tesseract  4.0.0-1-g2a2b
lm_consistency.cpp
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1 // File: lm_consistency.cpp
3 // Description: Struct for recording consistency of the paths representing
4 // OCR hypotheses.
5 // Author: Rika Antonova
6 // Created: Mon Jun 20 11:26:43 PST 2012
7 //
8 // (C) Copyright 2012, Google Inc.
9 // Licensed under the Apache License, Version 2.0 (the "License");
10 // you may not use this file except in compliance with the License.
11 // You may obtain a copy of the License at
12 // http://www.apache.org/licenses/LICENSE-2.0
13 // Unless required by applicable law or agreed to in writing, software
14 // distributed under the License is distributed on an "AS IS" BASIS,
15 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 // See the License for the specific language governing permissions and
17 // limitations under the License.
18 //
20 
21 #include "lm_consistency.h"
22 
23 #include "associate.h"
24 #include "dict.h"
25 #include "ratngs.h"
26 
27 namespace tesseract {
28 
30  const BLOB_CHOICE *b, bool is_punc) {
32  return; // It isn't going to get any better.
33 
34  // Compute xheight consistency.
35  bool parent_null = xht_sp < 0;
36  int parent_sp = xht_sp;
37  // Debug strings.
40  } else if (b->yshift() < -LMConsistencyInfo::kShiftThresh) {
42  } else {
44  }
45  xht_count[xht_sp]++;
46  if (is_punc) xht_count_punc[xht_sp]++;
47  if (!parent_null) {
48  xpos_entropy += abs(parent_sp - xht_sp);
49  }
50  // TODO(eger): Figure out a better way to account for small caps.
51  // For the first character not y-shifted, we only care if it is too small.
52  // Too large is common in drop caps and small caps.
53  // int16_t small_xht = b->min_xheight();
54  // if (parent_vse == nullptr && sp == LanguageModelConsistencyInfo::kNORM) {
55  // small_xht = 0;
56  // }
58  &(xht_lo[xht_sp]), &(xht_hi[xht_sp]));
59 
60 
61  // Compute xheight inconsistency kinds.
62  if (parent_null) {
63  if (xht_count[kNORM] == 1) {
65  } else {
67  }
68  return;
69  }
70 
71  // When we intersect the ranges of xheights in pixels for all characters in
72  // each position (subscript, normal, superscript),
73  // How much range must be left? 0? [exactly one pixel height for xheight] 1?
74  // TODO(eger): Extend this code to take a prior for the rest of the line.
75  const int kMinIntersectedXHeightRange = 0;
76  for (int i = 0; i < kNumPos; i++) {
77  if (xht_lo[i] > xht_hi[i] - kMinIntersectedXHeightRange) {
79  return;
80  }
81  }
82 
83  // Reject as improbable anything where there's much punctuation in subscript
84  // or superscript regions.
85  if (xht_count_punc[kSUB] > xht_count[kSUB] * 0.4 ||
86  xht_count_punc[kSUP] > xht_count[kSUP] * 0.4) {
88  return;
89  }
90 
91  // Now check that the subscript and superscript aren't too small relative to
92  // the mainline.
93  double mainline_xht = static_cast<double>(xht_lo[kNORM]);
94  double kMinSizeRatio = 0.4;
95  if (mainline_xht > 0.0 &&
96  (static_cast<double>(xht_hi[kSUB]) / mainline_xht < kMinSizeRatio ||
97  static_cast<double>(xht_hi[kSUP]) / mainline_xht < kMinSizeRatio)) {
99  return;
100  }
101  // TODO(eger): Check into inconsistency of super/subscript y offsets.
102  if (xpos_entropy > kMaxEntropy) {
104  return;
105  }
106  if (xht_count[kSUB] == 0 && xht_count[kSUP] == 0) {
108  return;
109  }
111 }
112 
113 } // namespace tesseract
static const int kMaxEntropy
int16_t xht_count_punc[kNumPos]
float yshift() const
Definition: ratngs.h:130
static const int kShiftThresh
float min_xheight() const
Definition: ratngs.h:124
float max_xheight() const
Definition: ratngs.h:127
void IntersectRange(const T &lower1, const T &upper1, T *lower2, T *upper2)
Definition: helpers.h:142
XHeightConsistencyEnum xht_decision
void ComputeXheightConsistency(const BLOB_CHOICE *b, bool is_punc)