outfeat.cpp

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/******************************************************************************
 ** Filename:    outfeat.c
 ** Purpose:     Definition of outline-features.
 ** Author:      Dan Johnson
 **
 ** (c) Copyright Hewlett-Packard Company, 1988.
 ** Licensed under the Apache License, Version 2.0 (the "License");
 ** you may not use this file except in compliance with the License.
 ** You may obtain a copy of the License at
 ** http://www.apache.org/licenses/LICENSE-2.0
 ** Unless required by applicable law or agreed to in writing, software
 ** distributed under the License is distributed on an "AS IS" BASIS,
 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 ** See the License for the specific language governing permissions and
 ** limitations under the License.
 ******************************************************************************/
 
#include "outfeat.h"
 
#include "classify.h"
#include "featdefs.h"
#include "mfoutline.h"
#include "ocrfeatures.h"
 
#include <cstdio>
 
namespace tesseract {
 
/*----------------------------------------------------------------------------
              Public Code
----------------------------------------------------------------------------*/
 
FEATURE_SET Classify::ExtractOutlineFeatures(TBLOB *Blob) {
  auto FeatureSet = new FEATURE_SET_STRUCT(MAX_OUTLINE_FEATURES);
  if (Blob == nullptr) {
    return (FeatureSet);
  }
 
  auto Outlines = ConvertBlob(Blob);
 
  float XScale, YScale;
  NormalizeOutlines(Outlines, &XScale, &YScale);
  auto RemainingOutlines = Outlines;
  iterate(RemainingOutlines) {
    auto Outline = static_cast<MFOUTLINE>(RemainingOutlines->first_node());
    ConvertToOutlineFeatures(Outline, FeatureSet);
  }
  if (classify_norm_method == baseline) {
    NormalizeOutlineX(FeatureSet);
  }
  FreeOutlines(Outlines);
  return (FeatureSet);
} /* ExtractOutlineFeatures */
 
/*----------------------------------------------------------------------------
              Private Code
----------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
void AddOutlineFeatureToSet(FPOINT *Start, FPOINT *End, FEATURE_SET FeatureSet) {
  auto Feature = new FEATURE_STRUCT(&OutlineFeatDesc);
  Feature->Params[OutlineFeatDir] = NormalizedAngleFrom(Start, End, 1.0);
  Feature->Params[OutlineFeatX] = AverageOf(Start->x, End->x);
  Feature->Params[OutlineFeatY] = AverageOf(Start->y, End->y);
  Feature->Params[OutlineFeatLength] = DistanceBetween(*Start, *End);
  AddFeature(FeatureSet, Feature);
 
} /* AddOutlineFeatureToSet */
 
/*---------------------------------------------------------------------------*/
void ConvertToOutlineFeatures(MFOUTLINE Outline, FEATURE_SET FeatureSet) {
  MFOUTLINE Next;
  MFOUTLINE First;
  FPOINT FeatureStart;
  FPOINT FeatureEnd;
 
  if (DegenerateOutline(Outline)) {
    return;
  }
 
  First = Outline;
  Next = First;
  do {
    FeatureStart = PointAt(Next)->Point;
    Next = NextPointAfter(Next);
 
    /* note that an edge is hidden if the ending point of the edge is
   marked as hidden.  This situation happens because the order of
   the outlines is reversed when they are converted from the old
   format.  In the old format, a hidden edge is marked by the
   starting point for that edge. */
    if (!PointAt(Next)->Hidden) {
      FeatureEnd = PointAt(Next)->Point;
      AddOutlineFeatureToSet(&FeatureStart, &FeatureEnd, FeatureSet);
    }
  } while (Next != First);
} /* ConvertToOutlineFeatures */
 
/*---------------------------------------------------------------------------*/
void NormalizeOutlineX(FEATURE_SET FeatureSet) {
  int i;
  FEATURE Feature;
  float Length;
  float TotalX = 0.0;
  float TotalWeight = 0.0;
  float Origin;
 
  if (FeatureSet->NumFeatures <= 0) {
    return;
  }
 
  for (i = 0; i < FeatureSet->NumFeatures; i++) {
    Feature = FeatureSet->Features[i];
    Length = Feature->Params[OutlineFeatLength];
    TotalX += Feature->Params[OutlineFeatX] * Length;
    TotalWeight += Length;
  }
  Origin = TotalX / TotalWeight;
 
  for (i = 0; i < FeatureSet->NumFeatures; i++) {
    Feature = FeatureSet->Features[i];
    Feature->Params[OutlineFeatX] -= Origin;
  }
} /* NormalizeOutlineX */
 
} // namespace tesseract