classify/normfeat.cpp File Reference

#include "normfeat.h"
#include "intfx.h"
#include "featdefs.h"
#include "mfoutline.h"

Go to the source code of this file.

Functions
FLOAT32	ActualOutlineLength (FEATURE Feature)
FEATURE_SET	ExtractCharNormFeatures (const INT_FX_RESULT_STRUCT &fx_info)

---

Function Documentation

FLOAT32 ActualOutlineLength

(

FEATURE

Feature

)

Return the length of the outline in baseline normalized form.

Definition at line 32 of file normfeat.cpp.

                                             {
  return (Feature->Params[CharNormLength] * LENGTH_COMPRESSION);
}

FEATURE_SET ExtractCharNormFeatures

(

const INT_FX_RESULT_STRUCT &

fx_info

)

Return the character normalization feature for a blob.

The features returned are in a scale where the x-height has been normalized to live in the region y = [-0.25 .. 0.25]. Example ranges for English below are based on the Linux font collection on 2009-12-04:

• Params[CharNormY]
  • The y coordinate of the grapheme's centroid.
  • English: [-0.27, 0.71]

• Params[CharNormLength]
  • The length of the grapheme's outline (tiny segments discarded), divided by 10.0=LENGTH_COMPRESSION.
  • English: [0.16, 0.85]

• Params[CharNormRx]
  • The radius of gyration about the x axis, as measured from CharNormY.
  • English: [0.011, 0.34]

• Params[CharNormRy]
  • The radius of gyration about the y axis, as measured from the x center of the grapheme's bounding box.
  • English: [0.011, 0.31]

Definition at line 62 of file normfeat.cpp.

                                                                         {
  FEATURE_SET feature_set = NewFeatureSet(1);
  FEATURE feature = NewFeature(&CharNormDesc);

  feature->Params[CharNormY] =
      MF_SCALE_FACTOR * (fx_info.Ymean - kBlnBaselineOffset);
  feature->Params[CharNormLength] =
      MF_SCALE_FACTOR * fx_info.Length / LENGTH_COMPRESSION;
  feature->Params[CharNormRx] = MF_SCALE_FACTOR * fx_info.Rx;
  feature->Params[CharNormRy] = MF_SCALE_FACTOR * fx_info.Ry;

  AddFeature(feature_set, feature);

  return feature_set;
}                                /* ExtractCharNormFeatures */