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Fix assertion caused by access to default TBOX
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Instead of adding an empty TBOX at the end of the box list,
that corner case is now handled by passing a nullptr (like
it was already done for the first box in the list).

This avoids the calls of BoxMissMetric with a TBOX
which raises an assertion there (b == 0).

Signed-off-by: Stefan Weil <sw@weilnetz.de>
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stweil committed Aug 22, 2018
1 parent 97f6864 commit b08966a
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Showing 2 changed files with 46 additions and 43 deletions.
81 changes: 42 additions & 39 deletions src/ccmain/applybox.cpp
View file
Expand Up @@ -122,29 +122,24 @@ PAGE_RES* Tesseract::ApplyBoxes(const STRING& fname,

const int box_count = boxes.size();
int box_failures = 0;
// Add an empty everything to the end.
boxes.push_back(TBOX());
texts.push_back(STRING());
full_texts.push_back(STRING());

// In word mode, we use the boxes to make a word for each box, but
// in blob mode we use the existing words and maximally chop them first.
PAGE_RES* page_res = find_segmentation ?
nullptr : SetupApplyBoxes(boxes, block_list);
clear_any_old_text(block_list);

for (int i = 0; i < boxes.size() - 1; i++) {
for (int i = 0; i < box_count; i++) {
bool foundit = false;
if (page_res != nullptr) {
if (i == 0) {
foundit = ResegmentCharBox(page_res, nullptr, boxes[i], boxes[i + 1],
full_texts[i].string());
} else {
foundit = ResegmentCharBox(page_res, &boxes[i-1], boxes[i],
boxes[i + 1], full_texts[i].string());
}
foundit = ResegmentCharBox(page_res,
(i == 0) ? nullptr : &boxes[i - 1],
boxes[i],
(i == box_count - 1) ? nullptr : &boxes[i + 1],
full_texts[i].string());
} else {
foundit = ResegmentWordBox(block_list, boxes[i], boxes[i + 1],
foundit = ResegmentWordBox(block_list, boxes[i],
(i == box_count - 1) ? nullptr : &boxes[i + 1],
texts[i].string());
}
if (!foundit) {
Expand Down Expand Up @@ -339,8 +334,8 @@ static double BoxMissMetric(const TBOX& box1, const TBOX& box2) {
///
/// This means that occasionally, blobs may be incorrectly segmented if the
/// chopper fails to find a suitable chop point.
bool Tesseract::ResegmentCharBox(PAGE_RES* page_res, const TBOX *prev_box,
const TBOX& box, const TBOX& next_box,
bool Tesseract::ResegmentCharBox(PAGE_RES* page_res, const TBOX* prev_box,
const TBOX& box, const TBOX* next_box,
const char* correct_text) {
if (applybox_debug > 1) {
tprintf("\nAPPLY_BOX: in ResegmentCharBox() for %s\n", correct_text);
Expand All @@ -365,24 +360,26 @@ bool Tesseract::ResegmentCharBox(PAGE_RES* page_res, const TBOX *prev_box,
break;
if (word_res->correct_text[i + blob_count].length() > 0)
break; // Blob is claimed already.
const double current_box_miss_metric = BoxMissMetric(blob_box, box);
const double next_box_miss_metric = BoxMissMetric(blob_box, next_box);
if (applybox_debug > 2) {
tprintf("Checking blob:");
blob_box.print();
tprintf("Current miss metric = %g, next = %g\n",
current_box_miss_metric, next_box_miss_metric);
if (next_box != nullptr) {
const double current_box_miss_metric = BoxMissMetric(blob_box, box);
const double next_box_miss_metric = BoxMissMetric(blob_box, *next_box);
if (applybox_debug > 2) {
tprintf("Checking blob:");
blob_box.print();
tprintf("Current miss metric = %g, next = %g\n",
current_box_miss_metric, next_box_miss_metric);
}
if (current_box_miss_metric > next_box_miss_metric)
break; // Blob is a better match for next box.
}
if (current_box_miss_metric > next_box_miss_metric)
break; // Blob is a better match for next box.
char_box += blob_box;
}
if (blob_count > 0) {
if (applybox_debug > 1) {
tprintf("Index [%d, %d) seem good.\n", i, i + blob_count);
}
if (!char_box.almost_equal(box, 3) &&
(box.x_gap(next_box) < -3 ||
((next_box != nullptr && box.x_gap(*next_box) < -3)||
(prev_box != nullptr && prev_box->x_gap(box) < -3))) {
return false;
}
Expand All @@ -398,8 +395,10 @@ bool Tesseract::ResegmentCharBox(PAGE_RES* page_res, const TBOX *prev_box,
word_res->box_word->BlobBox(i).print();
tprintf("Matches box:");
box.print();
tprintf("With next box:");
next_box.print();
if (next_box != nullptr) {
tprintf("With next box:");
next_box->print();
}
}
// Eliminated best_state and correct_text entries for the consumed
// blobs.
Expand Down Expand Up @@ -438,7 +437,7 @@ bool Tesseract::ResegmentCharBox(PAGE_RES* page_res, const TBOX *prev_box,
/// @return false if the box was in error, which can only be caused by
/// failing to find an overlapping blob for a box.
bool Tesseract::ResegmentWordBox(BLOCK_LIST *block_list,
const TBOX& box, const TBOX& next_box,
const TBOX& box, const TBOX* next_box,
const char* correct_text) {
if (applybox_debug > 1) {
tprintf("\nAPPLY_BOX: in ResegmentWordBox() for %s\n", correct_text);
Expand Down Expand Up @@ -472,23 +471,27 @@ bool Tesseract::ResegmentWordBox(BLOCK_LIST *block_list,
TBOX blob_box = blob->bounding_box();
if (!blob_box.major_overlap(box))
continue;
const double current_box_miss_metric = BoxMissMetric(blob_box, box);
const double next_box_miss_metric = BoxMissMetric(blob_box, next_box);
if (applybox_debug > 2) {
tprintf("Checking blob:");
blob_box.print();
tprintf("Current miss metric = %g, next = %g\n",
current_box_miss_metric, next_box_miss_metric);
if (next_box != nullptr) {
const double current_box_miss_metric = BoxMissMetric(blob_box, box);
const double next_box_miss_metric = BoxMissMetric(blob_box, *next_box);
if (applybox_debug > 2) {
tprintf("Checking blob:");
blob_box.print();
tprintf("Current miss metric = %g, next = %g\n",
current_box_miss_metric, next_box_miss_metric);
}
if (current_box_miss_metric > next_box_miss_metric)
continue; // Blob is a better match for next box.
}
if (current_box_miss_metric > next_box_miss_metric)
continue; // Blob is a better match for next box.
if (applybox_debug > 2) {
tprintf("Blob match: blob:");
blob_box.print();
tprintf("Matches box:");
box.print();
tprintf("With next box:");
next_box.print();
if (next_box != nullptr) {
tprintf("With next box:");
next_box->print();
}
}
if (new_word == nullptr) {
// Make a new word with a single blob.
Expand Down
8 changes: 4 additions & 4 deletions src/ccmain/tesseractclass.h
View file
Expand Up @@ -744,17 +744,17 @@ class Tesseract : public Wordrec {
// failing to find an appropriate blob for a box.
// This means that occasionally, blobs may be incorrectly segmented if the
// chopper fails to find a suitable chop point.
bool ResegmentCharBox(PAGE_RES* page_res, const TBOX *prev_box,
const TBOX& box, const TBOX& next_box,
bool ResegmentCharBox(PAGE_RES* page_res, const TBOX* prev_box,
const TBOX& box, const TBOX* next_box,
const char* correct_text);
// Consume all source blobs that strongly overlap the given box,
// putting them into a new word, with the correct_text label.
// Fights over which box owns which blobs are settled by
// applying the blobs to box or next_box with the least non-overlap.
// Returns false if the box was in error, which can only be caused by
// failing to find an overlapping blob for a box.
bool ResegmentWordBox(BLOCK_LIST *block_list,
const TBOX& box, const TBOX& next_box,
bool ResegmentWordBox(BLOCK_LIST* block_list,
const TBOX& box, const TBOX* next_box,
const char* correct_text);
// Resegments the words by running the classifier in an attempt to find the
// correct segmentation that produces the required string.
Expand Down

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