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tesseract/textord/tordmain.cpp

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/**********************************************************************
* File: tordmain.cpp (Formerly textordp.c)
* Description: C++ top level textord code.
* Author: Ray Smith
* Created: Tue Jul 28 17:12:33 BST 1992
*
* (C) Copyright 1992, Hewlett-Packard Ltd.
** 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
#ifdef __UNIX__
#include <assert.h>
#endif
#include "stderr.h"
#include "globaloc.h"
#include "blread.h"
#include "blobbox.h"
#include "ccstruct.h"
#include "edgblob.h"
#include "drawtord.h"
#include "makerow.h"
#include "wordseg.h"
#include "textord.h"
#include "tordmain.h"
#include "allheaders.h"
#undef EXTERN
#define EXTERN
#define MAX_NEAREST_DIST 600 //for block skew stats
namespace tesseract {
CLISTIZE(WordWithBox)
/**********************************************************************
* SetBlobStrokeWidth
*
* Set the horizontal and vertical stroke widths in the blob.
**********************************************************************/
void SetBlobStrokeWidth(Pix* pix, BLOBNBOX* blob) {
// Cut the blob rectangle into a Pix.
int pix_height = pixGetHeight(pix);
const TBOX& box = blob->bounding_box();
int width = box.width();
int height = box.height();
Box* blob_pix_box = boxCreate(box.left(), pix_height - box.top(),
width, height);
Pix* pix_blob = pixClipRectangle(pix, blob_pix_box, NULL);
boxDestroy(&blob_pix_box);
Pix* dist_pix = pixDistanceFunction(pix_blob, 4, 8, L_BOUNDARY_BG);
pixDestroy(&pix_blob);
// Compute the stroke widths.
uinT32* data = pixGetData(dist_pix);
int wpl = pixGetWpl(dist_pix);
// Horizontal width of stroke.
STATS h_stats(0, width + 1);
for (int y = 0; y < height; ++y) {
uinT32* pixels = data + y*wpl;
int prev_pixel = 0;
int pixel = GET_DATA_BYTE(pixels, 0);
for (int x = 1; x < width; ++x) {
int next_pixel = GET_DATA_BYTE(pixels, x);
// We are looking for a pixel that is equal to its vertical neighbours,
// yet greater than its left neighbour.
if (prev_pixel < pixel &&
(y == 0 || pixel == GET_DATA_BYTE(pixels - wpl, x - 1)) &&
(y == height - 1 || pixel == GET_DATA_BYTE(pixels + wpl, x - 1))) {
if (pixel > next_pixel) {
// Single local max, so an odd width.
h_stats.add(pixel * 2 - 1, 1);
} else if (pixel == next_pixel && x + 1 < width &&
pixel > GET_DATA_BYTE(pixels, x + 1)) {
// Double local max, so an even width.
h_stats.add(pixel * 2, 1);
}
}
prev_pixel = pixel;
pixel = next_pixel;
}
}
// Vertical width of stroke.
STATS v_stats(0, height + 1);
for (int x = 0; x < width; ++x) {
int prev_pixel = 0;
int pixel = GET_DATA_BYTE(data, x);
for (int y = 1; y < height; ++y) {
uinT32* pixels = data + y*wpl;
int next_pixel = GET_DATA_BYTE(pixels, x);
// We are looking for a pixel that is equal to its horizontal neighbours,
// yet greater than its upper neighbour.
if (prev_pixel < pixel &&
(x == 0 || pixel == GET_DATA_BYTE(pixels - wpl, x - 1)) &&
(x == width - 1 || pixel == GET_DATA_BYTE(pixels - wpl, x + 1))) {
if (pixel > next_pixel) {
// Single local max, so an odd width.
v_stats.add(pixel * 2 - 1, 1);
} else if (pixel == next_pixel && y + 1 < height &&
pixel > GET_DATA_BYTE(pixels + wpl, x)) {
// Double local max, so an even width.
v_stats.add(pixel * 2, 1);
}
}
prev_pixel = pixel;
pixel = next_pixel;
}
}
pixDestroy(&dist_pix);
// Store the horizontal and vertical width in the blob, keeping both
// widths if there is enough information, otherwse only the one with
// the most samples.
// If there are insufficent samples, store zero, rather than using
// 2*area/perimeter, as the numbers that gives do not match the numbers
// from the distance method.
if (h_stats.get_total() >= (width + height) / 4) {
blob->set_horz_stroke_width(h_stats.ile(0.5f));
if (v_stats.get_total() >= (width + height) / 4)
blob->set_vert_stroke_width(v_stats.ile(0.5f));
else
blob->set_vert_stroke_width(0.0f);
} else {
if (v_stats.get_total() >= (width + height) / 4 ||
v_stats.get_total() > h_stats.get_total()) {
blob->set_horz_stroke_width(0.0f);
blob->set_vert_stroke_width(v_stats.ile(0.5f));
} else {
blob->set_horz_stroke_width(h_stats.get_total() > 2 ? h_stats.ile(0.5f)
: 0.0f);
blob->set_vert_stroke_width(0.0f);
}
}
}
/**********************************************************************
* assign_blobs_to_blocks2
*
* Make a list of TO_BLOCKs for portrait and landscape orientation.
**********************************************************************/
void assign_blobs_to_blocks2(Pix* pix,
BLOCK_LIST *blocks, // blocks to process
TO_BLOCK_LIST *port_blocks) { // output list
BLOCK *block; // current block
BLOBNBOX *newblob; // created blob
C_BLOB *blob; // current blob
BLOCK_IT block_it = blocks;
C_BLOB_IT blob_it; // iterator
BLOBNBOX_IT port_box_it; // iterator
// destination iterator
TO_BLOCK_IT port_block_it = port_blocks;
TO_BLOCK *port_block; // created block
for (block_it.mark_cycle_pt(); !block_it.cycled_list(); block_it.forward()) {
block = block_it.data();
port_block = new TO_BLOCK(block);
// Convert the good outlines to block->blob_list
port_box_it.set_to_list(&port_block->blobs);
blob_it.set_to_list(block->blob_list());
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
blob = blob_it.extract();
newblob = new BLOBNBOX(blob); // Convert blob to BLOBNBOX.
SetBlobStrokeWidth(pix, newblob);
port_box_it.add_after_then_move(newblob);
}
// Put the rejected outlines in block->noise_blobs, which allows them to
// be reconsidered and sorted back into rows and recover outlines mistakenly
// rejected.
port_box_it.set_to_list(&port_block->noise_blobs);
blob_it.set_to_list(block->reject_blobs());
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
blob = blob_it.extract();
newblob = new BLOBNBOX(blob); // Convert blob to BLOBNBOX.
SetBlobStrokeWidth(pix, newblob);
port_box_it.add_after_then_move(newblob);
}
port_block_it.add_after_then_move(port_block);
}
}
/**********************************************************************
* find_components
*
* Find the C_OUTLINEs of the connected components in each block, put them
* in C_BLOBs, and filter them by size, putting the different size
* grades on different lists in the matching TO_BLOCK in to_blocks.
**********************************************************************/
void Textord::find_components(Pix* pix, BLOCK_LIST *blocks,
TO_BLOCK_LIST *to_blocks) {
int width = pixGetWidth(pix);
int height = pixGetHeight(pix);
if (width > MAX_INT16 || height > MAX_INT16) {
tprintf("Input image too large! (%d, %d)\n", width, height);
return; // Can't handle it.
}
set_global_loc_code(LOC_EDGE_PROG);
BLOCK_IT block_it(blocks); // iterator
for (block_it.mark_cycle_pt(); !block_it.cycled_list();
block_it.forward()) {
BLOCK* block = block_it.data();
if (block->poly_block() == NULL || block->poly_block()->IsText()) {
extract_edges(pix, block);
}
}
assign_blobs_to_blocks2(pix, blocks, to_blocks);
ICOORD page_tr(width, height);
filter_blobs(page_tr, to_blocks, !textord_test_landscape);
}
/**********************************************************************
* filter_blobs
*
* Sort the blobs into sizes in all the blocks for later work.
**********************************************************************/
void Textord::filter_blobs(ICOORD page_tr, // top right
TO_BLOCK_LIST *blocks, // output list
BOOL8 testing_on) { // for plotting
TO_BLOCK_IT block_it = blocks; // destination iterator
TO_BLOCK *block; // created block
#ifndef GRAPHICS_DISABLED
if (to_win != NULL)
to_win->Clear();
#endif // GRAPHICS_DISABLED
for (block_it.mark_cycle_pt(); !block_it.cycled_list();
block_it.forward()) {
block = block_it.data();
block->line_size = filter_noise_blobs(&block->blobs,
&block->noise_blobs,
&block->small_blobs,
&block->large_blobs);
if (block->line_size == 0) block->line_size = 1;
block->line_spacing = block->line_size *
(tesseract::CCStruct::kDescenderFraction +
tesseract::CCStruct::kXHeightFraction +
2 * tesseract::CCStruct::kAscenderFraction) /
tesseract::CCStruct::kXHeightFraction;
block->line_size *= textord_min_linesize;
block->max_blob_size = block->line_size * textord_excess_blobsize;
#ifndef GRAPHICS_DISABLED
if (textord_show_blobs && testing_on) {
if (to_win == NULL)
create_to_win(page_tr);
block->plot_graded_blobs(to_win);
}
if (textord_show_boxes && testing_on) {
if (to_win == NULL)
create_to_win(page_tr);
plot_box_list(to_win, &block->noise_blobs, ScrollView::WHITE);
plot_box_list(to_win, &block->small_blobs, ScrollView::WHITE);
plot_box_list(to_win, &block->large_blobs, ScrollView::WHITE);
plot_box_list(to_win, &block->blobs, ScrollView::WHITE);
}
#endif // GRAPHICS_DISABLED
}
}
/**********************************************************************
* filter_noise_blobs
*
* Move small blobs to a separate list.
**********************************************************************/
float Textord::filter_noise_blobs(
BLOBNBOX_LIST *src_list, // original list
BLOBNBOX_LIST *noise_list, // noise list
BLOBNBOX_LIST *small_list, // small blobs
BLOBNBOX_LIST *large_list) { // large blobs
inT16 height; //height of blob
inT16 width; //of blob
BLOBNBOX *blob; //current blob
float initial_x; //first guess
BLOBNBOX_IT src_it = src_list; //iterators
BLOBNBOX_IT noise_it = noise_list;
BLOBNBOX_IT small_it = small_list;
BLOBNBOX_IT large_it = large_list;
STATS size_stats (0, MAX_NEAREST_DIST);
//blob heights
float min_y; //size limits
float max_y;
float max_x;
float max_height; //of good blobs
for (src_it.mark_cycle_pt(); !src_it.cycled_list(); src_it.forward()) {
blob = src_it.data();
if (blob->bounding_box().height() < textord_max_noise_size)
noise_it.add_after_then_move(src_it.extract());
else if (blob->enclosed_area() >= blob->bounding_box().height()
* blob->bounding_box().width() * textord_noise_area_ratio)
small_it.add_after_then_move(src_it.extract());
}
for (src_it.mark_cycle_pt(); !src_it.cycled_list(); src_it.forward()) {
size_stats.add(src_it.data()->bounding_box().height(), 1);
}
initial_x = size_stats.ile(textord_initialx_ile);
max_y = ceil(initial_x *
(tesseract::CCStruct::kDescenderFraction +
tesseract::CCStruct::kXHeightFraction +
2 * tesseract::CCStruct::kAscenderFraction) /
tesseract::CCStruct::kXHeightFraction);
min_y = floor (initial_x / 2);
max_x = ceil (initial_x * textord_width_limit);
small_it.move_to_first ();
for (small_it.mark_cycle_pt (); !small_it.cycled_list ();
small_it.forward ()) {
height = small_it.data()->bounding_box().height();
if (height > max_y)
large_it.add_after_then_move(small_it.extract ());
else if (height >= min_y)
src_it.add_after_then_move(small_it.extract ());
}
size_stats.clear ();
for (src_it.mark_cycle_pt (); !src_it.cycled_list (); src_it.forward ()) {
height = src_it.data ()->bounding_box ().height ();
width = src_it.data ()->bounding_box ().width ();
if (height < min_y)
small_it.add_after_then_move (src_it.extract ());
else if (height > max_y || width > max_x)
large_it.add_after_then_move (src_it.extract ());
else
size_stats.add (height, 1);
}
max_height = size_stats.ile (textord_initialasc_ile);
// tprintf("max_y=%g, min_y=%g, initial_x=%g, max_height=%g,",
// max_y,min_y,initial_x,max_height);
max_height *= tesseract::CCStruct::kXHeightCapRatio;
if (max_height > initial_x)
initial_x = max_height;
// tprintf(" ret=%g\n",initial_x);
return initial_x;
}
// Fixes the block so it obeys all the rules:
// Must have at least one ROW.
// Must have at least one WERD.
// WERDs contain a fake blob.
void Textord::cleanup_nontext_block(BLOCK* block) {
// Non-text blocks must contain at least one row.
ROW_IT row_it(block->row_list());
if (row_it.empty()) {
const TBOX& box = block->bounding_box();
float height = box.height();
inT32 xstarts[2] = {box.left(), box.right()};
double coeffs[3] = {0.0, 0.0, static_cast<double>(box.bottom())};
ROW* row = new ROW(1, xstarts, coeffs, height / 2.0f, height / 4.0f,
height / 4.0f, 0, 1);
row_it.add_after_then_move(row);
}
// Each row must contain at least one word.
for (row_it.mark_cycle_pt(); !row_it.cycled_list(); row_it.forward()) {
ROW* row = row_it.data();
WERD_IT w_it(row->word_list());
if (w_it.empty()) {
// Make a fake blob to put in the word.
TBOX box = block->row_list()->singleton() ? block->bounding_box()
: row->bounding_box();
C_BLOB* blob = C_BLOB::FakeBlob(box);
C_BLOB_LIST blobs;
C_BLOB_IT blob_it(&blobs);
blob_it.add_after_then_move(blob);
WERD* word = new WERD(&blobs, 0, NULL);
w_it.add_after_then_move(word);
}
// Each word must contain a fake blob.
for (w_it.mark_cycle_pt(); !w_it.cycled_list(); w_it.forward()) {
WERD* word = w_it.data();
// Just assert that this is true, as it would be useful to find
// out why it isn't.
ASSERT_HOST(!word->cblob_list()->empty());
}
row->recalc_bounding_box();
}
}
/**********************************************************************
* cleanup_blocks
*
* Delete empty blocks, rows from the page.
**********************************************************************/
void Textord::cleanup_blocks(bool clean_noise, BLOCK_LIST* blocks) {
BLOCK_IT block_it = blocks; //iterator
ROW_IT row_it; //row iterator
int num_rows = 0;
int num_rows_all = 0;
int num_blocks = 0;
int num_blocks_all = 0;
for (block_it.mark_cycle_pt(); !block_it.cycled_list();
block_it.forward()) {
BLOCK* block = block_it.data();
if (block->poly_block() != NULL && !block->poly_block()->IsText()) {
cleanup_nontext_block(block);
continue;
}
num_rows = 0;
num_rows_all = 0;
if (clean_noise) {
row_it.set_to_list(block->row_list());
for (row_it.mark_cycle_pt(); !row_it.cycled_list(); row_it.forward()) {
ROW* row = row_it.data();
++num_rows_all;
clean_small_noise_from_words(row);
if ((textord_noise_rejrows && !row->word_list()->empty() &&
clean_noise_from_row(row)) ||
row->word_list()->empty()) {
delete row_it.extract(); // lose empty row.
} else {
if (textord_noise_rejwords)
clean_noise_from_words(row_it.data());
if (textord_blshift_maxshift >= 0)
tweak_row_baseline(row, textord_blshift_maxshift,
textord_blshift_xfraction);
++num_rows;
}
}
}
if (block->row_list()->empty()) {
delete block_it.extract(); // Lose empty text blocks.
} else {
++num_blocks;
}
++num_blocks_all;
if (textord_noise_debug)
tprintf("cleanup_blocks: # rows = %d / %d\n", num_rows, num_rows_all);
}
if (textord_noise_debug)
tprintf("cleanup_blocks: # blocks = %d / %d\n", num_blocks, num_blocks_all);
}
/**********************************************************************
* clean_noise_from_row
*
* Move blobs of words from rows of garbage into the reject blobs list.
**********************************************************************/
BOOL8 Textord::clean_noise_from_row( //remove empties
ROW *row //row to clean
) {
BOOL8 testing_on;
TBOX blob_box; //bounding box
C_BLOB *blob; //current blob
C_OUTLINE *outline; //current outline
WERD *word; //current word
inT32 blob_size; //biggest size
inT32 trans_count = 0; //no of transitions
inT32 trans_threshold; //noise tolerance
inT32 dot_count; //small objects
inT32 norm_count; //normal objects
inT32 super_norm_count; //real char-like
//words of row
WERD_IT word_it = row->word_list ();
C_BLOB_IT blob_it; //blob iterator
C_OUTLINE_IT out_it; //outline iterator
if (textord_test_y > row->base_line (textord_test_x)
&& textord_show_blobs
&& textord_test_y < row->base_line (textord_test_x) + row->x_height ())
testing_on = TRUE;
else
testing_on = FALSE;
dot_count = 0;
norm_count = 0;
super_norm_count = 0;
for (word_it.mark_cycle_pt (); !word_it.cycled_list (); word_it.forward ()) {
word = word_it.data (); //current word
//blobs in word
blob_it.set_to_list (word->cblob_list ());
for (blob_it.mark_cycle_pt (); !blob_it.cycled_list ();
blob_it.forward ()) {
blob = blob_it.data ();
if (!word->flag (W_DONT_CHOP)) {
//get outlines
out_it.set_to_list (blob->out_list ());
for (out_it.mark_cycle_pt (); !out_it.cycled_list ();
out_it.forward ()) {
outline = out_it.data ();
blob_box = outline->bounding_box ();
blob_size =
blob_box.width () >
blob_box.height ()? blob_box.width () : blob_box.
height();
if (blob_size < textord_noise_sizelimit * row->x_height ())
dot_count++; //count smal outlines
if (!outline->child ()->empty ()
&& blob_box.height () <
(1 + textord_noise_syfract) * row->x_height ()
&& blob_box.height () >
(1 - textord_noise_syfract) * row->x_height ()
&& blob_box.width () <
(1 + textord_noise_sxfract) * row->x_height ()
&& blob_box.width () >
(1 - textord_noise_sxfract) * row->x_height ())
super_norm_count++; //count smal outlines
}
}
else
super_norm_count++;
blob_box = blob->bounding_box ();
blob_size =
blob_box.width () >
blob_box.height ()? blob_box.width () : blob_box.height ();
if (blob_size >= textord_noise_sizelimit * row->x_height ()
&& blob_size < row->x_height () * 2) {
trans_threshold = blob_size / textord_noise_sizefraction;
trans_count = blob->count_transitions (trans_threshold);
if (trans_count < textord_noise_translimit)
norm_count++;
}
else if (blob_box.height () > row->x_height () * 2
&& (!word_it.at_first () || !blob_it.at_first ()))
dot_count += 2;
if (testing_on) {
tprintf
("Blob at (%d,%d) -> (%d,%d), ols=%d, tc=%d, bldiff=%g\n",
blob_box.left (), blob_box.bottom (), blob_box.right (),
blob_box.top (), blob->out_list ()->length (), trans_count,
blob_box.bottom () - row->base_line (blob_box.left ()));
}
}
}
if (textord_noise_debug) {
tprintf ("Row ending at (%d,%g):",
blob_box.right (), row->base_line (blob_box.right ()));
tprintf (" R=%g, dc=%d, nc=%d, %s\n",
norm_count > 0 ? (float) dot_count / norm_count : 9999,
dot_count, norm_count,
dot_count > norm_count * textord_noise_normratio
&& dot_count > 2 ? "REJECTED" : "ACCEPTED");
}
return super_norm_count < textord_noise_sncount
&& dot_count > norm_count * textord_noise_rowratio && dot_count > 2;
}
/**********************************************************************
* clean_noise_from_words
*
* Move blobs of words from rows of garbage into the reject blobs list.
**********************************************************************/
void Textord::clean_noise_from_words( //remove empties
ROW *row //row to clean
) {
TBOX blob_box; //bounding box
inT8 *word_dud; //was it chucked
C_BLOB *blob; //current blob
C_OUTLINE *outline; //current outline
WERD *word; //current word
inT32 blob_size; //biggest size
inT32 trans_count; //no of transitions
inT32 trans_threshold; //noise tolerance
inT32 dot_count; //small objects
inT32 norm_count; //normal objects
inT32 dud_words; //number discarded
inT32 ok_words; //number remaining
inT32 word_index; //current word
//words of row
WERD_IT word_it = row->word_list ();
C_BLOB_IT blob_it; //blob iterator
C_OUTLINE_IT out_it; //outline iterator
ok_words = word_it.length ();
if (ok_words == 0 || textord_no_rejects)
return;
word_dud = (inT8 *) alloc_mem (ok_words * sizeof (inT8));
dud_words = 0;
ok_words = 0;
word_index = 0;
for (word_it.mark_cycle_pt (); !word_it.cycled_list (); word_it.forward ()) {
word = word_it.data (); //current word
dot_count = 0;
norm_count = 0;
//blobs in word
blob_it.set_to_list (word->cblob_list ());
for (blob_it.mark_cycle_pt (); !blob_it.cycled_list ();
blob_it.forward ()) {
blob = blob_it.data ();
if (!word->flag (W_DONT_CHOP)) {
//get outlines
out_it.set_to_list (blob->out_list ());
for (out_it.mark_cycle_pt (); !out_it.cycled_list ();
out_it.forward ()) {
outline = out_it.data ();
blob_box = outline->bounding_box ();
blob_size =
blob_box.width () >
blob_box.height ()? blob_box.width () : blob_box.
height();
if (blob_size < textord_noise_sizelimit * row->x_height ())
dot_count++; //count smal outlines
if (!outline->child ()->empty ()
&& blob_box.height () <
(1 + textord_noise_syfract) * row->x_height ()
&& blob_box.height () >
(1 - textord_noise_syfract) * row->x_height ()
&& blob_box.width () <
(1 + textord_noise_sxfract) * row->x_height ()
&& blob_box.width () >
(1 - textord_noise_sxfract) * row->x_height ())
norm_count++; //count smal outlines
}
}
else
norm_count++;
blob_box = blob->bounding_box ();
blob_size =
blob_box.width () >
blob_box.height ()? blob_box.width () : blob_box.height ();
if (blob_size >= textord_noise_sizelimit * row->x_height ()
&& blob_size < row->x_height () * 2) {
trans_threshold = blob_size / textord_noise_sizefraction;
trans_count = blob->count_transitions (trans_threshold);
if (trans_count < textord_noise_translimit)
norm_count++;
}
else if (blob_box.height () > row->x_height () * 2
&& (!word_it.at_first () || !blob_it.at_first ()))
dot_count += 2;
}
if (dot_count > 2 && !word->flag(W_REP_CHAR)) {
if (dot_count > norm_count * textord_noise_normratio * 2)
word_dud[word_index] = 2;
else if (dot_count > norm_count * textord_noise_normratio)
word_dud[word_index] = 1;
else
word_dud[word_index] = 0;
} else {
word_dud[word_index] = 0;
}
if (word_dud[word_index] == 2)
dud_words++;
else
ok_words++;
word_index++;
}
word_index = 0;
for (word_it.mark_cycle_pt (); !word_it.cycled_list (); word_it.forward ()) {
if (word_dud[word_index] == 2
|| (word_dud[word_index] == 1 && dud_words > ok_words)) {
word = word_it.data(); // Current word.
// Previously we threw away the entire word.
// Now just aggressively throw all small blobs into the reject list, where
// the classifier can decide whether they are actually needed.
word->CleanNoise(textord_noise_sizelimit * row->x_height());
}
word_index++;
}
free_mem(word_dud);
}
// Remove outlines that are a tiny fraction in either width or height
// of the word height.
void Textord::clean_small_noise_from_words(ROW *row) {
WERD_IT word_it(row->word_list());
for (word_it.mark_cycle_pt(); !word_it.cycled_list(); word_it.forward()) {
WERD* word = word_it.data();
int min_size = static_cast<int>(
textord_noise_hfract * word->bounding_box().height() + 0.5);
C_BLOB_IT blob_it(word->cblob_list());
for (blob_it.mark_cycle_pt(); !blob_it.cycled_list(); blob_it.forward()) {
C_BLOB* blob = blob_it.data();
C_OUTLINE_IT out_it(blob->out_list());
for (out_it.mark_cycle_pt(); !out_it.cycled_list(); out_it.forward()) {
C_OUTLINE* outline = out_it.data();
outline->RemoveSmallRecursive(min_size, &out_it);
}
if (blob->out_list()->empty()) {
delete blob_it.extract();
}
}
if (word->cblob_list()->empty()) {
if (!word_it.at_last()) {
// The next word is no longer a fuzzy non space if it was before,
// since the word before is about to be deleted.
WERD* next_word = word_it.data_relative(1);
if (next_word->flag(W_FUZZY_NON)) {
next_word->set_flag(W_FUZZY_NON, false);
}
}
delete word_it.extract();
}
}
}
// Local struct to hold a group of blocks.
struct BlockGroup {
BlockGroup() : rotation(1.0f, 0.0f), angle(0.0f), min_xheight(1.0f) {}
explicit BlockGroup(BLOCK* block)
: bounding_box(block->bounding_box()),
rotation(block->re_rotation()),
angle(block->re_rotation().angle()),
min_xheight(block->x_height()) {
blocks.push_back(block);
}
// Union of block bounding boxes.
TBOX bounding_box;
// Common rotation of the blocks.
FCOORD rotation;
// Angle of rotation.
float angle;
// Min xheight of the blocks.
float min_xheight;
// Collection of borrowed pointers to the blocks in the group.
GenericVector<BLOCK*> blocks;
};
// Groups blocks by rotation, then, for each group, makes a WordGrid and calls
// TransferDiacriticsToWords to copy the diacritic blobs to the most
// appropriate words in the group of blocks. Source blobs are not touched.
void Textord::TransferDiacriticsToBlockGroups(BLOBNBOX_LIST* diacritic_blobs,
BLOCK_LIST* blocks) {
// Angle difference larger than this is too much to consider equal.
// They should only be in multiples of M_PI/2 anyway.
const double kMaxAngleDiff = 0.01; // About 0.6 degrees.
PointerVector<BlockGroup> groups;
BLOCK_IT bk_it(blocks);
for (bk_it.mark_cycle_pt(); !bk_it.cycled_list(); bk_it.forward()) {
BLOCK* block = bk_it.data();
if (block->poly_block() != NULL && !block->poly_block()->IsText()) {
continue;
}
// Linear search of the groups to find a matching rotation.
float block_angle = block->re_rotation().angle();
int best_g = 0;
float best_angle_diff = MAX_FLOAT32;
for (int g = 0; g < groups.size(); ++g) {
double angle_diff = fabs(block_angle - groups[g]->angle);
if (angle_diff > M_PI) angle_diff = fabs(angle_diff - 2.0 * M_PI);
if (angle_diff < best_angle_diff) {
best_angle_diff = angle_diff;
best_g = g;
}
}
if (best_angle_diff > kMaxAngleDiff) {
groups.push_back(new BlockGroup(block));
} else {
groups[best_g]->blocks.push_back(block);
groups[best_g]->bounding_box += block->bounding_box();
float x_height = block->x_height();
if (x_height < groups[best_g]->min_xheight)
groups[best_g]->min_xheight = x_height;
}
}
// Now process each group of blocks.
PointerVector<WordWithBox> word_ptrs;
for (int g = 0; g < groups.size(); ++g) {
const BlockGroup* group = groups[g];
if (group->bounding_box.null_box()) continue;
WordGrid word_grid(group->min_xheight, group->bounding_box.botleft(),
group->bounding_box.topright());
for (int b = 0; b < group->blocks.size(); ++b) {
ROW_IT row_it(group->blocks[b]->row_list());
for (row_it.mark_cycle_pt(); !row_it.cycled_list(); row_it.forward()) {
ROW* row = row_it.data();
// Put the words of the row into the grid.
WERD_IT w_it(row->word_list());
for (w_it.mark_cycle_pt(); !w_it.cycled_list(); w_it.forward()) {
WERD* word = w_it.data();
WordWithBox* box_word = new WordWithBox(word);
word_grid.InsertBBox(true, true, box_word);
// Save the pointer where it will be auto-deleted.
word_ptrs.push_back(box_word);
}
}
}
FCOORD rotation = group->rotation;
// Make it a forward rotation that will transform blob coords to block.
rotation.set_y(-rotation.y());
TransferDiacriticsToWords(diacritic_blobs, rotation, &word_grid);
}
}
// Places a copy of blobs that are near a word (after applying rotation to the
// blob) in the most appropriate word, unless there is doubt, in which case a
// blob can end up in two words. Source blobs are not touched.
void Textord::TransferDiacriticsToWords(BLOBNBOX_LIST* diacritic_blobs,
const FCOORD& rotation,
WordGrid* word_grid) {
WordSearch ws(word_grid);
BLOBNBOX_IT b_it(diacritic_blobs);
// Apply rotation to each blob before finding the nearest words. The rotation
// allows us to only consider above/below placement and not left/right on
// vertical text, because all text is horizontal here.
for (b_it.mark_cycle_pt(); !b_it.cycled_list(); b_it.forward()) {
BLOBNBOX* blobnbox = b_it.data();
TBOX blob_box = blobnbox->bounding_box();
blob_box.rotate(rotation);
ws.StartRectSearch(blob_box);
// Above/below refer to word position relative to diacritic. Since some
// scripts eg Kannada/Telugu habitually put diacritics below words, and
// others eg Thai/Vietnamese/Latin put most diacritics above words, try
// for both if there isn't much in it.
WordWithBox* best_above_word = NULL;
WordWithBox* best_below_word = NULL;
int best_above_distance = 0;
int best_below_distance = 0;
for (WordWithBox* word = ws.NextRectSearch(); word != NULL;
word = ws.NextRectSearch()) {
if (word->word()->flag(W_REP_CHAR)) continue;
TBOX word_box = word->true_bounding_box();
int x_distance = blob_box.x_gap(word_box);
int y_distance = blob_box.y_gap(word_box);
if (x_distance > 0) {
// Arbitrarily divide x-distance by 2 if there is a major y overlap,
// and the word is to the left of the diacritic. If the
// diacritic is a dropped broken character between two words, this will
// help send all the pieces to a single word, instead of splitting them
// over the 2 words.
if (word_box.major_y_overlap(blob_box) &&
blob_box.left() > word_box.right()) {
x_distance /= 2;
}
y_distance += x_distance;
}
if (word_box.y_middle() > blob_box.y_middle() &&
(best_above_word == NULL || y_distance < best_above_distance)) {
best_above_word = word;
best_above_distance = y_distance;
}
if (word_box.y_middle() <= blob_box.y_middle() &&
(best_below_word == NULL || y_distance < best_below_distance)) {
best_below_word = word;
best_below_distance = y_distance;
}
}
bool above_good =
best_above_word != NULL &&
(best_below_word == NULL ||
best_above_distance < best_below_distance + blob_box.height());
bool below_good =
best_below_word != NULL && best_below_word != best_above_word &&
(best_above_word == NULL ||
best_below_distance < best_above_distance + blob_box.height());
if (below_good) {
C_BLOB* copied_blob = C_BLOB::deep_copy(blobnbox->cblob());
copied_blob->rotate(rotation);
// Put the blob into the word's reject blobs list.
C_BLOB_IT blob_it(best_below_word->RejBlobs());
blob_it.add_to_end(copied_blob);
}
if (above_good) {
C_BLOB* copied_blob = C_BLOB::deep_copy(blobnbox->cblob());
copied_blob->rotate(rotation);
// Put the blob into the word's reject blobs list.
C_BLOB_IT blob_it(best_above_word->RejBlobs());
blob_it.add_to_end(copied_blob);
}
}
}
} // tesseract
/**********************************************************************
* tweak_row_baseline
*
* Shift baseline to fit the blobs more accurately where they are
* close enough.
**********************************************************************/
void tweak_row_baseline(ROW *row,
double blshift_maxshift,
double blshift_xfraction) {
TBOX blob_box; //bounding box
C_BLOB *blob; //current blob
WERD *word; //current word
inT32 blob_count; //no of blobs
inT32 src_index; //source segment
inT32 dest_index; //destination segment
inT32 *xstarts; //spline segments
double *coeffs; //spline coeffs
float ydiff; //baseline error
float x_centre; //centre of blob
//words of row
WERD_IT word_it = row->word_list ();
C_BLOB_IT blob_it; //blob iterator
blob_count = 0;
for (word_it.mark_cycle_pt (); !word_it.cycled_list (); word_it.forward ()) {
word = word_it.data (); //current word
//get total blobs
blob_count += word->cblob_list ()->length ();
}
if (blob_count == 0)
return;
xstarts =
(inT32 *) alloc_mem ((blob_count + row->baseline.segments + 1) *
sizeof (inT32));
coeffs =
(double *) alloc_mem ((blob_count + row->baseline.segments) * 3 *
sizeof (double));
src_index = 0;
dest_index = 0;
xstarts[0] = row->baseline.xcoords[0];
for (word_it.mark_cycle_pt (); !word_it.cycled_list (); word_it.forward ()) {
word = word_it.data (); //current word
//blobs in word
blob_it.set_to_list (word->cblob_list ());
for (blob_it.mark_cycle_pt (); !blob_it.cycled_list ();
blob_it.forward ()) {
blob = blob_it.data ();
blob_box = blob->bounding_box ();
x_centre = (blob_box.left () + blob_box.right ()) / 2.0;
ydiff = blob_box.bottom () - row->base_line (x_centre);
if (ydiff < 0)
ydiff = -ydiff / row->x_height ();
else
ydiff = ydiff / row->x_height ();
if (ydiff < blshift_maxshift
&& blob_box.height () / row->x_height () > blshift_xfraction) {
if (xstarts[dest_index] >= x_centre)
xstarts[dest_index] = blob_box.left ();
coeffs[dest_index * 3] = 0;
coeffs[dest_index * 3 + 1] = 0;
coeffs[dest_index * 3 + 2] = blob_box.bottom ();
//shift it
dest_index++;
xstarts[dest_index] = blob_box.right () + 1;
}
else {
if (xstarts[dest_index] <= x_centre) {
while (row->baseline.xcoords[src_index + 1] <= x_centre
&& src_index < row->baseline.segments - 1) {
if (row->baseline.xcoords[src_index + 1] >
xstarts[dest_index]) {
coeffs[dest_index * 3] =
row->baseline.quadratics[src_index].a;
coeffs[dest_index * 3 + 1] =
row->baseline.quadratics[src_index].b;
coeffs[dest_index * 3 + 2] =
row->baseline.quadratics[src_index].c;
dest_index++;
xstarts[dest_index] =
row->baseline.xcoords[src_index + 1];
}
src_index++;
}
coeffs[dest_index * 3] =
row->baseline.quadratics[src_index].a;
coeffs[dest_index * 3 + 1] =
row->baseline.quadratics[src_index].b;
coeffs[dest_index * 3 + 2] =
row->baseline.quadratics[src_index].c;
dest_index++;
xstarts[dest_index] = row->baseline.xcoords[src_index + 1];
}
}
}
}
while (src_index < row->baseline.segments
&& row->baseline.xcoords[src_index + 1] <= xstarts[dest_index])
src_index++;
while (src_index < row->baseline.segments) {
coeffs[dest_index * 3] = row->baseline.quadratics[src_index].a;
coeffs[dest_index * 3 + 1] = row->baseline.quadratics[src_index].b;
coeffs[dest_index * 3 + 2] = row->baseline.quadratics[src_index].c;
dest_index++;
src_index++;
xstarts[dest_index] = row->baseline.xcoords[src_index];
}
//turn to spline
row->baseline = QSPLINE (dest_index, xstarts, coeffs);
free_mem(xstarts);
free_mem(coeffs);
}
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