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tesseract/textord/tabfind.cpp

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///////////////////////////////////////////////////////////////////////
// File: TabFind.cpp
// Description: Subclass of BBGrid to find vertically aligned blobs.
// Author: Ray Smith
// Created: Fri Mar 21 15:03:01 PST 2008
//
// (C) Copyright 2008, 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.
//
///////////////////////////////////////////////////////////////////////
#include "tabfind.h"
#include "alignedblob.h"
#include "blobbox.h"
#include "detlinefit.h"
#include "linefind.h"
#include "ndminx.h"
// Include automatically generated configuration file if running autoconf.
#ifdef HAVE_CONFIG_H
#include "config_auto.h"
#endif
namespace tesseract {
// Multiple of box size to search for initial gaps.
const int kTabRadiusFactor = 5;
// Min and Max multiple of height to search vertically when extrapolating.
const int kMinVerticalSearch = 3;
const int kMaxVerticalSearch = 12;
const int kMaxRaggedSearch = 25;
// Minimum number of lines in a column width to make it interesting.
const int kMinLinesInColumn = 10;
// Minimum width of a column to be interesting.
const int kMinColumnWidth = 200;
// Minimum fraction of total column lines for a column to be interesting.
const double kMinFractionalLinesInColumn = 0.125;
// Fraction of height used as alignment tolerance for aligned tabs.
const double kAlignedFraction = 0.03125;
// Minimum gutter width in absolute inch (multiplied by resolution)
const double kMinGutterWidthAbsolute = 0.02;
// Maximum gutter width (in absolute inch) that we care about
const double kMaxGutterWidthAbsolute = 2.00;
// Min aspect ratio of tall objects to be considered a separator line.
// (These will be ignored in searching the gutter for obstructions.)
const double kLineFragmentAspectRatio = 10.0;
// Multiplier of new y positions in running average for skew estimation.
const double kSmoothFactor = 0.25;
// Min coverage for a good baseline between vectors
const double kMinBaselineCoverage = 0.5;
// Minimum overlap fraction when scanning text lines for column widths.
const double kCharVerticalOverlapFraction = 0.375;
// Maximum horizontal gap allowed when scanning for column widths
const double kMaxHorizontalGap = 3.0;
// Maximum upper quartile error allowed on a baseline fit as a fraction
// of height.
const double kMaxBaselineError = 0.4375;
// Min number of points to accept after evaluation.
const int kMinEvaluatedTabs = 3;
// Minimum aspect ratio of a textline to make a good textline blob with a
// single blob.
const int kMaxTextLineBlobRatio = 5;
// Minimum aspect ratio of a textline to make a good textline blob with
// multiple blobs. Target ratio varies according to number of blobs.
const int kMinTextLineBlobRatio = 3;
// Fraction of box area covered by image to make a blob image.
const double kMinImageArea = 0.5;
// Upto 30 degrees is allowed for rotations of diacritic blobs.
// Keep this value slightly larger than kCosSmallAngle in blobbox.cpp
// so that the assert there never fails.
const double kCosMaxSkewAngle = 0.866025;
BOOL_VAR(textord_tabfind_show_initialtabs, false, "Show tab candidates");
BOOL_VAR(textord_tabfind_show_finaltabs, false, "Show tab vectors");
double_VAR(textord_tabfind_aligned_gap_fraction, 0.75,
"Fraction of height used as a minimum gap for aligned blobs.");
TabFind::TabFind(int gridsize, const ICOORD& bleft, const ICOORD& tright,
TabVector_LIST* vlines, int vertical_x, int vertical_y,
int resolution)
: AlignedBlob(gridsize, bleft, tright),
resolution_(resolution),
image_origin_(0, tright.y() - 1),
tab_grid_(new BBGrid<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT>(gridsize,
bleft,
tright)) {
width_cb_ = NULL;
v_it_.set_to_list(&vectors_);
v_it_.add_list_after(vlines);
SetVerticalSkewAndParellelize(vertical_x, vertical_y);
width_cb_ = NewPermanentTessCallback(this, &TabFind::CommonWidth);
}
TabFind::~TabFind() {
delete tab_grid_;
if (width_cb_ != NULL)
delete width_cb_;
}
///////////////// PUBLIC functions (mostly used by TabVector). //////////////
// Insert a list of blobs into the given grid (not necessarily this).
// If take_ownership is true, then the blobs are removed from the source list.
// See InsertBlob for the other arguments.
void TabFind::InsertBlobList(bool h_spread, bool v_spread, bool large,
BLOBNBOX_LIST* blobs, bool take_ownership,
BBGrid<BLOBNBOX, BLOBNBOX_CLIST,
BLOBNBOX_C_IT>* grid) {
BLOBNBOX_IT blob_it(blobs);
int b_count = 0;
int reject_count = 0;
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
BLOBNBOX* blob = blob_it.data();
if (InsertBlob(h_spread, v_spread, large, blob, grid)) {
++b_count;
} else {
++reject_count;
}
if (take_ownership)
blob_it.extract();
}
if (textord_debug_tabfind) {
if (large)
tprintf("Inserted %d large blobs into grid, %d rejected\n",
b_count, reject_count);
else
tprintf("Inserted %d normal blobs into grid\n", b_count);
}
}
// Insert a single blob into the given grid (not necessarily this).
// If h_spread, then all cells covered horizontally by the box are
// used, otherwise, just the bottom-left. Similarly for v_spread.
// If large, then insert only if the bounding box doesn't intersect
// anything else already in the grid. Returns true if the blob was inserted.
// A side effect is that the left and right rule edges of the blob are
// set according to the tab vectors in this (not grid).
bool TabFind::InsertBlob(bool h_spread, bool v_spread, bool large,
BLOBNBOX* blob,
BBGrid<BLOBNBOX, BLOBNBOX_CLIST,
BLOBNBOX_C_IT>* grid) {
TBOX box = blob->bounding_box();
blob->set_left_rule(LeftEdgeForBox(box, false, false));
blob->set_right_rule(RightEdgeForBox(box, false, false));
blob->set_left_crossing_rule(LeftEdgeForBox(box, true, false));
blob->set_right_crossing_rule(RightEdgeForBox(box, true, false));
if (blob->joined_to_prev())
return false;
if (large) {
// Search the grid to see what intersects it.
// Setup a Rectangle search for overlapping this blob.
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> rsearch(grid);
rsearch.StartRectSearch(box);
BLOBNBOX* neighbour = rsearch.NextRectSearch();
if (neighbour != NULL && box.major_overlap(neighbour->bounding_box())) {
if (textord_debug_tabfind) {
TBOX n_box = neighbour->bounding_box();
tprintf("Blob at (%d,%d)->(%d,%d) significantly overlaps blob"
" at (%d,%d)->(%d,%d)\n",
box.left(), box.top(), box.right(), box.bottom(),
n_box.left(), n_box.top(), n_box.right(), n_box.bottom());
}
return false;
}
}
grid->InsertBBox(h_spread, v_spread, blob);
return true;
}
// Returns the gutter width of the given TabVector between the given y limits.
// Also returns x-shift to be added to the vector to clear any intersecting
// blobs. The shift is deducted from the returned gutter.
int TabFind::GutterWidth(int bottom_y, int top_y, const TabVector& v,
int* required_shift) {
bool right_to_left = v.IsLeftTab();
int bottom_x = v.XAtY(bottom_y);
int top_x = v.XAtY(top_y);
int start_x = right_to_left ? MAX(top_x, bottom_x) : MIN(top_x, bottom_x);
BlobGridSearch sidesearch(this);
sidesearch.StartSideSearch(start_x, bottom_y, top_y);
int min_gap = right_to_left ? start_x - bleft().x() : tright().x() - start_x;
*required_shift = 0;
BLOBNBOX* blob = NULL;
while ((blob = sidesearch.NextSideSearch(right_to_left)) != NULL) {
const TBOX& box = blob->bounding_box();
if (box.bottom() >= top_y || box.top() <= bottom_y)
continue; // Doesn't overlap enough.
if (box.height() >= gridsize() * 2 &&
box.height() > box.width() * kLineFragmentAspectRatio) {
// Skip likely separator line residue.
continue;
}
int mid_y = (box.bottom() + box.top()) / 2;
// We use the x at the mid-y so that the required_shift guarantees
// to clear all the blobs on the tab-stop. If we use the min/max
// of x at top/bottom of the blob, then exactness would be required,
// which is not a good thing.
int tab_x = v.XAtY(mid_y);
int gap;
if (right_to_left) {
gap = tab_x - box.right();
if (gap < 0 && box.left() - tab_x < *required_shift)
*required_shift = box.left() - tab_x;
} else {
gap = box.left() - tab_x;
if (gap < 0 && box.right() - tab_x > *required_shift)
*required_shift = box.right() - tab_x;
}
if (gap > 0 && gap < min_gap)
min_gap = gap;
}
// Result may be negative, in which case, this is a really bad tabstop.
return min_gap - abs(*required_shift);
}
// Find the gutter width and distance to inner neighbour for the given blob.
void TabFind::GutterWidthAndNeighbourGap(int tab_x, int mean_height,
int max_gutter, bool left,
BLOBNBOX* bbox, int* gutter_width,
int* neighbour_gap ) {
const TBOX& box = bbox->bounding_box();
int height = box.height();
// The gutter and internal sides of the box.
int gutter_x = left ? box.left() : box.right();
int internal_x = left ? box.right() : box.left();
// On ragged edges, the gutter side of the box is away from the tabstop.
int tab_gap = left ? gutter_x - tab_x : tab_x - gutter_x;
*gutter_width = max_gutter;
// If the box is away from the tabstop, we need to increase
// the allowed gutter width.
if (tab_gap > 0)
*gutter_width += tab_gap;
// Find the nearest blob on the outside of the column.
BLOBNBOX* gutter_bbox = AdjacentBlob(bbox, left, *gutter_width);
if (gutter_bbox != NULL) {
TBOX gutter_box = gutter_bbox->bounding_box();
*gutter_width = left ? tab_x - gutter_box.right()
: gutter_box.left() - tab_x;
}
if (*gutter_width >= max_gutter) {
// If there is no box because a tab was in the way, get the tab coord.
TBOX gutter_box(box);
if (left) {
gutter_box.set_left(tab_x - max_gutter - 1);
gutter_box.set_right(tab_x - max_gutter);
int tab_gutter = RightEdgeForBox(gutter_box, true, false);
if (tab_gutter < tab_x - 1)
*gutter_width = tab_x - tab_gutter;
} else {
gutter_box.set_left(tab_x + max_gutter);
gutter_box.set_right(tab_x + max_gutter + 1);
int tab_gutter = LeftEdgeForBox(gutter_box, true, false);
if (tab_gutter > tab_x + 1)
*gutter_width = tab_gutter - tab_x;
}
}
if (*gutter_width > max_gutter)
*gutter_width = max_gutter;
// Now look for a neighbour on the inside.
BLOBNBOX* neighbour = AdjacentBlob(bbox, !left, *gutter_width);
int neighbour_edge = left ? RightEdgeForBox(box, true, false)
: LeftEdgeForBox(box, true, false);
if (neighbour != NULL) {
TBOX n_box = neighbour->bounding_box();
if (!DifferentSizes(height, n_box.height())) {
if (left && n_box.left() < neighbour_edge)
neighbour_edge = n_box.left();
else if (!left && n_box.right() > neighbour_edge)
neighbour_edge = n_box.right();
}
}
*neighbour_gap = left ? neighbour_edge - internal_x
: internal_x - neighbour_edge;
}
// Find the next adjacent (to left or right) blob on this text line,
// with the constraint that it must vertically significantly overlap
// the input box.
BLOBNBOX* TabFind::AdjacentBlob(const BLOBNBOX* bbox,
bool right_to_left, int gap_limit) {
const TBOX& box = bbox->bounding_box();
return AdjacentBlob(bbox, right_to_left, false, gap_limit,
box.top(), box.bottom());
}
// Compute and return, but do not set the type as being BRT_TEXT or
// BRT_UNKNOWN according to how well it forms a text line.
BlobRegionType TabFind::ComputeBlobType(BLOBNBOX* blob) {
// Check the text line width.
TBOX box = blob->bounding_box();
int blob_count;
int total_blobs;
int width = FindTextlineWidth(true, blob, &total_blobs);
width += FindTextlineWidth(false, blob, &blob_count);
total_blobs += blob_count - 1;
int target_ratio = kMaxTextLineBlobRatio - (total_blobs - 1);
if (target_ratio < kMinTextLineBlobRatio)
target_ratio = kMinTextLineBlobRatio;
BlobRegionType blob_type = (width >= box.height() * target_ratio)
? BRT_TEXT : BRT_UNKNOWN;
if (WithinTestRegion(3, box.left(), box.bottom()))
tprintf("Line width = %d, target = %d, result = %d\n",
width, box.height() * target_ratio, blob_type);
return blob_type;
}
// Return the x-coord that corresponds to the right edge for the given
// box. If there is a rule line to the right that vertically overlaps it,
// then return the x-coord of the rule line, otherwise return the right
// edge of the page. For details see RightTabForBox below.
int TabFind::RightEdgeForBox(const TBOX& box, bool crossing, bool extended) {
TabVector* v = RightTabForBox(box, crossing, extended);
return v == NULL ? tright_.x() : v->XAtY((box.top() + box.bottom()) / 2);
}
// As RightEdgeForBox, but finds the left Edge instead.
int TabFind::LeftEdgeForBox(const TBOX& box, bool crossing, bool extended) {
TabVector* v = LeftTabForBox(box, crossing, extended);
return v == NULL ? bleft_.x() : v->XAtY((box.top() + box.bottom()) / 2);
}
// This comment documents how this function works.
// For its purpose and arguments, see the comment in tabfind.h.
// TabVectors are stored sorted by perpendicular distance of middle from
// the global mean vertical vector. Since the individual vectors can have
// differing directions, their XAtY for a given y is not necessarily in the
// right order. Therefore the search has to be run with a margin.
// The middle of a vector that passes through (x,y) cannot be higher than
// halfway from y to the top, or lower than halfway from y to the bottom
// of the coordinate range; therefore, the search margin is the range of
// sort keys between these halfway points. Any vector with a sort key greater
// than the upper margin must be to the right of x at y, and likewise any
// vector with a sort key less than the lower margin must pass to the left
// of x at y.
TabVector* TabFind::RightTabForBox(const TBOX& box, bool crossing,
bool extended) {
if (v_it_.empty())
return NULL;
int top_y = box.top();
int bottom_y = box.bottom();
int mid_y = (top_y + bottom_y) / 2;
int right = crossing ? (box.left() + box.right()) / 2 : box.right();
int min_key, max_key;
SetupTabSearch(right, mid_y, &min_key, &max_key);
// Position the iterator at the first TabVector with sort_key >= min_key.
while (!v_it_.at_first() && v_it_.data()->sort_key() >= min_key)
v_it_.backward();
while (!v_it_.at_last() && v_it_.data()->sort_key() < min_key)
v_it_.forward();
// Find the leftmost tab vector that overlaps and has XAtY(mid_y) >= right.
TabVector* best_v = NULL;
int best_x = -1;
int key_limit = -1;
do {
TabVector* v = v_it_.data();
int x = v->XAtY(mid_y);
if (x >= right &&
(v->VOverlap(top_y, bottom_y) > 0 ||
(extended && v->ExtendedOverlap(top_y, bottom_y) > 0))) {
if (best_v == NULL || x < best_x) {
best_v = v;
best_x = x;
// We can guarantee that no better vector can be found if the
// sort key exceeds that of the best by max_key - min_key.
key_limit = v->sort_key() + max_key - min_key;
}
}
// Break when the search is done to avoid wrapping the iterator and
// thereby potentially slowing the next search.
if (v_it_.at_last() ||
(best_v != NULL && v->sort_key() > key_limit))
break; // Prevent restarting list for next call.
v_it_.forward();
} while (!v_it_.at_first());
return best_v;
}
// As RightTabForBox, but finds the left TabVector instead.
TabVector* TabFind::LeftTabForBox(const TBOX& box, bool crossing,
bool extended) {
if (v_it_.empty())
return NULL;
int top_y = box.top();
int bottom_y = box.bottom();
int mid_y = (top_y + bottom_y) / 2;
int left = crossing ? (box.left() + box.right()) / 2 : box.left();
int min_key, max_key;
SetupTabSearch(left, mid_y, &min_key, &max_key);
// Position the iterator at the last TabVector with sort_key <= max_key.
while (!v_it_.at_last() && v_it_.data()->sort_key() <= max_key)
v_it_.forward();
while (!v_it_.at_first() && v_it_.data()->sort_key() > max_key) {
v_it_.backward();
}
// Find the rightmost tab vector that overlaps and has XAtY(mid_y) <= left.
TabVector* best_v = NULL;
int best_x = -1;
int key_limit = -1;
do {
TabVector* v = v_it_.data();
int x = v->XAtY(mid_y);
if (x <= left &&
(v->VOverlap(top_y, bottom_y) > 0 ||
(extended && v->ExtendedOverlap(top_y, bottom_y) > 0))) {
if (best_v == NULL || x > best_x) {
best_v = v;
best_x = x;
// We can guarantee that no better vector can be found if the
// sort key is less than that of the best by max_key - min_key.
key_limit = v->sort_key() - (max_key - min_key);
}
}
// Break when the search is done to avoid wrapping the iterator and
// thereby potentially slowing the next search.
if (v_it_.at_first() ||
(best_v != NULL && v->sort_key() < key_limit))
break; // Prevent restarting list for next call.
v_it_.backward();
} while (!v_it_.at_last());
return best_v;
}
// Return true if the given width is close to one of the common
// widths in column_widths_.
bool TabFind::CommonWidth(int width) {
width /= kColumnWidthFactor;
ICOORDELT_IT it(&column_widths_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
ICOORDELT* w = it.data();
if (NearlyEqual<int>(width, w->x(), 1))
return true;
}
return false;
}
// Return true if the sizes are more than a
// factor of 2 different.
bool TabFind::DifferentSizes(int size1, int size2) {
return size1 > size2 * 2 || size2 > size1 * 2;
}
// Return true if the sizes are more than a
// factor of 5 different.
bool TabFind::VeryDifferentSizes(int size1, int size2) {
return size1 > size2 * 5 || size2 > size1 * 5;
}
///////////////// PROTECTED functions (used by ColumnFinder). //////////////
// Top-level function to find TabVectors in an input page block.
// Returns false if the detected skew angle is impossible.
bool TabFind::FindTabVectors(TabVector_LIST* hlines,
BLOBNBOX_LIST* image_blobs, TO_BLOCK* block,
int min_gutter_width,
FCOORD* deskew, FCOORD* reskew) {
ScrollView* tab_win = FindInitialTabVectors(image_blobs, min_gutter_width,
block);
TabVector::MergeSimilarTabVectors(vertical_skew_, &vectors_, this);
SortVectors();
CleanupTabs();
if (!Deskew(hlines, image_blobs, block, deskew, reskew))
return false; // Skew angle is too large.
ApplyTabConstraints();
if (textord_tabfind_show_finaltabs) {
tab_win = MakeWindow(640, 50, "FinalTabs");
if (textord_debug_images) {
tab_win->Image(AlignedBlob::textord_debug_pix().string(),
image_origin_.x(), image_origin_.y());
} else {
DisplayBoxes(tab_win);
DisplayTabs("FinalTabs", tab_win);
}
tab_win = DisplayTabVectors(tab_win);
}
return true;
}
// Top-level function to not find TabVectors in an input page block,
// but setup for single column mode.
void TabFind::DontFindTabVectors(BLOBNBOX_LIST* image_blobs, TO_BLOCK* block,
FCOORD* deskew, FCOORD* reskew) {
InsertBlobList(false, false, false, image_blobs, false, this);
InsertBlobList(true, false, false, &block->blobs, false, this);
deskew->set_x(1.0f);
deskew->set_y(0.0f);
reskew->set_x(1.0f);
reskew->set_y(0.0f);
}
// Helper function to setup search limits for *TabForBox.
void TabFind::SetupTabSearch(int x, int y, int* min_key, int* max_key) {
int key1 = TabVector::SortKey(vertical_skew_, x, (y + tright_.y()) / 2);
int key2 = TabVector::SortKey(vertical_skew_, x, (y + bleft_.y()) / 2);
*min_key = MIN(key1, key2);
*max_key = MAX(key1, key2);
}
ScrollView* TabFind::DisplayTabVectors(ScrollView* tab_win) {
#ifndef GRAPHICS_DISABLED
// For every vector, display it.
TabVector_IT it(&vectors_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
TabVector* vector = it.data();
vector->Display(tab_win);
}
tab_win->Update();
#endif
return tab_win;
}
// PRIVATE CODE.
//
// First part of FindTabVectors, which may be used twice if the text
// is mostly of vertical alignment.
ScrollView* TabFind::FindInitialTabVectors(BLOBNBOX_LIST* image_blobs,
int min_gutter_width,
TO_BLOCK* block) {
if (textord_tabfind_show_initialtabs) {
ScrollView* line_win = MakeWindow(0, 0, "VerticalLines");
line_win = DisplayTabVectors(line_win);
}
// Prepare the grid.
InsertBlobList(false, false, false, image_blobs, false, this);
InsertBlobList(true, false, false, &block->blobs, false, this);
ScrollView* initial_win = FindTabBoxes(min_gutter_width);
FindAllTabVectors(min_gutter_width);
TabVector::MergeSimilarTabVectors(vertical_skew_, &vectors_, this);
SortVectors();
EvaluateTabs();
if (textord_tabfind_show_initialtabs)
initial_win = DisplayTabVectors(initial_win);
ComputeColumnWidths(initial_win);
MarkVerticalText();
return initial_win;
}
// For each box in the grid, decide whether it is a candidate tab-stop,
// and if so add it to the tab_grid_.
ScrollView* TabFind::FindTabBoxes(int min_gutter_width) {
// For every bbox in the grid, determine whether it uses a tab on an edge.
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> gsearch(this);
gsearch.StartFullSearch();
BLOBNBOX* bbox;
while ((bbox = gsearch.NextFullSearch()) != NULL) {
if (TestBoxForTabs(bbox, min_gutter_width)) {
// If it is any kind of tab, insert it into the tab grid.
tab_grid_->InsertBBox(false, false, bbox);
}
}
ScrollView* tab_win = NULL;
if (textord_tabfind_show_initialtabs) {
tab_win = tab_grid_->MakeWindow(0, 100, "InitialTabs");
tab_grid_->DisplayBoxes(tab_win);
tab_win = DisplayTabs("Tabs", tab_win);
}
return tab_win;
}
bool TabFind::TestBoxForTabs(BLOBNBOX* bbox, int min_gutter_width) {
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> radsearch(this);
TBOX box = bbox->bounding_box();
// If there are separator lines, get the column edges.
int left_column_edge = bbox->left_rule();
int right_column_edge = bbox->right_rule();
// The edges of the bounding box of the blob being processed.
int left_x = box.left();
int right_x = box.right();
int top_y = box.top();
int bottom_y = box.bottom();
int height = box.height();
bool debug = WithinTestRegion(3, left_x, top_y);
if (debug) {
tprintf("Column edges for blob at (%d,%d)->(%d,%d) are [%d, %d]\n",
left_x, top_y, right_x, bottom_y,
left_column_edge, right_column_edge);
}
// Compute a search radius based on a multiple of the height.
int radius = (height * kTabRadiusFactor + gridsize_ - 1) / gridsize_;
radsearch.StartRadSearch((left_x + right_x)/2, (top_y + bottom_y)/2, radius);
// In Vertical Page mode, once we have an estimate of the vertical line
// spacing, the minimum amount of gutter space before a possible tab is
// increased under the assumption that column partition is always larger
// than line spacing.
int min_spacing =
static_cast<int>(height * textord_tabfind_aligned_gap_fraction);
if (min_gutter_width > min_spacing)
min_spacing = min_gutter_width;
int target_right = left_x - min_spacing;
int target_left = right_x + min_spacing;
// We will be evaluating whether the left edge could be a left tab, and
// whether the right edge could be a right tab.
// A box can be a tab if its bool is_(left/right)_tab remains true, meaning
// that no blobs have been found in the gutter during the radial search.
// A box can also be a tab if there are objects in the gutter only above
// or only below, and there are aligned objects on the opposite side, but
// not too many unaligned objects. The maybe_(left/right)_tab_up counts
// aligned objects above and negatively counts unaligned objects above,
// and is set to -MAX_INT32 if a gutter object is found above.
// The other 3 maybe ints work similarly for the other sides.
bool is_left_tab = true;
bool is_right_tab = true;
int maybe_left_tab_up = 0;
int maybe_right_tab_up = 0;
int maybe_left_tab_down = 0;
int maybe_right_tab_down = 0;
if (bbox->leader_on_left()) {
is_left_tab = false;
maybe_left_tab_up = -MAX_INT32;
maybe_left_tab_down = -MAX_INT32;
}
if (bbox->leader_on_right()) {
is_right_tab = false;
maybe_right_tab_up = -MAX_INT32;
maybe_right_tab_down = -MAX_INT32;
}
int alignment_tolerance = static_cast<int>(resolution_ * kAlignedFraction);
BLOBNBOX* neighbour = NULL;
while ((neighbour = radsearch.NextRadSearch()) != NULL) {
if (neighbour == bbox)
continue;
TBOX nbox = neighbour->bounding_box();
int n_left = nbox.left();
int n_right = nbox.right();
if (debug)
tprintf("Neighbour at (%d,%d)->(%d,%d)\n",
n_left, nbox.bottom(), n_right, nbox.top());
// If the neighbouring blob is the wrong side of a separator line, then it
// "doesn't exist" as far as we are concerned.
if (n_right > right_column_edge || n_left < left_column_edge ||
left_x < neighbour->left_rule() || right_x > neighbour->right_rule())
continue; // Separator line in the way.
int n_mid_x = (n_left + n_right) / 2;
int n_mid_y = (nbox.top() + nbox.bottom()) / 2;
if (n_mid_x <= left_x && n_right >= target_right) {
if (debug)
tprintf("Not a left tab\n");
is_left_tab = false;
if (n_mid_y < top_y)
maybe_left_tab_down = -MAX_INT32;
if (n_mid_y > bottom_y)
maybe_left_tab_up = -MAX_INT32;
} else if (NearlyEqual(left_x, n_left, alignment_tolerance)) {
if (debug)
tprintf("Maybe a left tab\n");
if (n_mid_y > top_y && maybe_left_tab_up > -MAX_INT32)
++maybe_left_tab_up;
if (n_mid_y < bottom_y && maybe_left_tab_down > -MAX_INT32)
++maybe_left_tab_down;
} else if (n_left < left_x && n_right >= left_x) {
// Overlaps but not aligned so negative points on a maybe.
if (debug)
tprintf("Maybe Not a left tab\n");
if (n_mid_y > top_y && maybe_left_tab_up > -MAX_INT32)
--maybe_left_tab_up;
if (n_mid_y < bottom_y && maybe_left_tab_down > -MAX_INT32)
--maybe_left_tab_down;
}
if (n_mid_x >= right_x && n_left <= target_left) {
if (debug)
tprintf("Not a right tab\n");
is_right_tab = false;
if (n_mid_y < top_y)
maybe_right_tab_down = -MAX_INT32;
if (n_mid_y > bottom_y)
maybe_right_tab_up = -MAX_INT32;
} else if (NearlyEqual(right_x, n_right, alignment_tolerance)) {
if (debug)
tprintf("Maybe a right tab\n");
if (n_mid_y > top_y && maybe_right_tab_up > -MAX_INT32)
++maybe_right_tab_up;
if (n_mid_y < bottom_y && maybe_right_tab_down > -MAX_INT32)
++maybe_right_tab_down;
} else if (n_right > right_x && n_left <= right_x) {
// Overlaps but not aligned so negative points on a maybe.
if (debug)
tprintf("Maybe Not a right tab\n");
if (n_mid_y > top_y && maybe_right_tab_up > -MAX_INT32)
--maybe_right_tab_up;
if (n_mid_y < bottom_y && maybe_right_tab_down > -MAX_INT32)
--maybe_right_tab_down;
}
if (maybe_left_tab_down == -MAX_INT32 && maybe_left_tab_up == -MAX_INT32 &&
maybe_right_tab_down == -MAX_INT32 && maybe_right_tab_up == -MAX_INT32)
break;
}
if (is_left_tab || maybe_left_tab_up > 1 || maybe_left_tab_down > 1) {
if (debug)
tprintf("Setting left tab\n");
bbox->set_left_tab_type(TT_UNCONFIRMED);
}
if (is_right_tab || maybe_right_tab_up > 1 || maybe_right_tab_down > 1) {
if (debug)
tprintf("Setting right tab\n");
bbox->set_right_tab_type(TT_UNCONFIRMED);
}
return bbox->left_tab_type() != TT_NONE || bbox->right_tab_type() != TT_NONE;
}
void TabFind::FindAllTabVectors(int min_gutter_width) {
// A list of vectors that will be created in estimating the skew.
TabVector_LIST dummy_vectors;
// An estimate of the vertical direction, revised as more lines are added.
int vertical_x = 0;
int vertical_y = 1;
// Find an estimate of the vertical direction by finding some tab vectors.
// Slowly up the search size until we get some vectors.
for (int search_size = kMinVerticalSearch; search_size < kMaxVerticalSearch;
search_size += kMinVerticalSearch) {
int vector_count = FindTabVectors(search_size, TA_LEFT_ALIGNED,
min_gutter_width,
&dummy_vectors,
&vertical_x, &vertical_y);
vector_count += FindTabVectors(search_size, TA_RIGHT_ALIGNED,
min_gutter_width,
&dummy_vectors,
&vertical_x, &vertical_y);
if (vector_count > 0)
break;
}
// Get rid of the test vectors and reset the types of the tabs.
dummy_vectors.clear();
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> tsearch(tab_grid_);
BLOBNBOX* bbox;
tsearch.StartFullSearch();
while ((bbox = tsearch.NextFullSearch()) != NULL) {
if (bbox->left_tab_type() == TT_CONFIRMED)
bbox->set_left_tab_type(TT_UNCONFIRMED);
if (bbox->right_tab_type() == TT_CONFIRMED)
bbox->set_right_tab_type(TT_UNCONFIRMED);
}
if (textord_debug_tabfind) {
tprintf("Beginning real tab search with vertical = %d,%d...\n",
vertical_x, vertical_y);
}
// Now do the real thing ,but keep the vectors in the dummy_vectors list
// until they are all done, so we don't get the tab vectors confused with
// the rule line vectors.
FindTabVectors(kMaxVerticalSearch, TA_LEFT_ALIGNED, min_gutter_width,
&dummy_vectors, &vertical_x, &vertical_y);
FindTabVectors(kMaxVerticalSearch, TA_RIGHT_ALIGNED, min_gutter_width,
&dummy_vectors, &vertical_x, &vertical_y);
FindTabVectors(kMaxRaggedSearch, TA_LEFT_RAGGED, min_gutter_width,
&dummy_vectors, &vertical_x, &vertical_y);
FindTabVectors(kMaxRaggedSearch, TA_RIGHT_RAGGED, min_gutter_width,
&dummy_vectors, &vertical_x, &vertical_y);
// Now add the vectors to the vectors_ list.
TabVector_IT v_it(&vectors_);
v_it.add_list_after(&dummy_vectors);
// Now use the summed (mean) vertical vector as the direction for everything.
SetVerticalSkewAndParellelize(vertical_x, vertical_y);
}
// Helper for FindAllTabVectors finds the vectors of a particular type.
int TabFind::FindTabVectors(int search_size_multiple, TabAlignment alignment,
int min_gutter_width, TabVector_LIST* vectors,
int* vertical_x, int* vertical_y) {
TabVector_IT vector_it(vectors);
int vector_count = 0;
// Search the entire tab grid, looking for tab vectors.
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> tsearch(tab_grid_);
BLOBNBOX* bbox;
tsearch.StartFullSearch();
bool right = alignment == TA_RIGHT_ALIGNED || alignment == TA_RIGHT_RAGGED;
while ((bbox = tsearch.NextFullSearch()) != NULL) {
if ((!right && bbox->left_tab_type() == TT_UNCONFIRMED) ||
(right && bbox->right_tab_type() == TT_UNCONFIRMED)) {
TabVector* vector = FindTabVector(search_size_multiple, min_gutter_width,
alignment,
bbox, vertical_x, vertical_y);
if (vector != NULL) {
++vector_count;
vector_it.add_to_end(vector);
}
}
}
return vector_count;
}
// Finds a vector corresponding to a tabstop running through the
// given box of the given alignment type.
// search_size_multiple is a multiple of height used to control
// the size of the search.
// vertical_x and y are updated with an estimate of the real
// vertical direction. (skew finding.)
// Returns NULL if no decent tabstop can be found.
TabVector* TabFind::FindTabVector(int search_size_multiple,
int min_gutter_width,
TabAlignment alignment,
BLOBNBOX* bbox,
int* vertical_x, int* vertical_y) {
AlignedBlobParams align_params(*vertical_x, *vertical_y,
bbox->bounding_box().height(),
search_size_multiple, min_gutter_width,
resolution_, alignment);
// FindVerticalAlignment is in the parent (AlignedBlob) class.
return FindVerticalAlignment(align_params, bbox, vertical_x, vertical_y);
}
// Set the vertical_skew_ member from the given vector and refit
// all vectors parallel to the skew vector.
void TabFind::SetVerticalSkewAndParellelize(int vertical_x, int vertical_y) {
// Fit the vertical vector into an ICOORD, which is 16 bit.
vertical_skew_.set_with_shrink(vertical_x, vertical_y);
if (textord_debug_tabfind)
tprintf("Vertical skew vector=(%d,%d)\n",
vertical_skew_.x(), vertical_skew_.y());
v_it_.set_to_list(&vectors_);
for (v_it_.mark_cycle_pt(); !v_it_.cycled_list(); v_it_.forward()) {
TabVector* v = v_it_.data();
v->Fit(vertical_skew_, true);
}
// Now sort the vectors as their direction has potentially changed.
SortVectors();
}
// Sort all the current vectors using the given vertical direction vector.
void TabFind::SortVectors() {
vectors_.sort(TabVector::SortVectorsByKey);
v_it_.set_to_list(&vectors_);
}
// Evaluate all the current tab vectors.
void TabFind::EvaluateTabs() {
TabVector_IT rule_it(&vectors_);
for (rule_it.mark_cycle_pt(); !rule_it.cycled_list(); rule_it.forward()) {
TabVector* tab = rule_it.data();
if (!tab->IsSeparator()) {
tab->Evaluate(vertical_skew_, this);
if (tab->BoxCount() < kMinEvaluatedTabs) {
if (textord_debug_tabfind > 2)
tab->Print("Too few boxes");
delete rule_it.extract();
v_it_.set_to_list(&vectors_);
} else if (WithinTestRegion(3, tab->startpt().x(), tab->startpt().y())) {
tab->Print("Evaluated tab");
}
}
}
}
// Trace textlines from one side to the other of each tab vector, saving
// the most frequent column widths found in a list so that a given width
// can be tested for being a common width with a simple callback function.
void TabFind::ComputeColumnWidths(ScrollView* tab_win) {
// Set the aligned_text_ member of each blob, so text lines traces
// get terminated where there is a change from text to image.
ComputeBlobGoodness();
if (tab_win != NULL)
tab_win->Pen(ScrollView::WHITE);
// Accumulate column sections into a STATS
int col_widths_size = (tright_.x() - bleft_.x()) /kColumnWidthFactor;
STATS col_widths(0, col_widths_size + 1);
// For every bbox in the tab grid, search for an opposite
// to estimate column width and skew..
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> gsearch(tab_grid_);
gsearch.StartFullSearch();
BLOBNBOX* bbox;
while ((bbox = gsearch.NextFullSearch()) != NULL) {
ICOORD start_pt, end_pt;
if (bbox->left_tab_type() != TT_CONFIRMED &&
bbox->right_tab_type() != TT_CONFIRMED)
continue;
int line_left, line_right;
if (TraceTextline(bbox, &start_pt, &end_pt, &line_left, &line_right)) {
int left_y = (line_left - start_pt.x()) * (end_pt.y() - start_pt.y()) /
(end_pt.x() - start_pt.x()) + start_pt.y();
int right_y = (line_right - start_pt.x()) * (end_pt.y() - start_pt.y()) /
(end_pt.x() - start_pt.x()) + start_pt.y();
if (start_pt.x() != end_pt.x()) {
if (WithinTestRegion(3, start_pt.x(), start_pt.y()))
tprintf("Baseline from (%d,%d) to (%d,%d), started at (%d,%d)\n",
line_left, left_y, line_right, right_y,
bbox->bounding_box().left(), bbox->bounding_box().bottom());
if (tab_win != NULL)
tab_win->Line(line_left, left_y, line_right, right_y);
// If line scan was successful, add to STATS of measurements.
int width = line_right - line_left;
if (width >= kMinColumnWidth) {
col_widths.add(width / kColumnWidthFactor, 1);
}
}
}
}
if (tab_win != NULL) {
tab_win->Update();
}
// Now make a list of column widths.
ICOORDELT_IT w_it(&column_widths_);
int total_col_count = col_widths.get_total();
while (col_widths.get_total() > 0) {
int width = col_widths.mode();
int col_count = col_widths.pile_count(width);
col_widths.add(width, -col_count);
// Get the entire peak.
for (int left = width - 1; left > 0 &&
col_widths.pile_count(left) > 0;
--left) {
int new_count = col_widths.pile_count(left);
col_count += new_count;
col_widths.add(left, -new_count);
}
for (int right = width + 1; right < col_widths_size &&
col_widths.pile_count(right) > 0;
++right) {
int new_count = col_widths.pile_count(right);
col_count += new_count;
col_widths.add(right, -new_count);
}
if (col_count > kMinLinesInColumn &&
col_count > kMinFractionalLinesInColumn * total_col_count) {
ICOORDELT* w = new ICOORDELT(width, col_count);
w_it.add_after_then_move(w);
if (textord_debug_tabfind)
tprintf("Column of width %d has %d = %.2f%% lines\n",
width * kColumnWidthFactor, col_count,
100.0 * col_count / total_col_count);
}
}
}
// Set the region_type_ member for all the blobs in the grid.
void TabFind::ComputeBlobGoodness() {
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> gsearch(this);
gsearch.StartFullSearch();
BLOBNBOX* bbox;
while ((bbox = gsearch.NextFullSearch()) != NULL) {
SetBlobRegionType(bbox);
}
}
// Set the region_type_ member of the blob, if not already known.
void TabFind::SetBlobRegionType(BLOBNBOX* blob) {
// If already set, just return the result.
BlobRegionType blob_type = blob->region_type();
if (blob_type != BRT_UNKNOWN)
return;
// Check for overlapping image blob or other blob already set to image.
TBOX box = blob->bounding_box();
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> rectsearch(this);
rectsearch.StartRectSearch(box);
int rect_overlap = 0;
int poly_overlap = 0;
int text_overlap = 0;
BLOBNBOX* neighbour;
while ((neighbour = rectsearch.NextRectSearch()) != NULL) {
if (neighbour != blob &&
(blob_type = neighbour->region_type()) != BRT_UNKNOWN) {
TBOX nbox = neighbour->bounding_box();
nbox -= box; // This is box intersection, not subtraction.
int area = nbox.area();
if (blob_type == BRT_RECTIMAGE) {
rect_overlap += area;
} else if (blob_type == BRT_POLYIMAGE) {
poly_overlap += area;
} else if (blob_type == BRT_TEXT) {
text_overlap += area;
}
}
}
int area = box.area();
rect_overlap -= text_overlap;
poly_overlap -= text_overlap;
if (rect_overlap >= area || poly_overlap >= area) {
blob->set_region_type(BRT_NOISE); // Make it disappear
} else if (rect_overlap > area * kMinImageArea) {
blob->set_region_type(BRT_RECTIMAGE);
} else if (poly_overlap > area * kMinImageArea) {
blob->set_region_type(BRT_POLYIMAGE);
} else {
// Actually check the text line width.
blob->set_region_type(ComputeBlobType(blob));
}
}
// Mark blobs as being in a vertical text line where that is the case.
// Returns true if the majority of the image is vertical text lines.
void TabFind::MarkVerticalText() {
if (textord_debug_tabfind)
tprintf("Checking for vertical lines\n");
BlobGridSearch gsearch(this);
gsearch.StartFullSearch();
BLOBNBOX* blob = NULL;
while ((blob = gsearch.NextFullSearch()) != NULL) {
if (blob->region_type() < BRT_UNKNOWN)
continue;
if (blob->UniquelyVertical()) {
blob->set_region_type(BRT_VERT_TEXT);
}
}
}
int TabFind::FindMedianGutterWidth(TabVector_LIST *lines) {
TabVector_IT it(lines);
int prev_right = -1;
int max_gap = static_cast<int>(kMaxGutterWidthAbsolute * resolution_);
STATS gaps(0, max_gap);
STATS heights(0, max_gap);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
TabVector* v = it.data();
TabVector* partner = v->GetSinglePartner();
if (!v->IsLeftTab() || v->IsSeparator() || !partner) continue;
heights.add(partner->startpt().x() - v->startpt().x(), 1);
if (prev_right > 0 && v->startpt().x() > prev_right) {
gaps.add(v->startpt().x() - prev_right, 1);
}
prev_right = partner->startpt().x();
}
if (textord_debug_tabfind)
tprintf("TabGutter total %d median_gap %.2f median_hgt %.2f\n",
gaps.get_total(), gaps.median(), heights.median());
if (gaps.get_total() < kMinLinesInColumn) return 0;
return static_cast<int>(gaps.median());
}
// If this box looks like it is on a textline in the given direction,
// return the width of the textline-like group of blobs, and the number
// of blobs found.
// For more detail see FindTextlineSegment below.
int TabFind::FindTextlineWidth(bool right_to_left, BLOBNBOX* bbox,
int* blob_count) {
ICOORD start_pt, end_pt;
BLOBNBOX* left_blob;
BLOBNBOX* right_blob;
return FindTextlineSegment(right_to_left, true, bbox, blob_count,
&start_pt, &end_pt, NULL, NULL,
&left_blob, &right_blob);
}
// Search from the given tabstop bbox to the next opposite
// tabstop bbox on the same text line, which may be itself.
// Returns true if the search is successful, and sets
// start_pt, end_pt to the fitted baseline, width to the measured
// width of the text line (column width estimate.)
bool TabFind::TraceTextline(BLOBNBOX* bbox, ICOORD* start_pt, ICOORD* end_pt,
int* left_edge, int* right_edge) {
bool right_to_left = bbox->left_tab_type() != TT_CONFIRMED;
const TBOX& box = bbox->bounding_box();
TabVector* left_vector = NULL;
TabVector* right_vector = NULL;
if (right_to_left) {
right_vector = RightTabForBox(box, true, false);
if (right_vector == NULL || right_vector->IsLeftTab())
return false;
} else {
left_vector = LeftTabForBox(box, true, false);
if (left_vector == NULL || left_vector->IsRightTab())
return false;
}
BLOBNBOX* left_blob;
BLOBNBOX* right_blob;
int blob_count;
if (FindTextlineSegment(right_to_left, false, bbox, &blob_count,
start_pt, end_pt, &left_vector, &right_vector,
&left_blob, &right_blob)) {
AddPartnerVector(left_blob, right_blob, left_vector, right_vector);
*left_edge = left_vector->XAtY(left_blob->bounding_box().bottom());
*right_edge = right_vector->XAtY(right_blob->bounding_box().bottom());
return true;
}
return false;
}
// Search from the given bbox in the given direction until the next tab
// vector is found or a significant horizontal gap is found.
// Returns the width of the line if the search is successful, (defined
// as good coverage of the width and a good fitting baseline) and sets
// start_pt, end_pt to the fitted baseline, left_blob, right_blob to
// the ends of the line. Returns zero otherwise.
// Sets blob_count to the number of blobs found on the line.
// On input, either both left_vector and right_vector should be NULL,
// indicating a basic search, or both left_vector and right_vector should
// be not NULL and one of *left_vector and *right_vector should be not NULL,
// in which case the search is strictly between tab vectors and will return
// zero if a gap is found before the opposite tab vector is reached, or a
// conflicting tab vector is found.
// If ignore_images is true, then blobs with aligned_text() < 0 are treated
// as if they do not exist.
int TabFind::FindTextlineSegment(bool right_to_left, bool ignore_images,
BLOBNBOX* bbox, int* blob_count,
ICOORD* start_pt, ICOORD* end_pt,
TabVector** left_vector,
TabVector** right_vector,
BLOBNBOX** left_blob, BLOBNBOX** right_blob) {
// Bounding box of the current blob.
TBOX box = bbox->bounding_box();
// The estimates of top and bottom of the current line move in an
// alpha-smoothed manner, but in lock-step.
int top_y = box.top();
int bottom_y = box.bottom();
// Left and right of the current blob.
int left = box.left();
int right = box.right();
// Returning the leftmost and rightmost blob used.
*left_blob = bbox;
*right_blob = bbox;
// Coverage measurement as goodness metric.
int coverage = 0;
// Approximation of the baseline.
DetLineFit linepoints;
// Calculation of the mean height on this line segment.
double total_height = 0.0;
int height_count = 0;
// Starter point for the approximation.
ICOORD first_pt(right_to_left ? right : left, box.bottom());
linepoints.Add(first_pt);
// Last point for the approximation.
ICOORD last_pt = first_pt;
// End coordinate that we must not pass.
int end_coord = right_to_left ? bleft_.x() : tright_.x();
*blob_count = 0;
// Maximum gap allowed before abandoning the search for the other edge.
int gap_limit = static_cast<int>(kMaxHorizontalGap * box.height());
if (WithinTestRegion(3, first_pt.x(), first_pt.y())) {
tprintf("Starting %s line search at (%d, %d-%d)\n",
right_to_left ? "RTL" : "LTR",
left, bottom_y, top_y);
}
while (bbox != NULL) {
int mid_x = (left + right) / 2;
if (right_to_left) {
TabVector* v = LeftTabForBox(box, true, false);
if ((right_vector != NULL && v == *right_vector) ||
(v != NULL && bbox == *right_blob && v->IsRightTab()))
v = LeftTabForBox(box, false, false);
if (right <= end_coord) {
if (WithinTestRegion(3, first_pt.x(), first_pt.y()))
v->Print("Passed through end vector");
break;
}
// No break, so this is a good box.
linepoints.Add(ICOORD(mid_x, box.bottom()));
coverage += box.width();
total_height += box.height();
++height_count;
// In case this is the last one...
*left_blob = bbox;
last_pt.set_x(left);
last_pt.set_y(box.bottom());
if (v != NULL && (right_vector == NULL || v != *right_vector) &&
(bbox != *right_blob || v->IsLeftTab())) {
// The vector is not the starting vector. See if it is within range.
int x_at_y = v->XAtY(bottom_y);
if (x_at_y > left - gap_limit) {
// Once we cross the end_coord, the search will stop.
if (x_at_y > end_coord)
end_coord = x_at_y;
// If this vector is not the correct polarity, then strict searches
// will fail.
if (v->IsLeftTab()) {
if (WithinTestRegion(3, first_pt.x(), first_pt.y()))
v->Print("Hit End Vector!");
if (left_vector != NULL)
*left_vector = v;
} else {
if (WithinTestRegion(3, first_pt.x(), first_pt.y()))
v->Print("Collided with like tab vector");
}
}
}
if (bbox->left_tab_type() == TT_CONFIRMED) {
if (WithinTestRegion(3, first_pt.x(), first_pt.y()))
tprintf("Hit another tab pt\n");
break;
}
} else {
TabVector* v = RightTabForBox(box, true, false);
if ((left_vector != NULL && v == *left_vector) ||
(v != NULL && bbox == *left_blob && v->IsLeftTab()))
v = RightTabForBox(box, false, false);
if (left >= end_coord) {
if (WithinTestRegion(3, first_pt.x(), first_pt.y())) {
tprintf("left=%d, end_coord=%d\n", left, end_coord);
v->Print("Passed through end vector");
}
break;
}
// No break, so this is a good box.
linepoints.Add(ICOORD(mid_x, box.bottom()));
coverage += box.width();
total_height += box.height();
++height_count;
// In case this is the last one...
*right_blob = bbox;
last_pt.set_x(right);
last_pt.set_y(box.bottom());
if (v != NULL && (left_vector == NULL || v != *left_vector) &&
(bbox != *left_blob || v->IsRightTab())) {
// The vector is not the starting vector. See if it is within range.
int x_at_y = v->XAtY(bottom_y);
if (x_at_y < right + gap_limit) {
// Once we cross the end_coord, the search will stop.
if (x_at_y < end_coord)
end_coord = x_at_y;
// If this vector is not the correct polarity, then strict searches
// will fail.
if (v->IsRightTab()) {
if (WithinTestRegion(3, first_pt.x(), first_pt.y()))
v->Print("Hit End Vector!");
if (right_vector != NULL)
*right_vector = v;
} else {
if (WithinTestRegion(3, first_pt.x(), first_pt.y()))
v->Print("Collided with like tab vector");
}
}
}
if (bbox->right_tab_type() == TT_CONFIRMED) {
if (WithinTestRegion(3, first_pt.x(), first_pt.y()))
tprintf("Hit another tab pt\n");
break;
}
}
// Force the top and bottom to stay the same distance apart by
// computing the mean alpha smoothing factor of the top and bottom.
double top_delta = (box.top() - top_y) * kSmoothFactor;
double bottom_delta = (box.bottom() - bottom_y) * kSmoothFactor;
int mean_delta = static_cast<int>((top_delta + bottom_delta) / 2.0);
top_y += mean_delta;
bottom_y += mean_delta;
bbox = AdjacentBlob(bbox, right_to_left, ignore_images,
gap_limit, top_y, bottom_y);
if (bbox != NULL && bbox->region_type() < BRT_UNKNOWN) {
if (WithinTestRegion(3, first_pt.x(), first_pt.y()))
tprintf("Next box is image region\n");
bbox = NULL;
}
if (bbox != NULL) {
box = bbox->bounding_box();
left = box.left();
right = box.right();
if (WithinTestRegion(3, first_pt.x(), first_pt.y()))
tprintf("Next box is at %d, %d\n", left, box.bottom());
}
}
// Either none or both vectors should be NULL.
if (height_count > 0 &&
(left_vector == NULL || *left_vector == NULL) ==
(right_vector == NULL || *right_vector == NULL)) {
linepoints.Add(last_pt);
// Maximum median error allowed to be a good text line.
double max_error = kMaxBaselineError * total_height / height_count;
double error = linepoints.Fit(start_pt, end_pt);
int width = (*right_blob)->bounding_box().right()
- (*left_blob)->bounding_box().left();
bool good_fit = error < max_error && end_pt->x() != start_pt->x() &&
coverage >= kMinBaselineCoverage * width;
if (WithinTestRegion(3, first_pt.x(), first_pt.y())) {
tprintf("Found end! good=%d, error=%g/%g, coverage=%g%%"
" on line (%d, %d) to (%d,%d)\n",
good_fit, error, max_error, 100.0 * coverage / width,
start_pt->x(), start_pt->y(), end_pt->x(), end_pt->y());
tprintf("width=%d, L/R blob=%d/%d, first/last=%d/%d, start/end=%d/%d\n",
width, (*left_blob)->bounding_box().left(),
(*right_blob)->bounding_box().right(),
first_pt.x(), last_pt.x(), start_pt->x(), end_pt->x());
}
*blob_count = height_count;
return good_fit ? width : 0;
}
return 0;
}
// Find the next adjacent (to left or right) blob on this text line,
// with the constraint that it must vertically significantly overlap
// the [top_y, bottom_y] range.
// If ignore_images is true, then blobs with aligned_text() < 0 are treated
// as if they do not exist.
BLOBNBOX* TabFind::AdjacentBlob(const BLOBNBOX* bbox,
bool right_to_left, bool ignore_images,
int gap_limit, int top_y, int bottom_y) {
GridSearch<BLOBNBOX, BLOBNBOX_CLIST, BLOBNBOX_C_IT> sidesearch(this);
const TBOX& box = bbox->bounding_box();
int left = box.left();
int right = box.right();
int mid_x = (left + right) / 2;
sidesearch.StartSideSearch(mid_x, bottom_y, top_y);
int best_gap = 0;
BLOBNBOX* result = NULL;
BLOBNBOX* neighbour = NULL;
while ((neighbour = sidesearch.NextSideSearch(right_to_left)) != NULL) {
if (neighbour == bbox ||
(ignore_images && neighbour->region_type() < BRT_UNKNOWN))
continue;
const TBOX& nbox = neighbour->bounding_box();
int n_top_y = nbox.top();
int n_bottom_y = nbox.bottom();
int v_overlap = MIN(n_top_y, top_y) - MAX(n_bottom_y, bottom_y);
int height = top_y - bottom_y;
int n_height = n_top_y - n_bottom_y;
if (v_overlap > kCharVerticalOverlapFraction * MIN(height, n_height) &&
!DifferentSizes(height, n_height)) {
int n_left = nbox.left();
int n_right = nbox.right();
int h_gap = MAX(n_left, left) - MIN(n_right, right);
int n_mid_x = (n_left + n_right) / 2;
if (right_to_left == (n_mid_x < mid_x) && n_mid_x != mid_x) {
if (h_gap > gap_limit) {
// Hit a big gap before next tab so don't return anything.
if (WithinTestRegion(3, left, n_top_y))
tprintf("Giving up due to big gap = %d vs %d\n",
h_gap, gap_limit);
return result;
}
if ((right_to_left ? neighbour->right_tab_type()
: neighbour->left_tab_type()) >= TT_FAKE) {
// Hit a tab facing the wrong way. Stop in case we are crossing
// the column boundary.
if (WithinTestRegion(3, left, n_top_y))
tprintf("Collision with like tab of type %d at %d,%d\n",
right_to_left ? neighbour->right_tab_type()
: neighbour->left_tab_type(),
n_left, nbox.bottom());
return result;
}
// This is a good fit to the line. Continue with this
// neighbour as the bbox if the best gap.
if (result == NULL || h_gap < best_gap) {
if (WithinTestRegion(3, left, n_top_y))
tprintf("Good result\n");
result = neighbour;
best_gap = h_gap;
} else {
// The new one is worse, so we probably already have the best result.
return result;
}
}
}
}
if (WithinTestRegion(3, left, box.top()))
tprintf("Giving up due to end of search\n");
return result; // Hit the edge and found nothing.
}
// Add a bi-directional partner relationship between the left
// and the right. If one (or both) of the vectors is a separator,
// extend a nearby extendable vector or create a new one of the
// correct type, using the given left or right blob as a guide.
void TabFind::AddPartnerVector(BLOBNBOX* left_blob, BLOBNBOX* right_blob,
TabVector* left, TabVector* right) {
const TBOX& left_box = left_blob->bounding_box();
const TBOX& right_box = right_blob->bounding_box();
if (left->IsSeparator()) {
// Try to find a nearby left edge to extend.
TabVector* v = LeftTabForBox(left_box, true, true);
if (v != NULL && v != left && v->IsLeftTab() &&
v->XAtY(left_box.top()) > left->XAtY(left_box.top())) {
left = v; // Found a good replacement.
left->ExtendToBox(left_blob);
} else {
// Fake a vector.
left = new TabVector(*left, TA_LEFT_RAGGED, vertical_skew_, left_blob);
vectors_.add_sorted(TabVector::SortVectorsByKey, left);
v_it_.move_to_first();
}
}
if (right->IsSeparator()) {
// Try to find a nearby left edge to extend.
if (WithinTestRegion(3, right_box.right(), right_box.bottom())) {
tprintf("Box edge (%d,%d-%d)",
right_box.right(), right_box.bottom(), right_box.top());
right->Print(" looking for improvement for");
}
TabVector* v = RightTabForBox(right_box, true, true);
if (v != NULL && v != right && v->IsRightTab() &&
v->XAtY(right_box.top()) < right->XAtY(right_box.top())) {
right = v; // Found a good replacement.
right->ExtendToBox(right_blob);
if (WithinTestRegion(3, right_box.right(), right_box.bottom())) {
right->Print("Extended vector");
}
} else {
// Fake a vector.
right = new TabVector(*right, TA_RIGHT_RAGGED, vertical_skew_,
right_blob);
vectors_.add_sorted(TabVector::SortVectorsByKey, right);
v_it_.move_to_first();
if (WithinTestRegion(3, right_box.right(), right_box.bottom())) {
right->Print("Created new vector");
}
}
}
left->AddPartner(right);
right->AddPartner(left);
}
// Remove separators and unused tabs from the main vectors_ list
// to the dead_vectors_ list.
void TabFind::CleanupTabs() {
// TODO(rays) Before getting rid of separators and unused vectors, it
// would be useful to try moving ragged vectors outwards to see if this
// allows useful extension. Could be combined with checking ends of partners.
TabVector_IT it(&vectors_);
TabVector_IT dead_it(&dead_vectors_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
TabVector* v = it.data();
if (v->IsSeparator() || v->Partnerless()) {
dead_it.add_after_then_move(it.extract());
v_it_.set_to_list(&vectors_);
} else {
v->FitAndEvaluateIfNeeded(vertical_skew_, this);
}
}
}
// Apply the given rotation to the given list of blobs.
void TabFind::RotateBlobList(const FCOORD& rotation, BLOBNBOX_LIST* blobs) {
BLOBNBOX_IT it(blobs);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
it.data()->rotate_box(rotation);
}
}
// Recreate the grid with deskewed BLOBNBOXes.
// Returns false if the detected skew angle is impossible.
bool TabFind::Deskew(TabVector_LIST* hlines, BLOBNBOX_LIST* image_blobs,
TO_BLOCK* block, FCOORD* deskew, FCOORD* reskew) {
ComputeDeskewVectors(deskew, reskew);
if (deskew->x() < kCosMaxSkewAngle)
return false;
RotateBlobList(*deskew, image_blobs);
RotateBlobList(*deskew, &block->blobs);
RotateBlobList(*deskew, &block->small_blobs);
RotateBlobList(*deskew, &block->noise_blobs);
if (textord_debug_images) {
// Rotate the debug pix and arrange for it to be drawn at the correct
// pixel offset.
Pix* pix_grey = pixRead(AlignedBlob::textord_debug_pix().string());
int width = pixGetWidth(pix_grey);
int height = pixGetHeight(pix_grey);
float angle = atan2(deskew->y(), deskew->x());
// Positive angle is clockwise to pixRotate.
Pix* pix_rot = pixRotate(pix_grey, -angle, L_ROTATE_AREA_MAP,
L_BRING_IN_WHITE, width, height);
// The image must be translated by the rotation of its center, since it
// has just been rotated about its center.
ICOORD center_offset(width / 2, height / 2);
ICOORD new_center_offset(center_offset);
new_center_offset.rotate(*deskew);
image_origin_ += new_center_offset - center_offset;
// The image grew as it was rotated, so offset the (top/left) origin
// by half the change in size. y is opposite to x because it is drawn
// at ist top/left, not bottom/left.
ICOORD corner_offset((width - pixGetWidth(pix_rot)) / 2,
(pixGetHeight(pix_rot) - height) / 2);
image_origin_ += corner_offset;
pixWrite(AlignedBlob::textord_debug_pix().string(), pix_rot, IFF_PNG);
pixDestroy(&pix_grey);
pixDestroy(&pix_rot);
}
// Rotate the horizontal vectors. The vertical vectors don't need
// rotating as they can just be refitted.
TabVector_IT h_it(hlines);
for (h_it.mark_cycle_pt(); !h_it.cycled_list(); h_it.forward()) {
TabVector* h = h_it.data();
h->Rotate(*deskew);
}
TabVector_IT d_it(&dead_vectors_);
for (d_it.mark_cycle_pt(); !d_it.cycled_list(); d_it.forward()) {
TabVector* d = d_it.data();
d->Rotate(*deskew);
}
SetVerticalSkewAndParellelize(0, 1);
// 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());
tab_grid_->Init(gridsize(), grid_box.botleft(), grid_box.topright());
InsertBlobList(false, false, false, image_blobs, false, this);
InsertBlobList(true, false, false, &block->blobs, false, this);
return true;
}
// Flip the vertical and horizontal lines and rotate the grid ready
// for working on the rotated image.
// This also makes parameter adjustments for FindInitialTabVectors().
void TabFind::ResetForVerticalText(const FCOORD& rotate, const FCOORD& rerotate,
TabVector_LIST* horizontal_lines,
int* min_gutter_width) {
// Rotate the horizontal and vertical vectors and swap them over.
// Only the separators are kept and rotated; other tabs are used
// to estimate the gutter width then thrown away.
TabVector_LIST ex_verticals;
TabVector_IT ex_v_it(&ex_verticals);
TabVector_LIST vlines;
TabVector_IT v_it(&vlines);
while (!v_it_.empty()) {
TabVector* v = v_it_.extract();
if (v->IsSeparator()) {
v->Rotate(rotate);
ex_v_it.add_after_then_move(v);
} else {
v_it.add_after_then_move(v);
}
v_it_.forward();
}
// Adjust the min gutter width for better tabbox selection
// in 2nd call to FindInitialTabVectors().
int median_gutter = FindMedianGutterWidth(&vlines);
if (median_gutter > *min_gutter_width)
*min_gutter_width = median_gutter;
TabVector_IT h_it(horizontal_lines);
for (h_it.mark_cycle_pt(); !h_it.cycled_list(); h_it.forward()) {
TabVector* h = h_it.data();
h->Rotate(rotate);
}
v_it_.add_list_after(horizontal_lines);
v_it_.move_to_first();
h_it.set_to_list(horizontal_lines);
h_it.add_list_after(&ex_verticals);
// Rebuild the grid to the new size.
TBOX grid_box(bleft(), tright());
grid_box.rotate_large(rotate);
Init(gridsize(), grid_box.botleft(), grid_box.topright());
tab_grid_->Init(gridsize(), grid_box.botleft(), grid_box.topright());
column_widths_.clear();
}
// Compute the rotation required to deskew, and its inverse rotation.
void TabFind::ComputeDeskewVectors(FCOORD* deskew, FCOORD* reskew) {
double length = vertical_skew_ % vertical_skew_;
length = sqrt(length);
deskew->set_x(static_cast<float>(vertical_skew_.y() / length));
deskew->set_y(static_cast<float>(vertical_skew_.x() / length));
reskew->set_x(deskew->x());
reskew->set_y(-deskew->y());
}
// Compute and apply constraints to the end positions of TabVectors so
// that where possible partners end at the same y coordinate.
void TabFind::ApplyTabConstraints() {
TabVector_IT it(&vectors_);
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
TabVector* v = it.data();
v->SetupConstraints();
}
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
TabVector* v = it.data();
// With the first and last partner, we want a common bottom and top,
// respectively, and for each change of partner, we want a common
// top of first with bottom of next.
v->SetupPartnerConstraints();
}
// TODO(rays) The back-to-back pairs should really be done like the
// front-to-front pairs, but there is no convenient way of producing the
// list of partners like there is with the front-to-front.
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
TabVector* v = it.data();
if (!v->IsRightTab())
continue;
// For each back-to-back pair of vectors, try for common top and bottom.
TabVector_IT partner_it(it);
for (partner_it.forward(); !partner_it.at_first(); partner_it.forward()) {
TabVector* partner = partner_it.data();
if (!partner->IsLeftTab() || !v->VOverlap(*partner))
continue;
v->SetupPartnerConstraints(partner);
}
}
// Now actually apply the constraints to get common start/end points.
for (it.mark_cycle_pt(); !it.cycled_list(); it.forward()) {
TabVector* v = it.data();
if (!v->IsSeparator())
v->ApplyConstraints();
}
// TODO(rays) Where constraint application fails, it would be good to try
// checking the ends to see if they really should be moved.
}
} // namespace tesseract.
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