next_partner == NULL && line_count <= kMaxCaptionLines)
end_partner = NULL; // No gap, but line count is small.
if (line_count <= kMaxCaptionLines) {
// This is a qualified caption. Mark the text as caption.
for (ColPartition* partner = best_caption; partner != NULL &&
partner != end_partner;
partner = next_partner) {
partner->set_type(PT_CAPTION_TEXT);
partner->SetBlobTypes();
if (debug) {
tprintf("Set caption type for partition:");
partner->bounding_box().print();
}
next_partner = partner->SingletonPartner(best_upper);
}
}
}
}
}
}
//////// 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 ColPartitionGrid::FindPartitionPartners() {
ColPartitionGridSearch gsearch(this);
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
if (part->IsVerticalType()) {
FindVPartitionPartners(true, part);
FindVPartitionPartners(false, part);
} else {
FindPartitionPartners(true, part);
FindPartitionPartners(false, part);
}
}
}
// Finds the best partner in the given direction for the given partition.
// Stores the result with AddPartner.
void ColPartitionGrid::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;
ColPartitionGridSearch vsearch(this);
// 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->WithinSameMargins(*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);
}
// Finds the best partner in the given direction for the given partition.
// Stores the result with AddPartner.
void ColPartitionGrid::FindVPartitionPartners(bool to_the_left,
ColPartition* part) {
if (part->type() == PT_NOISE)
return; // Noise is not allowed to partner anything.
const TBOX& box = part->bounding_box();
int left = part->median_left();
int right = part->median_right();
int width = right - left;
int mid_x = (left + right) / 2;
ColPartitionGridSearch hsearch(this);
// Search left for neighbour to_the_left
hsearch.StartSideSearch(mid_x, box.bottom(), box.top());
ColPartition* neighbour;
ColPartition* best_neighbour = NULL;
int best_dist = MAX_INT32;
while ((neighbour = hsearch.NextSideSearch(to_the_left)) != NULL) {
if (neighbour == part || neighbour->type() == PT_NOISE)
continue; // Noise is not allowed to partner anything.
int neighbour_left = neighbour->median_left();
int neighbour_right = neighbour->median_right();
int neighbour_x = (neighbour_left + neighbour_right) / 2;
if (to_the_left != (neighbour_x < mid_x))
continue;
if (!part->VOverlaps(*neighbour))
continue;
if (!part->TypesMatch(*neighbour))
continue; // Only match to other vertical text.
int dist = to_the_left ? left - neighbour_right : neighbour_left - right;
if (dist <= kMaxPartitionSpacing * width) {
if (dist < best_dist || best_neighbour == NULL) {
best_dist = dist;
best_neighbour = neighbour;
}
} else {
break;
}
}
// For vertical partitions, the upper partner is to the left, and lower is
// to the right.
if (best_neighbour != NULL)
part->AddPartner(to_the_left, best_neighbour);
}
// For every ColPartition with multiple partners in the grid, reduces the
// number of partners to 0 or 1. If get_desperate is true, goes to more
// desperate merge methods to merge flowing text before breaking partnerships.
void ColPartitionGrid::RefinePartitionPartners(bool get_desperate) {
ColPartitionGridSearch gsearch(this);
// Refine in type order so that chasing multiple 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.
gsearch.StartFullSearch();
ColPartition* part;
while ((part = gsearch.NextFullSearch()) != NULL) {
part->RefinePartners(static_cast<PolyBlockType>(type),
get_desperate, this);
// Iterator may have been messed up by a merge.
gsearch.RepositionIterator();
}
}
}
// ========================== PRIVATE CODE ========================
// Finds and returns a list of candidate ColPartitions to merge with part.
// The candidates must overlap search_box, and when merged must not
// overlap any other partitions that are not overlapped by each individually.
void ColPartitionGrid::FindMergeCandidates(const ColPartition* part,
const TBOX& search_box, bool debug,
ColPartition_CLIST* candidates) {
int ok_overlap =
static_cast<int>(kTinyEnoughTextlineOverlapFraction * gridsize() + 0.5);
const TBOX& part_box = part->bounding_box();
// Now run the rect search.
ColPartitionGridSearch rsearch(this);
rsearch.SetUniqueMode(true);
rsearch.StartRectSearch(search_box);
ColPartition* candidate;
while ((candidate = rsearch.NextRectSearch()) != NULL) {
if (!OKMergeCandidate(part, candidate, debug))
continue;
const TBOX& c_box = candidate->bounding_box();
// Candidate seems to be a potential merge with part. If one contains
// the other, then the merge is a no-brainer. Otherwise, search the
// combined box to see if anything else is inappropriately overlapped.
if (!part_box.contains(c_box) && !c_box.contains(part_box)) {
// Search the combined rectangle to see if anything new is overlapped.
// This is a preliminary test designed to quickly weed-out poor
// merge candidates that would create a big list of overlapped objects
// for the squared-order overlap analysis. Eg. vertical and horizontal
// line-like objects that overlap real text when merged:
// || ==========================
// ||
// || r e a l t e x t
// ||
// ||
TBOX merged_box(part_box);
merged_box += c_box;
ColPartitionGridSearch msearch(this);
msearch.SetUniqueMode(true);
msearch.StartRectSearch(merged_box);
ColPartition* neighbour;
while ((neighbour = msearch.NextRectSearch()) != NULL) {
if (neighbour == part || neighbour == candidate)
continue; // Ignore itself.
if (neighbour->OKMergeOverlap(*part, *candidate, ok_overlap, false))
continue; // This kind of merge overlap is OK.
TBOX n_box = neighbour->bounding_box();
// The overlap is OK if:
// * the n_box already overlapped the part or the candidate OR
// * the n_box is a suitable merge with either part or candidate
if (!n_box.overlap(part_box) && !n_box.overlap(c_box) &&
!OKMergeCandidate(part, neighbour, false) &&
!OKMergeCandidate(candidate, neighbour, false))
break;
}
if (neighbour != NULL) {
if (debug) {
tprintf("Combined box overlaps another that is not OK despite"
" allowance of %d:", ok_overlap);
neighbour->bounding_box().print();
tprintf("Reason:");
OKMergeCandidate(part, neighbour, true);
tprintf("...and:");
OKMergeCandidate(candidate, neighbour, true);
tprintf("Overlap:");
neighbour->OKMergeOverlap(*part, *candidate, ok_overlap, true);
}
continue;
}
}
if (debug) {
tprintf("Adding candidate:");
candidate->bounding_box().print();
}
// Unique elements as they arrive.
candidates->add_sorted(SortByBoxLeft<ColPartition>, true, candidate);
}
}
// Smoothes the region type/flow type of the given part by looking at local
// neighbours and the given image mask. Searches a padded rectangle with the
// padding truncated on one size of the part's box in turn for each side,
// using the result (if any) that has the least distance to all neighbours
// that contribute to the decision. This biases in favor of rectangular
// regions without completely enforcing them.
// If a good decision cannot be reached, the part is left unchanged.
// im_box and rerotation are used to map blob coordinates onto the
// nontext_map, which is used to prevent the spread of text neighbourhoods
// into images.
// Returns true if the partition was changed.
bool ColPartitionGrid::SmoothRegionType(Pix* nontext_map,
const TBOX& im_box,
const FCOORD& rerotation,
bool debug,
ColPartition* part) {
const TBOX& part_box = part->bounding_box();
if (debug) {
tprintf("Smooothing part at:");
part_box.print();
}
BlobRegionType best_type = BRT_UNKNOWN;
int best_dist = MAX_INT32;
int max_dist = MIN(part_box.width(), part_box.height());
max_dist = MAX(max_dist * kMaxNeighbourDistFactor, gridsize() * 2);
// Search with the pad truncated on each side of the box in turn.
bool any_image = false;
bool all_image = true;
for (int d = 0; d < BND_COUNT; ++d) {
int dist;
BlobNeighbourDir dir = static_cast<BlobNeighbourDir>(d);
BlobRegionType type = SmoothInOneDirection(dir, nontext_map, im_box,
rerotation, debug, *part,
&dist);
if (debug) {
tprintf("Result in dir %d = %d at dist %d\n", dir, type, dist);
}
if (type != BRT_UNKNOWN && dist < best_dist) {
best_dist = dist;
best_type = type;
}
if (type == BRT_POLYIMAGE)
any_image = true;
else
all_image = false;
}
if (best_dist > max_dist)
return false; // Too far away to set the type with it.
if (part->flow() == BTFT_STRONG_CHAIN && !all_image) {
return false; // We are not modifying it.
}
BlobRegionType new_type = part->blob_type();
BlobTextFlowType new_flow = part->flow();
if (best_type == BRT_TEXT && !any_image) {
new_flow = BTFT_STRONG_CHAIN;
new_type = BRT_TEXT;
} else if (best_type == BRT_VERT_TEXT && !any_image) {
new_flow = BTFT_STRONG_CHAIN;
new_type = BRT_VERT_TEXT;
} else if (best_type == BRT_POLYIMAGE) {
new_flow = BTFT_NONTEXT;
new_type = BRT_UNKNOWN;
}
if (new_type != part->blob_type() || new_flow != part->flow()) {
part->set_flow(new_flow);
part->set_blob_type(new_type);
part->SetBlobTypes();
if (debug) {
tprintf("Modified part:");
part->Print();
}
return true;
} else {
return false;
}
}
// Sets up a search box based on the part_box, padded in all directions
// except direction. Also setup dist_scaling to weight x,y distances according
// to the given direction.
static void ComputeSearchBoxAndScaling(BlobNeighbourDir direction,
const TBOX& part_box,
int min_padding,
TBOX* search_box,
ICOORD* dist_scaling) {
*search_box = part_box;
// Generate a pad value based on the min dimension of part_box, but at least
// min_padding and then scaled by kMaxPadFactor.
int padding = MIN(part_box.height(), part_box.width());
padding = MAX(padding, min_padding);
padding *= kMaxPadFactor;
search_box->pad(padding, padding);
// Truncate the box in the appropriate direction and make the distance
// metric slightly biased in the truncated direction.
switch (direction) {
case BND_LEFT:
search_box->set_left(part_box.left());
*dist_scaling = ICOORD(2, 1);
break;
case BND_BELOW:
search_box->set_bottom(part_box.bottom());
*dist_scaling = ICOORD(1, 2);
break;
case BND_RIGHT:
search_box->set_right(part_box.right());
*dist_scaling = ICOORD(2, 1);
break;
case BND_ABOVE:
search_box->set_top(part_box.top());
*dist_scaling = ICOORD(1, 2);
break;
default:
ASSERT_HOST(false);
}
}
// Local enum used by SmoothInOneDirection and AccumulatePartDistances
// for the different types of partition neighbour.
enum NeighbourPartitionType {
NPT_HTEXT, // Definite horizontal text.
NPT_VTEXT, // Definite vertical text.
NPT_WEAK_HTEXT, // Weakly horizontal text. Counts as HTEXT for HTEXT, but
// image for image and VTEXT.
NPT_WEAK_VTEXT, // Weakly vertical text. Counts as VTEXT for VTEXT, but
// image for image and HTEXT.
NPT_IMAGE, // Defininte non-text.
NPT_COUNT // Number of array elements.
};
// Executes the search for SmoothRegionType in a single direction.
// Creates a bounding box that is padded in all directions except direction,
// and searches it for other partitions. Finds the nearest collection of
// partitions that makes a decisive result (if any) and returns the type
// and the distance of the collection. If there are any pixels in the
// nontext_map, then the decision is biased towards image.
BlobRegionType ColPartitionGrid::SmoothInOneDirection(
BlobNeighbourDir direction, Pix* nontext_map,
const TBOX& im_box, const FCOORD& rerotation,
bool debug, const ColPartition& part, int* best_distance) {
// Set up a rectangle search bounded by the part.
const TBOX& part_box = part.bounding_box();
TBOX search_box;
ICOORD dist_scaling;
ComputeSearchBoxAndScaling(direction, part_box, gridsize(),
&search_box, &dist_scaling);
bool image_region = ImageFind::CountPixelsInRotatedBox(search_box, im_box,
rerotation,
nontext_map) > 0;
GenericVector<int> dists[NPT_COUNT];
AccumulatePartDistances(part, dist_scaling, search_box,
nontext_map, im_box, rerotation, debug, dists);
// By iteratively including the next smallest distance across the vectors,
// (as in a merge sort) we can use the vector indices as counts of each type
// and find the nearest set of objects that give us a definite decision.
int counts[NPT_COUNT];
memset(counts, 0, sizeof(counts[0]) * NPT_COUNT);
// If there is image in the search box, tip the balance in image's favor.
int image_bias = image_region ? kSmoothDecisionMargin / 2 : 0;
BlobRegionType text_dir = part.blob_type();
BlobTextFlowType flow_type = part.flow();
int min_dist = 0;
do {
// Find the minimum new entry across the vectors
min_dist = MAX_INT32;
for (int i = 0; i < NPT_COUNT; ++i) {
if (counts[i] < dists[i].size() && dists[i][counts[i]] < min_dist)
min_dist = dists[i][counts[i]];
}
// Step all the indices/counts forward to include min_dist.
for (int i = 0; i < NPT_COUNT; ++i) {
while (counts[i] < dists[i].size() && dists[i][counts[i]] <= min_dist)
++counts[i];
}
*best_distance = min_dist;
if (debug) {
tprintf("Totals: htext=%d+%d, vtext=%d+%d, image=%d+%d, at dist=%d\n",
counts[NPT_HTEXT], counts[NPT_WEAK_HTEXT],
counts[NPT_VTEXT], counts[NPT_WEAK_VTEXT],
counts[NPT_IMAGE], image_bias, min_dist);
}
// See if we have a decision yet.
int image_count = counts[NPT_IMAGE];
int htext_score = counts[NPT_HTEXT] + counts[NPT_WEAK_HTEXT] -
(image_count + counts[NPT_WEAK_VTEXT]);
int vtext_score = counts[NPT_VTEXT] + counts[NPT_WEAK_VTEXT] -
(image_count + counts[NPT_WEAK_HTEXT]);
if (image_count > 0 &&
image_bias - htext_score >= kSmoothDecisionMargin &&
image_bias - vtext_score >= kSmoothDecisionMargin) {
*best_distance = dists[NPT_IMAGE][0];
if (!dists[NPT_WEAK_VTEXT].empty() &&
*best_distance > dists[NPT_WEAK_VTEXT][0])
*best_distance = dists[NPT_WEAK_VTEXT][0];
if (!dists[NPT_WEAK_HTEXT].empty() &&
*best_distance > dists[NPT_WEAK_HTEXT][0])
*best_distance = dists[NPT_WEAK_HTEXT][0];
return BRT_POLYIMAGE;
}
if ((text_dir != BRT_VERT_TEXT || flow_type != BTFT_CHAIN) &&
counts[NPT_HTEXT] > 0 && htext_score >= kSmoothDecisionMargin) {
*best_distance = dists[NPT_HTEXT][0];
return BRT_TEXT;
} else if ((text_dir != BRT_TEXT || flow_type != BTFT_CHAIN) &&
counts[NPT_VTEXT] > 0 && vtext_score >= kSmoothDecisionMargin) {
*best_distance = dists[NPT_VTEXT][0];
return BRT_VERT_TEXT;
}
} while (min_dist < MAX_INT32);
return BRT_UNKNOWN;
}
// Counts the partitions in the given search_box by appending the gap
// distance (scaled by dist_scaling) of the part from the base_part to the
// vector of the appropriate type for the partition. Prior to return, the
// vectors in the dists array are sorted in increasing order.
// The nontext_map (+im_box, rerotation) is used to make text invisible if
// there is non-text in between.
// dists must be an array of GenericVectors of size NPT_COUNT.
void ColPartitionGrid::AccumulatePartDistances(const ColPartition& base_part,
const ICOORD& dist_scaling,
const TBOX& search_box,
Pix* nontext_map,
const TBOX& im_box,
const FCOORD& rerotation,
bool debug,
GenericVector<int>* dists) {
const TBOX& part_box = base_part.bounding_box();
ColPartitionGridSearch rsearch(this);
rsearch.SetUniqueMode(true);
rsearch.StartRectSearch(search_box);
ColPartition* neighbour;
// Search for compatible neighbours with a similar strokewidth, but not
// on the other side of a tab vector.
while ((neighbour = rsearch.NextRectSearch()) != NULL) {
if (neighbour->IsUnMergeableType() ||
!base_part.ConfirmNoTabViolation(*neighbour) ||
neighbour == &base_part)
continue;
TBOX nbox = neighbour->bounding_box();
BlobRegionType n_type = neighbour->blob_type();
if ((n_type == BRT_TEXT || n_type == BRT_VERT_TEXT) &&
!ImageFind::BlankImageInBetween(part_box, nbox, im_box, rerotation,
nontext_map))
continue; // Text not visible the other side of image.
if (BLOBNBOX::IsLineType(n_type))
continue; // Don't use horizontal lines as neighbours.
int x_gap = MAX(part_box.x_gap(nbox), 0);
int y_gap = MAX(part_box.y_gap(nbox), 0);
int n_dist = x_gap * dist_scaling.x() + y_gap* dist_scaling.y();
if (debug) {
tprintf("Part has x-gap=%d, y=%d, dist=%d at:",
x_gap, y_gap, n_dist);
nbox.print();
}
// Truncate the number of boxes, so text doesn't get too much advantage.
int n_boxes = MIN(neighbour->boxes_count(), kSmoothDecisionMargin);
BlobTextFlowType n_flow = neighbour->flow();
GenericVector<int>* count_vector = NULL;
if (n_flow == BTFT_STRONG_CHAIN) {
if (n_type == BRT_TEXT)
count_vector = &dists[NPT_HTEXT];
else
count_vector = &dists[NPT_VTEXT];
if (debug) {
tprintf("%s %d\n", n_type == BRT_TEXT ? "Htext" : "Vtext", n_boxes);
}
} else if ((n_type == BRT_TEXT || n_type == BRT_VERT_TEXT) &&
(n_flow == BTFT_CHAIN || n_flow == BTFT_NEIGHBOURS)) {
// Medium text counts as weak, and all else counts as image.
if (n_type == BRT_TEXT)
count_vector = &dists[NPT_WEAK_HTEXT];
else
count_vector = &dists[NPT_WEAK_VTEXT];
if (debug) tprintf("Weak %d\n", n_boxes);
} else {
count_vector = &dists[NPT_IMAGE];
if (debug) tprintf("Image %d\n", n_boxes);
}
if (count_vector != NULL) {
for (int i = 0; i < n_boxes; ++i)
count_vector->push_back(n_dist);
}
if (debug) {
neighbour->Print();
}
}
for (int i = 0; i < NPT_COUNT; ++i)
dists[i].sort();
}
// Improves the margins of the part ColPartition by searching for
// neighbours that vertically overlap significantly.
// columns may be NULL, and indicates the assigned column structure this
// is applicable to part.
void ColPartitionGrid::FindPartitionMargins(ColPartitionSet* columns,
ColPartition* part) {
// Set up a rectangle search x-bounded by the column and y by the part.
TBOX box = part->bounding_box();
int y = part->MidY();
// Initial left margin is based on the column, if there is one.
int left_margin = bleft().x();
int right_margin = tright().x();
if (columns != NULL) {
ColPartition* column = columns->ColumnContaining(box.left(), y);
if (column != NULL)
left_margin = column->LeftAtY(y);
column = columns->ColumnContaining(box.right(), y);
if (column != NULL)
right_margin = column->RightAtY(y);
}
left_margin -= kColumnWidthFactor;
right_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);
// 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, up to x_limit, finds
// the margin for the given y range by searching sideways,
// and ignoring not_this.
int ColPartitionGrid::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;
// Iterate the ColPartitions in the grid.
ColPartitionGridSearch side_search(this);
side_search.SetUniqueMode(true);
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) // || part->IsLineType())
continue;
// Must overlap by enough, based on the min of the heights, so
// large partitions can't smash through small ones.
TBOX box = part->bounding_box();
int min_overlap = MIN(height, box.height());
min_overlap = static_cast<int>(min_overlap * kMarginOverlapFraction + 0.5);
int y_overlap = MIN(y_top, box.top()) - MAX(y_bottom, box.bottom());
if (y_overlap < min_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;
}
} // namespace tesseract.
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