Added a backup adaptive classifier to take over from primary when it fills on a large document

Author: theraysmith

api/baseapi.cpp

@@ -2380,7 +2380,8 @@ void TessBaseAPI::AdaptToCharacter(const char *unichar_repr,
   threshold = tesseract_->matcher_good_threshold;
 
   if (blob->outlines)
-    tesseract_->AdaptToChar(blob, id, kUnknownFontinfoId, threshold);
+    tesseract_->AdaptToChar(blob, id, kUnknownFontinfoId, threshold,
+                            tesseract_->AdaptedTemplates);
   delete blob;
 }
 

ccmain/control.cpp

@@ -306,17 +306,22 @@ bool Tesseract::recog_all_words(PAGE_RES* page_res,
     page_res_it.restart_page();
     // ****************** Pass 1 *******************
 
-    // Clear adaptive classifier at the beginning of the page if it is full.
-    // This is done only at the beginning of the page to ensure that the
-    // classifier is not reset at an arbitrary point while processing the page,
-    // which would cripple Passes 2+ if the reset happens towards the end of
-    // Pass 1 on a page with very difficult text.
-    // TODO(daria): preemptively clear the classifier if it is almost full.
-    if (AdaptiveClassifierIsFull()) ResetAdaptiveClassifierInternal();
+    // If the adaptive classifier is full switch to one we prepared earlier,
+    // ie on the previous page. If the current adaptive classifier is non-empty,
+    // prepare a backup starting at this page, in case it fills up. Do all this
+    // independently for each language.
+    if (AdaptiveClassifierIsFull()) {
+      SwitchAdaptiveClassifier();
+    } else if (!AdaptiveClassifierIsEmpty()) {
+      StartBackupAdaptiveClassifier();
+    }
     // Now check the sub-langs as well.
     for (int i = 0; i < sub_langs_.size(); ++i) {
-      if (sub_langs_[i]->AdaptiveClassifierIsFull())
-        sub_langs_[i]->ResetAdaptiveClassifierInternal();
+      if (sub_langs_[i]->AdaptiveClassifierIsFull()) {
+        sub_langs_[i]->SwitchAdaptiveClassifier();
+      } else if (!sub_langs_[i]->AdaptiveClassifierIsEmpty()) {
+        sub_langs_[i]->StartBackupAdaptiveClassifier();
+      }
     }
     // Set up all words ready for recognition, so that if parallelism is on
     // all the input and output classes are ready to run the classifier.

classify/adaptmatch.cpp

@@ -24,36 +24,36 @@
 #endif
 
 #include <ctype.h>
-#include "shapeclassifier.h"
 #include "ambigs.h"
 #include "blobclass.h"
 #include "blobs.h"
-#include "helpers.h"
-#include "normfeat.h"
-#include "mfoutline.h"
-#include "picofeat.h"
-#include "float2int.h"
-#include "outfeat.h"
+#include "callcpp.h"
+#include "classify.h"
+#include "const.h"
+#include "dict.h"
+#include "efio.h"
 #include "emalloc.h"
+#include "featdefs.h"
+#include "float2int.h"
+#include "genericvector.h"
+#include "globals.h"
+#include "helpers.h"
 #include "intfx.h"
-#include "efio.h"
-#include "normmatch.h"
-#include "ndminx.h"
 #include "intproto.h"
-#include "const.h"
-#include "globals.h"
-#include "werd.h"
-#include "callcpp.h"
+#include "mfoutline.h"
+#include "ndminx.h"
+#include "normfeat.h"
+#include "normmatch.h"
+#include "outfeat.h"
 #include "pageres.h"
 #include "params.h"
-#include "classify.h"
+#include "picofeat.h"
+#include "shapeclassifier.h"
 #include "shapetable.h"
 #include "tessclassifier.h"
 #include "trainingsample.h"
 #include "unicharset.h"
-#include "dict.h"
-#include "featdefs.h"
-#include "genericvector.h"
+#include "werd.h"
 
 #include <stdio.h>
 #include <string.h>
@@ -420,7 +420,13 @@ void Classify::LearnPieces(const char* fontname, int start, int length,
               unicharset.id_to_unichar(class_id), threshold, font_id);
     // If filename is not NULL we are doing recognition
     // (as opposed to training), so we must have already set word fonts.
-    AdaptToChar(rotated_blob, class_id, font_id, threshold);
+    AdaptToChar(rotated_blob, class_id, font_id, threshold, AdaptedTemplates);
+    if (BackupAdaptedTemplates != NULL) {
+      // Adapt the backup templates too. They will be used if the primary gets
+      // too full.
+      AdaptToChar(rotated_blob, class_id, font_id, threshold,
+                  BackupAdaptedTemplates);
+    }
   } else if (classify_debug_level >= 1) {
     tprintf("Can't adapt to %s not in unicharset\n", correct_text);
   }
@@ -470,6 +476,10 @@ void Classify::EndAdaptiveClassifier() {
     free_adapted_templates(AdaptedTemplates);
     AdaptedTemplates = NULL;
   }
+  if (BackupAdaptedTemplates != NULL) {
+    free_adapted_templates(BackupAdaptedTemplates);
+    BackupAdaptedTemplates = NULL;
+  }
 
   if (PreTrainedTemplates != NULL) {
     free_int_templates(PreTrainedTemplates);
@@ -607,10 +617,35 @@ void Classify::ResetAdaptiveClassifierInternal() {
   }
   free_adapted_templates(AdaptedTemplates);
   AdaptedTemplates = NewAdaptedTemplates(true);
+  if (BackupAdaptedTemplates != NULL)
+    free_adapted_templates(BackupAdaptedTemplates);
+  BackupAdaptedTemplates = NULL;
   NumAdaptationsFailed = 0;
 }
 
+// If there are backup adapted templates, switches to those, otherwise resets
+// the main adaptive classifier (because it is full.)
+void Classify::SwitchAdaptiveClassifier() {
+  if (BackupAdaptedTemplates == NULL) {
+    ResetAdaptiveClassifierInternal();
+    return;
+  }
+  if (classify_learning_debug_level > 0) {
+    tprintf("Switch to backup adaptive classifier (NumAdaptationsFailed=%d)\n",
+            NumAdaptationsFailed);
+  }
+  free_adapted_templates(AdaptedTemplates);
+  AdaptedTemplates = BackupAdaptedTemplates;
+  BackupAdaptedTemplates = NULL;
+  NumAdaptationsFailed = 0;
+}
 
+// Resets the backup adaptive classifier to empty.
+void Classify::StartBackupAdaptiveClassifier() {
+  if (BackupAdaptedTemplates != NULL)
+    free_adapted_templates(BackupAdaptedTemplates);
+  BackupAdaptedTemplates = NewAdaptedTemplates(true);
+}
 
 /*---------------------------------------------------------------------------*/
 /**
@@ -839,20 +874,19 @@ bool Classify::AdaptableWord(WERD_RES* word) {
  * @param ClassId class to add blob to
  * @param FontinfoId font information from pre-trained templates
  * @param Threshold minimum match rating to existing template
+ * @param adaptive_templates current set of adapted templates
  *
  * Globals:
- * - AdaptedTemplates current set of adapted templates
  * - AllProtosOn dummy mask to match against all protos
  * - AllConfigsOn dummy mask to match against all configs
  *
  * @return none
  * @note Exceptions: none
  * @note History: Thu Mar 14 09:36:03 1991, DSJ, Created.
  */
-void Classify::AdaptToChar(TBLOB *Blob,
-                           CLASS_ID ClassId,
-                           int FontinfoId,
-                           FLOAT32 Threshold) {
+void Classify::AdaptToChar(TBLOB* Blob, CLASS_ID ClassId, int FontinfoId,
+                           FLOAT32 Threshold,
+                           ADAPT_TEMPLATES adaptive_templates) {
   int NumFeatures;
   INT_FEATURE_ARRAY IntFeatures;
   UnicharRating int_result;
@@ -866,12 +900,12 @@ void Classify::AdaptToChar(TBLOB *Blob,
     return;
 
   int_result.unichar_id = ClassId;
-  Class = AdaptedTemplates->Class[ClassId];
+  Class = adaptive_templates->Class[ClassId];
   assert(Class != NULL);
   if (IsEmptyAdaptedClass(Class)) {
-    InitAdaptedClass(Blob, ClassId, FontinfoId, Class, AdaptedTemplates);
+    InitAdaptedClass(Blob, ClassId, FontinfoId, Class, adaptive_templates);
   } else {
-    IClass = ClassForClassId(AdaptedTemplates->Templates, ClassId);
+    IClass = ClassForClassId(adaptive_templates->Templates, ClassId);
 
     NumFeatures = GetAdaptiveFeatures(Blob, IntFeatures, &FloatFeatures);
     if (NumFeatures <= 0)
@@ -913,7 +947,7 @@ void Classify::AdaptToChar(TBLOB *Blob,
                 int_result.config, TempConfig->NumTimesSeen);
 
       if (TempConfigReliable(ClassId, TempConfig)) {
-        MakePermanent(AdaptedTemplates, ClassId, int_result.config, Blob);
+        MakePermanent(adaptive_templates, ClassId, int_result.config, Blob);
         UpdateAmbigsGroup(ClassId, Blob);
       }
     } else {
@@ -923,15 +957,12 @@ void Classify::AdaptToChar(TBLOB *Blob,
         if (classify_learning_debug_level > 2)
           DisplayAdaptedChar(Blob, IClass);
       }
-      NewTempConfigId = MakeNewTemporaryConfig(AdaptedTemplates,
-                                               ClassId,
-                                               FontinfoId,
-                                               NumFeatures,
-                                               IntFeatures,
-                                               FloatFeatures);
+      NewTempConfigId =
+          MakeNewTemporaryConfig(adaptive_templates, ClassId, FontinfoId,
+                                 NumFeatures, IntFeatures, FloatFeatures);
       if (NewTempConfigId >= 0 &&
           TempConfigReliable(ClassId, TempConfigFor(Class, NewTempConfigId))) {
-        MakePermanent(AdaptedTemplates, ClassId, NewTempConfigId, Blob);
+        MakePermanent(adaptive_templates, ClassId, NewTempConfigId, Blob);
         UpdateAmbigsGroup(ClassId, Blob);
       }
 
@@ -1547,7 +1578,7 @@ void Classify::DebugAdaptiveClassifier(TBLOB *blob,
  * Globals:
  * - PreTrainedTemplates built-in training templates
  * - AdaptedTemplates templates adapted for this page
- * - matcher_great_threshold rating limit for a great match
+ * - matcher_reliable_adaptive_result rating limit for a great match
  *
  * @note Exceptions: none
  * @note History: Tue Mar 12 08:50:11 1991, DSJ, Created.
@@ -1569,7 +1600,8 @@ void Classify::DoAdaptiveMatch(TBLOB *Blob, ADAPT_RESULTS *Results) {
     Ambiguities = BaselineClassifier(Blob, bl_features, fx_info,
                                      AdaptedTemplates, Results);
     if ((!Results->match.empty() &&
-         MarginalMatch(Results->best_rating, matcher_great_threshold) &&
+         MarginalMatch(Results->best_rating,
+                       matcher_reliable_adaptive_result) &&
          !tess_bn_matching) ||
         Results->match.empty()) {
       CharNormClassifier(Blob, *sample, Results);

classify/classify.cpp

@@ -171,6 +171,7 @@ Classify::Classify()
   fontset_table_.set_clear_callback(
       NewPermanentTessCallback(FontSetDeleteCallback));
   AdaptedTemplates = NULL;
+  BackupAdaptedTemplates = NULL;
   PreTrainedTemplates = NULL;
   AllProtosOn = NULL;
   AllConfigsOn = NULL;

classify/classify.h

@@ -253,10 +253,8 @@ class Classify : public CCStruct {
                              GenericVector<UnicharRating>* results);
   UNICHAR_ID *GetAmbiguities(TBLOB *Blob, CLASS_ID CorrectClass);
   void DoAdaptiveMatch(TBLOB *Blob, ADAPT_RESULTS *Results);
-  void AdaptToChar(TBLOB *Blob,
-                   CLASS_ID ClassId,
-                   int FontinfoId,
-                   FLOAT32 Threshold);
+  void AdaptToChar(TBLOB* Blob, CLASS_ID ClassId, int FontinfoId,
+                   FLOAT32 Threshold, ADAPT_TEMPLATES adaptive_templates);
   void DisplayAdaptedChar(TBLOB* blob, INT_CLASS_STRUCT* int_class);
   bool AdaptableWord(WERD_RES* word);
   void EndAdaptiveClassifier();
@@ -265,6 +263,8 @@ class Classify : public CCStruct {
   void AdaptiveClassifier(TBLOB *Blob, BLOB_CHOICE_LIST *Choices);
   void ClassifyAsNoise(ADAPT_RESULTS *Results);
   void ResetAdaptiveClassifierInternal();
+  void SwitchAdaptiveClassifier();
+  void StartBackupAdaptiveClassifier();
 
   int GetCharNormFeature(const INT_FX_RESULT_STRUCT& fx_info,
                          INT_TEMPLATES templates,
@@ -281,7 +281,10 @@ class Classify : public CCStruct {
   bool TempConfigReliable(CLASS_ID class_id, const TEMP_CONFIG &config);
   void UpdateAmbigsGroup(CLASS_ID class_id, TBLOB *Blob);
 
-  bool AdaptiveClassifierIsFull() { return NumAdaptationsFailed > 0; }
+  bool AdaptiveClassifierIsFull() const { return NumAdaptationsFailed > 0; }
+  bool AdaptiveClassifierIsEmpty() const {
+    return AdaptedTemplates->NumPermClasses == 0;
+  }
   bool LooksLikeGarbage(TBLOB *blob);
   void RefreshDebugWindow(ScrollView **win, const char *msg,
                           int y_offset, const TBOX &wbox);
@@ -415,7 +418,7 @@ class Classify : public CCStruct {
   INT_VAR_H(matcher_debug_flags, 0, "Matcher Debug Flags");
   INT_VAR_H(classify_learning_debug_level, 0, "Learning Debug Level: ");
   double_VAR_H(matcher_good_threshold, 0.125, "Good Match (0-1)");
-  double_VAR_H(matcher_great_threshold, 0.0, "Great Match (0-1)");
+  double_VAR_H(matcher_reliable_adaptive_result, 0.0, "Great Match (0-1)");
   double_VAR_H(matcher_perfect_threshold, 0.02, "Perfect Match (0-1)");
   double_VAR_H(matcher_bad_match_pad, 0.15, "Bad Match Pad (0-1)");
   double_VAR_H(matcher_rating_margin, 0.1, "New template margin (0-1)");
@@ -468,6 +471,10 @@ class Classify : public CCStruct {
   // Use class variables to hold onto built-in templates and adapted templates.
   INT_TEMPLATES PreTrainedTemplates;
   ADAPT_TEMPLATES AdaptedTemplates;
+  // The backup adapted templates are created from the previous page (only)
+  // so they are always ready and reasonably well trained if the primary
+  // adapted templates become full.
+  ADAPT_TEMPLATES BackupAdaptedTemplates;
 
   // Create dummy proto and config masks for use with the built-in templates.
   BIT_VECTOR AllProtosOn;