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comparison mupdf-source/thirdparty/tesseract/src/training/common/errorcounter.h @ 3:2c135c81b16c

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MERGE: upstream PyMuPDF 1.26.4 with MuPDF 1.26.7
author Franz Glasner <fzglas.hg@dom66.de>
date Mon, 15 Sep 2025 11:44:09 +0200
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1 // Copyright 2011 Google Inc. All Rights Reserved.
2 // Author: rays@google.com (Ray Smith)
3 //
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
7 // http://www.apache.org/licenses/LICENSE-2.0
8 // Unless required by applicable law or agreed to in writing, software
9 // distributed under the License is distributed on an "AS IS" BASIS,
10 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11 // See the License for the specific language governing permissions and
12 // limitations under the License.
13 //
14 ///////////////////////////////////////////////////////////////////////
15
16 #ifndef THIRD_PARTY_TESSERACT_CLASSIFY_ERRORCOUNTER_H_
17 #define THIRD_PARTY_TESSERACT_CLASSIFY_ERRORCOUNTER_H_
18
19 #include "matrix.h"
20 #include "statistc.h"
21
22 struct Pix;
23
24 namespace tesseract {
25
26 template <typename T>
27 class UnicityTable;
28 struct FontInfo;
29 class FontInfoTable;
30 class SampleIterator;
31 class ShapeClassifier;
32 class TrainingSample;
33 struct UnicharRating;
34
35 // Enumeration of the different types of error count.
36 // Error counts work as follows:
37 //
38 // Ground truth is a valid unichar-id / font-id pair:
39 // Number of classifier answers?
40 // 0 >0
41 // CT_REJECT unichar-id matches top shape?
42 // __________ yes! no
43 // CT_UNICHAR_TOP_OK CT_UNICHAR_TOP1_ERR
44 // Top shape-id has multiple unichars? 2nd shape unichar id matches?
45 // yes! no yes! no
46 // CT_OK_MULTI_UNICHAR | _____ CT_UNICHAR_TOP2_ERR
47 // Font attributes match? Any unichar-id matches?
48 // yes! no yes! no
49 // CT_FONT_ATTR_OK CT_FONT_ATTR_ERR ______ CT_UNICHAR_TOPN_ERR
50 // | __________________ _________________
51 // Top shape-id has multiple font attrs?
52 // yes! no
53 // CT_OK_MULTI_FONT
54 // _____________________________
55 //
56 // Note that multiple counts may be activated for a single sample!
57 //
58 // Ground truth is for a fragment/n-gram that is NOT in the unicharset.
59 // This is called junk and is expected to be rejected:
60 // Number of classifier answers?
61 // 0 >0
62 // CT_REJECTED_JUNK CT_ACCEPTED_JUNK
63 //
64 // Also, CT_NUM_RESULTS stores the mean number of results, and CT_RANK stores
65 // the mean rank of the correct result, counting from 0, and with an error
66 // receiving the number of answers as the correct rank.
67 //
68 // Keep in sync with the ReportString function.
69 enum CountTypes {
70 CT_UNICHAR_TOP_OK, // Top shape contains correct unichar id.
71 // The rank of the results in TOP1, TOP2, TOPN is determined by a gap of
72 // kRatingEpsilon from the first result in each group. The real top choice
73 // is measured using TOPTOP.
74 CT_UNICHAR_TOP1_ERR, // Top shape does not contain correct unichar id.
75 CT_UNICHAR_TOP2_ERR, // Top 2 shapes don't contain correct unichar id.
76 CT_UNICHAR_TOPN_ERR, // No output shape contains correct unichar id.
77 CT_UNICHAR_TOPTOP_ERR, // Very top choice not correct.
78 CT_OK_MULTI_UNICHAR, // Top shape id has correct unichar id, and others.
79 CT_OK_JOINED, // Top shape id is correct but marked joined.
80 CT_OK_BROKEN, // Top shape id is correct but marked broken.
81 CT_REJECT, // Classifier hates this.
82 CT_FONT_ATTR_ERR, // Top unichar OK, but font attributes incorrect.
83 CT_OK_MULTI_FONT, // CT_FONT_ATTR_OK but there are multiple font attrs.
84 CT_NUM_RESULTS, // Number of answers produced.
85 CT_RANK, // Rank of correct answer.
86 CT_REJECTED_JUNK, // Junk that was correctly rejected.
87 CT_ACCEPTED_JUNK, // Junk that was incorrectly classified otherwise.
88
89 CT_SIZE // Number of types for array sizing.
90 };
91
92 // Class to encapsulate all the functionality and sub-structures required
93 // to count errors for an isolated character classifier (ShapeClassifier).
94 class ErrorCounter {
95 public:
96 // Computes and returns the unweighted boosting_mode error rate of the given
97 // classifier. Can be used for testing, or inside an iterative training
98 // system, including one that uses boosting.
99 // report_levels:
100 // 0 = no output.
101 // 1 = bottom-line error rate.
102 // 2 = bottom-line error rate + time.
103 // 3 = font-level error rate + time.
104 // 4 = list of all errors + short classifier debug output on 16 errors.
105 // 5 = list of all errors + short classifier debug output on 25 errors.
106 // * The boosting_mode determines which error type is used for computing the
107 // scaled_error output, and setting the is_error flag in the samples.
108 // * The fontinfo_table is used to get string font names for the debug
109 // output, and also to count font attributes errors.
110 // * The page_images vector may contain a Pix* (which may be nullptr) for each
111 // page index assigned to the samples.
112 // * The it provides encapsulated iteration over some sample set.
113 // * The outputs unichar_error, scaled_error and totals_report are all
114 // optional.
115 // * If not nullptr, unichar error gets the top1 unichar error rate.
116 // * Scaled_error gets the error chosen by boosting_mode weighted by the
117 // weights on the samples.
118 // * Fonts_report gets a string summarizing the error rates for each font in
119 // both human-readable form and as a tab-separated list of error counts.
120 // The human-readable form is all before the first tab.
121 // * The return value is the un-weighted version of the scaled_error.
122 static double ComputeErrorRate(ShapeClassifier *classifier, int report_level,
123 CountTypes boosting_mode, const FontInfoTable &fontinfo_table,
124 const std::vector<Image > &page_images, SampleIterator *it,
125 double *unichar_error, double *scaled_error, std::string *fonts_report);
126 // Tests a pair of classifiers, debugging errors of the new against the old.
127 // See errorcounter.h for description of arguments.
128 // Iterates over the samples, calling the classifiers in normal/silent mode.
129 // If the new_classifier makes a boosting_mode error that the old_classifier
130 // does not, and the appropriate, it will then call the new_classifier again
131 // with a debug flag and a keep_this argument to find out what is going on.
132 static void DebugNewErrors(ShapeClassifier *new_classifier, ShapeClassifier *old_classifier,
133 CountTypes boosting_mode, const FontInfoTable &fontinfo_table,
134 const std::vector<Image > &page_images, SampleIterator *it);
135
136 private:
137 // Simple struct to hold an array of counts.
138 struct Counts {
139 Counts();
140 // Adds other into this for computing totals.
141 void operator+=(const Counts &other);
142
143 int n[CT_SIZE];
144 };
145
146 // Constructor is private. Only anticipated use of ErrorCounter is via
147 // the static ComputeErrorRate.
148 ErrorCounter(const UNICHARSET &unicharset, int fontsize);
149 ~ErrorCounter() = default;
150
151 // Accumulates the errors from the classifier results on a single sample.
152 // Returns true if debug is true and a CT_UNICHAR_TOPN_ERR error occurred.
153 // boosting_mode selects the type of error to be used for boosting and the
154 // is_error_ member of sample is set according to whether the required type
155 // of error occurred. The font_table provides access to font properties
156 // for error counting and shape_table is used to understand the relationship
157 // between unichar_ids and shape_ids in the results
158 bool AccumulateErrors(bool debug, CountTypes boosting_mode, const FontInfoTable &font_table,
159 const std::vector<UnicharRating> &results, TrainingSample *sample);
160
161 // Accumulates counts for junk. Counts only whether the junk was correctly
162 // rejected or not.
163 bool AccumulateJunk(bool debug, const std::vector<UnicharRating> &results,
164 TrainingSample *sample);
165
166 // Creates a report of the error rate. The report_level controls the detail
167 // that is reported to stderr via tprintf:
168 // 0 -> no output.
169 // >=1 -> bottom-line error rate.
170 // >=3 -> font-level error rate.
171 // boosting_mode determines the return value. It selects which (un-weighted)
172 // error rate to return.
173 // The fontinfo_table from MasterTrainer provides the names of fonts.
174 // The it determines the current subset of the training samples.
175 // If not nullptr, the top-choice unichar error rate is saved in
176 // unichar_error. If not nullptr, the report string is saved in fonts_report.
177 // (Ignoring report_level).
178 double ReportErrors(int report_level, CountTypes boosting_mode,
179 const FontInfoTable &fontinfo_table, const SampleIterator &it,
180 double *unichar_error, std::string *fonts_report);
181
182 // Sets the report string to a combined human and machine-readable report
183 // string of the error rates.
184 // Returns false if there is no data, leaving report unchanged, unless
185 // even_if_empty is true.
186 static bool ReportString(bool even_if_empty, const Counts &counts, std::string &report);
187
188 // Computes the error rates and returns in rates which is an array of size
189 // CT_SIZE. Returns false if there is no data, leaving rates unchanged.
190 static bool ComputeRates(const Counts &counts, double rates[CT_SIZE]);
191
192 // Total scaled error used by boosting algorithms.
193 double scaled_error_;
194 // Difference in result rating to be thought of as an "equal" choice.
195 double rating_epsilon_;
196 // Vector indexed by font_id from the samples of error accumulators.
197 std::vector<Counts> font_counts_;
198 // Counts of the results that map each unichar_id (from samples) to an
199 // incorrect shape_id.
200 GENERIC_2D_ARRAY<int> unichar_counts_;
201 // Count of the number of times each shape_id occurs, is correct, and multi-
202 // unichar.
203 std::vector<int> multi_unichar_counts_;
204 // Histogram of scores (as percent) for correct answers.
205 STATS ok_score_hist_;
206 // Histogram of scores (as percent) for incorrect answers.
207 STATS bad_score_hist_;
208 // Unicharset for printing character ids in results.
209 const UNICHARSET &unicharset_;
210 };
211
212 } // namespace tesseract.
213
214 #endif /* THIRD_PARTY_TESSERACT_CLASSIFY_ERRORCOUNTER_H_ */