tesseract  5.0.0
shapeclassifier.h
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1 // File: shapeclassifier.h
3 // Description: Base interface class for classifiers that return a
4 // shape index.
5 // Author: Ray Smith
6 //
7 // (C) Copyright 2011, Google Inc.
8 // Licensed under the Apache License, Version 2.0 (the "License");
9 // you may not use this file except in compliance with the License.
10 // You may obtain a copy of the License at
11 // http://www.apache.org/licenses/LICENSE-2.0
12 // Unless required by applicable law or agreed to in writing, software
13 // distributed under the License is distributed on an "AS IS" BASIS,
14 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 // See the License for the specific language governing permissions and
16 // limitations under the License.
17 //
19 
20 #ifndef TESSERACT_CLASSIFY_SHAPECLASSIFIER_H_
21 #define TESSERACT_CLASSIFY_SHAPECLASSIFIER_H_
22 
23 #include "image.h"
24 
25 #include <tesseract/unichar.h>
26 
27 #include <vector>
28 
29 struct Pix;
30 
31 namespace tesseract {
32 
33 class ScrollView;
34 class UNICHARSET;
35 
36 struct ShapeRating;
37 class ShapeTable;
38 class TrainingSample;
39 class TrainingSampleSet;
40 struct UnicharRating;
41 
42 // Interface base class for classifiers that produce ShapeRating results.
44 public:
45  virtual ~ShapeClassifier() = default;
46 
47  // Classifies the given [training] sample, writing to results.
48  // If page_pix is not nullptr, the overriding function may call
49  // sample.GetSamplePix(padding, page_pix) to get an image of the sample
50  // padded (with real image data) by the given padding to extract features
51  // from the image of the character. Other members of TrainingSample:
52  // features(), micro_features(), cn_feature(), geo_feature() may be used
53  // to get the appropriate tesseract features.
54  // If debug is non-zero, then various degrees of classifier dependent debug
55  // information is provided.
56  // If keep_this (a UNICHAR_ID) is >= 0, then the results should always
57  // contain keep_this, and (if possible) anything of intermediate confidence.
58  // (Used for answering "Why didn't it get that right?" questions.) It must
59  // be a UNICHAR_ID as the callers have no clue how to choose the best shape
60  // that may contain a desired answer.
61  // The return value is the number of classes saved in results.
62  // NOTE that overriding functions MUST clear and sort the results by
63  // descending rating unless the classifier is working with a team of such
64  // classifiers.
65  // NOTE: Neither overload of ClassifySample is pure, but at least one must
66  // be overridden by a classifier in order for it to do anything.
67  virtual int UnicharClassifySample(const TrainingSample &sample, Image page_pix, int debug,
68  UNICHAR_ID keep_this, std::vector<UnicharRating> *results);
69 
70 protected:
71  virtual int ClassifySample(const TrainingSample &sample, Image page_pix, int debug,
72  UNICHAR_ID keep_this, std::vector<ShapeRating> *results);
73 
74 public:
75  // Returns the shape that contains unichar_id that has the best result.
76  // If result is not nullptr, it is set with the shape_id and rating.
77  // Returns -1 if ClassifySample fails to provide any result containing
78  // unichar_id. BestShapeForUnichar does not need to be overridden if
79  // ClassifySample respects the keep_this rule.
80  virtual int BestShapeForUnichar(const TrainingSample &sample, Image page_pix,
81  UNICHAR_ID unichar_id, ShapeRating *result);
82 
83  // Provides access to the ShapeTable that this classifier works with.
84  virtual const ShapeTable *GetShapeTable() const = 0;
85  // Provides access to the UNICHARSET that this classifier works with.
86  // Must be overridden IFF GetShapeTable() returns nullptr.
87  virtual const UNICHARSET &GetUnicharset() const;
88 
89  // Visual debugger classifies the given sample, displays the results and
90  // solicits user input to display other classifications. Returns when
91  // the user has finished with debugging the sample.
92  // Probably doesn't need to be overridden if the subclass provides
93  // DisplayClassifyAs.
94  void DebugDisplay(const TrainingSample &sample, Image page_pix, UNICHAR_ID unichar_id);
95 
96  // Displays classification as the given unichar_id. Creates as many windows
97  // as it feels fit, using index as a guide for placement. Adds any created
98  // windows to the windows output and returns a new index that may be used
99  // by any subsequent classifiers. Caller waits for the user to view and
100  // then destroys the windows by clearing the vector.
101  virtual int DisplayClassifyAs(const TrainingSample &sample, Image page_pix, UNICHAR_ID unichar_id,
102  int index, std::vector<ScrollView *> &windows);
103 
104  // Prints debug information on the results. context is some introductory/title
105  // message.
106  virtual void UnicharPrintResults(const char *context,
107  const std::vector<UnicharRating> &results) const;
108  virtual void PrintResults(const char *context, const std::vector<ShapeRating> &results) const;
109 
110 protected:
111  // Removes any result that has all its unichars covered by a better choice,
112  // regardless of font.
113  void FilterDuplicateUnichars(std::vector<ShapeRating> *results) const;
114 };
115 
116 } // namespace tesseract.
117 
118 #endif // TESSERACT_CLASSIFY_SHAPECLASSIFIER_H_
int UNICHAR_ID
Definition: unichar.h:36
virtual ~ShapeClassifier()=default
virtual const ShapeTable * GetShapeTable() const =0
#define TESS_API
Definition: export.h:34