/
osdetect.cpp
579 lines (522 loc) · 19.8 KB
/
osdetect.cpp
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
///////////////////////////////////////////////////////////////////////
// File: osdetect.cpp
// Description: Orientation and script detection.
// Author: Samuel Charron
// Ranjith Unnikrishnan
//
// (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 <algorithm>
#include <cmath> // for std::fabs
#include <memory>
#include "osdetect.h"
#include "blobbox.h"
#include "blread.h"
#include "colfind.h"
#include "fontinfo.h"
#include "imagefind.h"
#include "linefind.h"
#include "oldlist.h"
#include "qrsequence.h"
#include "ratngs.h"
#include "strngs.h"
#include "tabvector.h"
#include "tesseractclass.h"
#include "textord.h"
const float kSizeRatioToReject = 2.0;
const int kMinAcceptableBlobHeight = 10;
const float kScriptAcceptRatio = 1.3;
const float kHanRatioInKorean = 0.7;
const float kHanRatioInJapanese = 0.3;
const float kNonAmbiguousMargin = 1.0;
// General scripts
static const char* han_script = "Han";
static const char* latin_script = "Latin";
static const char* katakana_script = "Katakana";
static const char* hiragana_script = "Hiragana";
static const char* hangul_script = "Hangul";
// Pseudo-scripts Name
const char* ScriptDetector::korean_script_ = "Korean";
const char* ScriptDetector::japanese_script_ = "Japanese";
const char* ScriptDetector::fraktur_script_ = "Fraktur";
void OSResults::update_best_orientation() {
float first = orientations[0];
float second = orientations[1];
best_result.orientation_id = 0;
if (orientations[0] < orientations[1]) {
first = orientations[1];
second = orientations[0];
best_result.orientation_id = 1;
}
for (int i = 2; i < 4; ++i) {
if (orientations[i] > first) {
second = first;
first = orientations[i];
best_result.orientation_id = i;
} else if (orientations[i] > second) {
second = orientations[i];
}
}
// Store difference of top two orientation scores.
best_result.oconfidence = first - second;
}
void OSResults::set_best_orientation(int orientation_id) {
best_result.orientation_id = orientation_id;
best_result.oconfidence = 0;
}
void OSResults::update_best_script(int orientation) {
// We skip index 0 to ignore the "Common" script.
float first = scripts_na[orientation][1];
float second = scripts_na[orientation][2];
best_result.script_id = 1;
if (scripts_na[orientation][1] < scripts_na[orientation][2]) {
first = scripts_na[orientation][2];
second = scripts_na[orientation][1];
best_result.script_id = 2;
}
for (int i = 3; i < kMaxNumberOfScripts; ++i) {
if (scripts_na[orientation][i] > first) {
best_result.script_id = i;
second = first;
first = scripts_na[orientation][i];
} else if (scripts_na[orientation][i] > second) {
second = scripts_na[orientation][i];
}
}
best_result.sconfidence =
(first / second - 1.0) / (kScriptAcceptRatio - 1.0);
}
int OSResults::get_best_script(int orientation_id) const {
int max_id = -1;
for (int j = 0; j < kMaxNumberOfScripts; ++j) {
const char *script = unicharset->get_script_from_script_id(j);
if (strcmp(script, "Common") && strcmp(script, "NULL")) {
if (max_id == -1 ||
scripts_na[orientation_id][j] > scripts_na[orientation_id][max_id])
max_id = j;
}
}
return max_id;
}
// Print the script scores for all possible orientations.
void OSResults::print_scores(void) const {
for (int i = 0; i < 4; ++i) {
tprintf("Orientation id #%d", i);
print_scores(i);
}
}
// Print the script scores for the given candidate orientation.
void OSResults::print_scores(int orientation_id) const {
for (int j = 0; j < kMaxNumberOfScripts; ++j) {
if (scripts_na[orientation_id][j]) {
tprintf("%12s\t: %f\n", unicharset->get_script_from_script_id(j),
scripts_na[orientation_id][j]);
}
}
}
// Accumulate scores with given OSResults instance and update the best script.
void OSResults::accumulate(const OSResults& osr) {
for (int i = 0; i < 4; ++i) {
orientations[i] += osr.orientations[i];
for (int j = 0; j < kMaxNumberOfScripts; ++j)
scripts_na[i][j] += osr.scripts_na[i][j];
}
unicharset = osr.unicharset;
update_best_orientation();
update_best_script(best_result.orientation_id);
}
// Detect and erase horizontal/vertical lines and picture regions from the
// image, so that non-text blobs are removed from consideration.
static void remove_nontext_regions(tesseract::Tesseract *tess,
BLOCK_LIST *blocks,
TO_BLOCK_LIST *to_blocks) {
Pix *pix = tess->pix_binary();
ASSERT_HOST(pix != nullptr);
int vertical_x = 0;
int vertical_y = 1;
tesseract::TabVector_LIST v_lines;
tesseract::TabVector_LIST h_lines;
int resolution;
if (kMinCredibleResolution > pixGetXRes(pix)) {
resolution = kMinCredibleResolution;
tprintf("Warning. Invalid resolution %d dpi. Using %d instead.\n",
pixGetXRes(pix), resolution);
} else {
resolution = pixGetXRes(pix);
}
tesseract::LineFinder::FindAndRemoveLines(resolution, false, pix,
&vertical_x, &vertical_y,
nullptr, &v_lines, &h_lines);
Pix* im_pix = tesseract::ImageFind::FindImages(pix, nullptr);
if (im_pix != nullptr) {
pixSubtract(pix, pix, im_pix);
pixDestroy(&im_pix);
}
tess->mutable_textord()->find_components(tess->pix_binary(),
blocks, to_blocks);
}
// Find connected components in the page and process a subset until finished or
// a stopping criterion is met.
// Returns the number of blobs used in making the estimate. 0 implies failure.
int orientation_and_script_detection(STRING& filename,
OSResults* osr,
tesseract::Tesseract* tess) {
STRING name = filename; //truncated name
const char *lastdot; //of name
TBOX page_box;
lastdot = strrchr (name.string (), '.');
if (lastdot != nullptr)
name[lastdot-name.string()] = '\0';
ASSERT_HOST(tess->pix_binary() != nullptr);
int width = pixGetWidth(tess->pix_binary());
int height = pixGetHeight(tess->pix_binary());
BLOCK_LIST blocks;
if (!read_unlv_file(name, width, height, &blocks))
FullPageBlock(width, height, &blocks);
// Try to remove non-text regions from consideration.
TO_BLOCK_LIST land_blocks, port_blocks;
remove_nontext_regions(tess, &blocks, &port_blocks);
if (port_blocks.empty()) {
// page segmentation did not succeed, so we need to find_components first.
tess->mutable_textord()->find_components(tess->pix_binary(),
&blocks, &port_blocks);
} else {
page_box.set_left(0);
page_box.set_bottom(0);
page_box.set_right(width);
page_box.set_top(height);
// Filter_blobs sets up the TO_BLOCKs the same as find_components does.
tess->mutable_textord()->filter_blobs(page_box.topright(),
&port_blocks, true);
}
return os_detect(&port_blocks, osr, tess);
}
// Filter and sample the blobs.
// Returns a non-zero number of blobs if the page was successfully processed, or
// zero if the page had too few characters to be reliable
int os_detect(TO_BLOCK_LIST* port_blocks, OSResults* osr,
tesseract::Tesseract* tess) {
int blobs_total = 0;
TO_BLOCK_IT block_it;
block_it.set_to_list(port_blocks);
BLOBNBOX_CLIST filtered_list;
BLOBNBOX_C_IT filtered_it(&filtered_list);
for (block_it.mark_cycle_pt(); !block_it.cycled_list();
block_it.forward ()) {
TO_BLOCK* to_block = block_it.data();
if (to_block->block->pdblk.poly_block() &&
!to_block->block->pdblk.poly_block()->IsText()) continue;
BLOBNBOX_IT bbox_it;
bbox_it.set_to_list(&to_block->blobs);
for (bbox_it.mark_cycle_pt (); !bbox_it.cycled_list ();
bbox_it.forward ()) {
BLOBNBOX* bbox = bbox_it.data();
C_BLOB* blob = bbox->cblob();
TBOX box = blob->bounding_box();
++blobs_total;
// Catch illegal value of box width and avoid division by zero.
if (box.width() == 0) continue;
// TODO: Can height and width be negative? If not, remove fabs.
float y_x = std::fabs((box.height() * 1.0f) / box.width());
float x_y = 1.0f / y_x;
// Select a >= 1.0 ratio
float ratio = x_y > y_x ? x_y : y_x;
// Blob is ambiguous
if (ratio > kSizeRatioToReject) continue;
if (box.height() < kMinAcceptableBlobHeight) continue;
filtered_it.add_to_end(bbox);
}
}
return os_detect_blobs(nullptr, &filtered_list, osr, tess);
}
// Detect orientation and script from a list of blobs.
// Returns a non-zero number of blobs if the list was successfully processed, or
// zero if the list had too few characters to be reliable.
// If allowed_scripts is non-null and non-empty, it is a list of scripts that
// constrains both orientation and script detection to consider only scripts
// from the list.
int os_detect_blobs(const GenericVector<int>* allowed_scripts,
BLOBNBOX_CLIST* blob_list, OSResults* osr,
tesseract::Tesseract* tess) {
OSResults osr_;
int minCharactersToTry = tess->min_characters_to_try;
int maxCharactersToTry = 5 * minCharactersToTry;
if (osr == nullptr)
osr = &osr_;
osr->unicharset = &tess->unicharset;
OrientationDetector o(allowed_scripts, osr);
ScriptDetector s(allowed_scripts, osr, tess);
BLOBNBOX_C_IT filtered_it(blob_list);
int real_max = std::min(filtered_it.length(), maxCharactersToTry);
// tprintf("Total blobs found = %d\n", blobs_total);
// tprintf("Number of blobs post-filtering = %d\n", filtered_it.length());
// tprintf("Number of blobs to try = %d\n", real_max);
// If there are too few characters, skip this page entirely.
if (real_max < minCharactersToTry / 2) {
tprintf("Too few characters. Skipping this page\n");
return 0;
}
auto** blobs = new BLOBNBOX*[filtered_it.length()];
int number_of_blobs = 0;
for (filtered_it.mark_cycle_pt (); !filtered_it.cycled_list ();
filtered_it.forward ()) {
blobs[number_of_blobs++] = (BLOBNBOX*)filtered_it.data();
}
QRSequenceGenerator sequence(number_of_blobs);
int num_blobs_evaluated = 0;
for (int i = 0; i < real_max; ++i) {
if (os_detect_blob(blobs[sequence.GetVal()], &o, &s, osr, tess)
&& i > minCharactersToTry) {
break;
}
++num_blobs_evaluated;
}
delete [] blobs;
// Make sure the best_result is up-to-date
int orientation = o.get_orientation();
osr->update_best_script(orientation);
return num_blobs_evaluated;
}
// Processes a single blob to estimate script and orientation.
// Return true if estimate of orientation and script satisfies stopping
// criteria.
bool os_detect_blob(BLOBNBOX* bbox, OrientationDetector* o,
ScriptDetector* s, OSResults* osr,
tesseract::Tesseract* tess) {
tess->tess_cn_matching.set_value(true); // turn it on
tess->tess_bn_matching.set_value(false);
C_BLOB* blob = bbox->cblob();
TBLOB* tblob = TBLOB::PolygonalCopy(tess->poly_allow_detailed_fx, blob);
TBOX box = tblob->bounding_box();
FCOORD current_rotation(1.0f, 0.0f);
FCOORD rotation90(0.0f, 1.0f);
BLOB_CHOICE_LIST ratings[4];
// Test the 4 orientations
for (int i = 0; i < 4; ++i) {
// Normalize the blob. Set the origin to the place we want to be the
// bottom-middle after rotation.
// Scaling is to make the rotated height the x-height.
float scaling = static_cast<float>(kBlnXHeight) / box.height();
float x_origin = (box.left() + box.right()) / 2.0f;
float y_origin = (box.bottom() + box.top()) / 2.0f;
if (i == 0 || i == 2) {
// Rotation is 0 or 180.
y_origin = i == 0 ? box.bottom() : box.top();
} else {
// Rotation is 90 or 270.
scaling = static_cast<float>(kBlnXHeight) / box.width();
x_origin = i == 1 ? box.left() : box.right();
}
std::unique_ptr<TBLOB> rotated_blob(new TBLOB(*tblob));
rotated_blob->Normalize(nullptr, ¤t_rotation, nullptr,
x_origin, y_origin, scaling, scaling,
0.0f, static_cast<float>(kBlnBaselineOffset),
false, nullptr);
tess->AdaptiveClassifier(rotated_blob.get(), ratings + i);
current_rotation.rotate(rotation90);
}
delete tblob;
bool stop = o->detect_blob(ratings);
s->detect_blob(ratings);
int orientation = o->get_orientation();
stop = s->must_stop(orientation) && stop;
return stop;
}
OrientationDetector::OrientationDetector(
const GenericVector<int>* allowed_scripts, OSResults* osr) {
osr_ = osr;
allowed_scripts_ = allowed_scripts;
}
// Score the given blob and return true if it is now sure of the orientation
// after adding this block.
bool OrientationDetector::detect_blob(BLOB_CHOICE_LIST* scores) {
float blob_o_score[4] = {0.0f, 0.0f, 0.0f, 0.0f};
float total_blob_o_score = 0.0f;
for (int i = 0; i < 4; ++i) {
BLOB_CHOICE_IT choice_it(scores + i);
if (!choice_it.empty()) {
BLOB_CHOICE* choice = nullptr;
if (allowed_scripts_ != nullptr && !allowed_scripts_->empty()) {
// Find the top choice in an allowed script.
for (choice_it.mark_cycle_pt(); !choice_it.cycled_list() &&
choice == nullptr; choice_it.forward()) {
int choice_script = choice_it.data()->script_id();
int s = 0;
for (s = 0; s < allowed_scripts_->size(); ++s) {
if ((*allowed_scripts_)[s] == choice_script) {
choice = choice_it.data();
break;
}
}
}
} else {
choice = choice_it.data();
}
if (choice != nullptr) {
// The certainty score ranges between [-20,0]. This is converted here to
// [0,1], with 1 indicating best match.
blob_o_score[i] = 1 + 0.05 * choice->certainty();
total_blob_o_score += blob_o_score[i];
}
}
}
if (total_blob_o_score == 0.0) return false;
// Fill in any blanks with the worst score of the others. This is better than
// picking an arbitrary probability for it and way better than -inf.
float worst_score = 0.0f;
int num_good_scores = 0;
for (float f : blob_o_score) {
if (f > 0.0f) {
++num_good_scores;
if (worst_score == 0.0f || f < worst_score)
worst_score = f;
}
}
if (num_good_scores == 1) {
// Lower worst if there is only one.
worst_score /= 2.0f;
}
for (float& f : blob_o_score) {
if (f == 0.0f) {
f = worst_score;
total_blob_o_score += worst_score;
}
}
// Normalize the orientation scores for the blob and use them to
// update the aggregated orientation score.
for (int i = 0; total_blob_o_score != 0 && i < 4; ++i) {
osr_->orientations[i] += log(blob_o_score[i] / total_blob_o_score);
}
// TODO(ranjith) Add an early exit test, based on min_orientation_margin,
// as used in pagesegmain.cpp.
return false;
}
int OrientationDetector::get_orientation() {
osr_->update_best_orientation();
return osr_->best_result.orientation_id;
}
ScriptDetector::ScriptDetector(const GenericVector<int>* allowed_scripts,
OSResults* osr, tesseract::Tesseract* tess) {
osr_ = osr;
tess_ = tess;
allowed_scripts_ = allowed_scripts;
katakana_id_ = tess_->unicharset.add_script(katakana_script);
hiragana_id_ = tess_->unicharset.add_script(hiragana_script);
han_id_ = tess_->unicharset.add_script(han_script);
hangul_id_ = tess_->unicharset.add_script(hangul_script);
japanese_id_ = tess_->unicharset.add_script(japanese_script_);
korean_id_ = tess_->unicharset.add_script(korean_script_);
latin_id_ = tess_->unicharset.add_script(latin_script);
fraktur_id_ = tess_->unicharset.add_script(fraktur_script_);
}
// Score the given blob and return true if it is now sure of the script after
// adding this blob.
void ScriptDetector::detect_blob(BLOB_CHOICE_LIST* scores) {
for (int i = 0; i < 4; ++i) {
bool done[kMaxNumberOfScripts] = { false };
BLOB_CHOICE_IT choice_it;
choice_it.set_to_list(scores + i);
float prev_score = -1;
int script_count = 0;
int prev_id = -1;
int prev_fontinfo_id = -1;
const char* prev_unichar = "";
const char* unichar = "";
for (choice_it.mark_cycle_pt(); !choice_it.cycled_list();
choice_it.forward()) {
BLOB_CHOICE* choice = choice_it.data();
int id = choice->script_id();
if (allowed_scripts_ != nullptr && !allowed_scripts_->empty()) {
// Check that the choice is in an allowed script.
int s = 0;
for (s = 0; s < allowed_scripts_->size(); ++s) {
if ((*allowed_scripts_)[s] == id) break;
}
if (s == allowed_scripts_->size()) continue; // Not found in list.
}
// Script already processed before.
if (done[id]) continue;
done[id] = true;
unichar = tess_->unicharset.id_to_unichar(choice->unichar_id());
// Save data from the first match
if (prev_score < 0) {
prev_score = -choice->certainty();
script_count = 1;
prev_id = id;
prev_unichar = unichar;
prev_fontinfo_id = choice->fontinfo_id();
} else if (-choice->certainty() < prev_score + kNonAmbiguousMargin) {
++script_count;
}
if (strlen(prev_unichar) == 1)
if (unichar[0] >= '0' && unichar[0] <= '9')
break;
// if script_count is >= 2, character is ambiguous, skip other matches
// since they are useless.
if (script_count >= 2)
break;
}
// Character is non ambiguous
if (script_count == 1) {
// Update the score of the winning script
osr_->scripts_na[i][prev_id] += 1.0;
// Workaround for Fraktur
if (prev_id == latin_id_) {
if (prev_fontinfo_id >= 0) {
const tesseract::FontInfo &fi =
tess_->get_fontinfo_table().get(prev_fontinfo_id);
//printf("Font: %s i:%i b:%i f:%i s:%i k:%i (%s)\n", fi.name,
// fi.is_italic(), fi.is_bold(), fi.is_fixed_pitch(),
// fi.is_serif(), fi.is_fraktur(),
// prev_unichar);
if (fi.is_fraktur()) {
osr_->scripts_na[i][prev_id] -= 1.0;
osr_->scripts_na[i][fraktur_id_] += 1.0;
}
}
}
// Update Japanese / Korean pseudo-scripts
if (prev_id == katakana_id_)
osr_->scripts_na[i][japanese_id_] += 1.0;
if (prev_id == hiragana_id_)
osr_->scripts_na[i][japanese_id_] += 1.0;
if (prev_id == hangul_id_)
osr_->scripts_na[i][korean_id_] += 1.0;
if (prev_id == han_id_) {
osr_->scripts_na[i][korean_id_] += kHanRatioInKorean;
osr_->scripts_na[i][japanese_id_] += kHanRatioInJapanese;
}
}
} // iterate over each orientation
}
bool ScriptDetector::must_stop(int orientation) {
osr_->update_best_script(orientation);
return osr_->best_result.sconfidence > 1;
}
// Helper method to convert an orientation index to its value in degrees.
// The value represents the amount of clockwise rotation in degrees that must be
// applied for the text to be upright (readable).
int OrientationIdToValue(const int& id) {
switch (id) {
case 0:
return 0;
case 1:
return 270;
case 2:
return 180;
case 3:
return 90;
default:
return -1;
}
}