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tesseract/classify/normmatch.cpp

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/******************************************************************************
** Filename: normmatch.c
** Purpose: Simple matcher based on character normalization features.
** Author: Dan Johnson
** History: Wed Dec 19 16:18:06 1990, DSJ, Created.
**
** (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 Files and Type Defines
----------------------------------------------------------------------------**/
#include "normmatch.h"
#include <stdio.h>
#include <math.h>
#include "classify.h"
#include "clusttool.h"
#include "const.h"
#include "efio.h"
#include "emalloc.h"
#include "globals.h"
#include "helpers.h"
#include "normfeat.h"
#include "scanutils.h"
#include "unicharset.h"
#include "params.h"
struct NORM_PROTOS
{
int NumParams;
PARAM_DESC *ParamDesc;
LIST* Protos;
int NumProtos;
};
/**----------------------------------------------------------------------------
Private Function Prototypes
----------------------------------------------------------------------------**/
double NormEvidenceOf(register double NormAdj);
void PrintNormMatch(FILE *File,
int NumParams,
PROTOTYPE *Proto,
FEATURE Feature);
NORM_PROTOS *ReadNormProtos(FILE *File);
/**----------------------------------------------------------------------------
Variables
----------------------------------------------------------------------------**/
/* control knobs used to control the normalization adjustment process */
double_VAR(classify_norm_adj_midpoint, 32.0, "Norm adjust midpoint ...");
double_VAR(classify_norm_adj_curl, 2.0, "Norm adjust curl ...");
// Weight of width variance against height and vertical position.
const double kWidthErrorWeighting = 0.125;
/**----------------------------------------------------------------------------
Public Code
----------------------------------------------------------------------------**/
/*---------------------------------------------------------------------------*/
namespace tesseract {
FLOAT32 Classify::ComputeNormMatch(CLASS_ID ClassId,
const FEATURE_STRUCT& feature,
BOOL8 DebugMatch) {
/*
** Parameters:
** ClassId id of class to match against
** Feature character normalization feature
** DebugMatch controls dump of debug info
** Globals:
** NormProtos character normalization prototypes
** Operation: This routine compares Features against each character
** normalization proto for ClassId and returns the match
** rating of the best match.
** Return: Best match rating for Feature against protos of ClassId.
** Exceptions: none
** History: Wed Dec 19 16:56:12 1990, DSJ, Created.
*/
LIST Protos;
FLOAT32 BestMatch;
FLOAT32 Match;
FLOAT32 Delta;
PROTOTYPE *Proto;
int ProtoId;
/* handle requests for classification as noise */
if (ClassId == NO_CLASS) {
/* kludge - clean up constants and make into control knobs later */
Match = (feature.Params[CharNormLength] *
feature.Params[CharNormLength] * 500.0 +
feature.Params[CharNormRx] *
feature.Params[CharNormRx] * 8000.0 +
feature.Params[CharNormRy] *
feature.Params[CharNormRy] * 8000.0);
return (1.0 - NormEvidenceOf (Match));
}
BestMatch = MAX_FLOAT32;
Protos = NormProtos->Protos[ClassId];
if (DebugMatch) {
tprintf("\nChar norm for class %s\n", unicharset.id_to_unichar(ClassId));
}
ProtoId = 0;
iterate(Protos) {
Proto = (PROTOTYPE *) first_node (Protos);
Delta = feature.Params[CharNormY] - Proto->Mean[CharNormY];
Match = Delta * Delta * Proto->Weight.Elliptical[CharNormY];
if (DebugMatch) {
tprintf("YMiddle: Proto=%g, Delta=%g, Var=%g, Dist=%g\n",
Proto->Mean[CharNormY], Delta,
Proto->Weight.Elliptical[CharNormY], Match);
}
Delta = feature.Params[CharNormRx] - Proto->Mean[CharNormRx];
Match += Delta * Delta * Proto->Weight.Elliptical[CharNormRx];
if (DebugMatch) {
tprintf("Height: Proto=%g, Delta=%g, Var=%g, Dist=%g\n",
Proto->Mean[CharNormRx], Delta,
Proto->Weight.Elliptical[CharNormRx], Match);
}
// Ry is width! See intfx.cpp.
Delta = feature.Params[CharNormRy] - Proto->Mean[CharNormRy];
if (DebugMatch) {
tprintf("Width: Proto=%g, Delta=%g, Var=%g\n",
Proto->Mean[CharNormRy], Delta,
Proto->Weight.Elliptical[CharNormRy]);
}
Delta = Delta * Delta * Proto->Weight.Elliptical[CharNormRy];
Delta *= kWidthErrorWeighting;
Match += Delta;
if (DebugMatch) {
tprintf("Total Dist=%g, scaled=%g, sigmoid=%g, penalty=%g\n",
Match, Match / classify_norm_adj_midpoint,
NormEvidenceOf(Match), 256 * (1 - NormEvidenceOf(Match)));
}
if (Match < BestMatch)
BestMatch = Match;
ProtoId++;
}
return 1.0 - NormEvidenceOf(BestMatch);
} /* ComputeNormMatch */
void Classify::FreeNormProtos() {
if (NormProtos != NULL) {
for (int i = 0; i < NormProtos->NumProtos; i++)
FreeProtoList(&NormProtos->Protos[i]);
Efree(NormProtos->Protos);
Efree(NormProtos->ParamDesc);
Efree(NormProtos);
NormProtos = NULL;
}
}
} // namespace tesseract
/**----------------------------------------------------------------------------
Private Code
----------------------------------------------------------------------------**/
/**********************************************************************
* NormEvidenceOf
*
* Return the new type of evidence number corresponding to this
* normalization adjustment. The equation that represents the transform is:
* 1 / (1 + (NormAdj / midpoint) ^ curl)
**********************************************************************/
double NormEvidenceOf(register double NormAdj) {
NormAdj /= classify_norm_adj_midpoint;
if (classify_norm_adj_curl == 3)
NormAdj = NormAdj * NormAdj * NormAdj;
else if (classify_norm_adj_curl == 2)
NormAdj = NormAdj * NormAdj;
else
NormAdj = pow (NormAdj, classify_norm_adj_curl);
return (1.0 / (1.0 + NormAdj));
}
/*---------------------------------------------------------------------------*/
void PrintNormMatch(FILE *File,
int NumParams,
PROTOTYPE *Proto,
FEATURE Feature) {
/*
** Parameters:
** File open text file to dump match debug info to
** NumParams # of parameters in proto and feature
** Proto[] array of prototype parameters
** Feature[] array of feature parameters
** Globals: none
** Operation: This routine dumps out detailed normalization match info.
** Return: none
** Exceptions: none
** History: Wed Jan 2 09:49:35 1991, DSJ, Created.
*/
int i;
FLOAT32 ParamMatch;
FLOAT32 TotalMatch;
for (i = 0, TotalMatch = 0.0; i < NumParams; i++) {
ParamMatch = (Feature->Params[i] - Mean(Proto, i)) /
StandardDeviation(Proto, i);
fprintf (File, " %6.1f", ParamMatch);
if (i == CharNormY || i == CharNormRx)
TotalMatch += ParamMatch * ParamMatch;
}
fprintf (File, " --> %6.1f (%4.2f)\n",
TotalMatch, NormEvidenceOf (TotalMatch));
} /* PrintNormMatch */
/*---------------------------------------------------------------------------*/
namespace tesseract {
NORM_PROTOS *Classify::ReadNormProtos(FILE *File, inT64 end_offset) {
/*
** Parameters:
** File open text file to read normalization protos from
** Globals: none
** Operation: This routine allocates a new data structure to hold
** a set of character normalization protos. It then fills in
** the data structure by reading from the specified File.
** Return: Character normalization protos.
** Exceptions: none
** History: Wed Dec 19 16:38:49 1990, DSJ, Created.
*/
NORM_PROTOS *NormProtos;
int i;
char unichar[2 * UNICHAR_LEN + 1];
UNICHAR_ID unichar_id;
LIST Protos;
int NumProtos;
/* allocate and initialization data structure */
NormProtos = (NORM_PROTOS *) Emalloc (sizeof (NORM_PROTOS));
NormProtos->NumProtos = unicharset.size();
NormProtos->Protos = (LIST *) Emalloc (NormProtos->NumProtos * sizeof(LIST));
for (i = 0; i < NormProtos->NumProtos; i++)
NormProtos->Protos[i] = NIL_LIST;
/* read file header and save in data structure */
NormProtos->NumParams = ReadSampleSize (File);
NormProtos->ParamDesc = ReadParamDesc (File, NormProtos->NumParams);
/* read protos for each class into a separate list */
while ((end_offset < 0 || ftell(File) < end_offset) &&
fscanf(File, "%s %d", unichar, &NumProtos) == 2) {
if (unicharset.contains_unichar(unichar)) {
unichar_id = unicharset.unichar_to_id(unichar);
Protos = NormProtos->Protos[unichar_id];
for (i = 0; i < NumProtos; i++)
Protos =
push_last (Protos, ReadPrototype (File, NormProtos->NumParams));
NormProtos->Protos[unichar_id] = Protos;
} else {
cprintf("Error: unichar %s in normproto file is not in unichar set.\n",
unichar);
for (i = 0; i < NumProtos; i++)
FreePrototype(ReadPrototype (File, NormProtos->NumParams));
}
SkipNewline(File);
}
return (NormProtos);
} /* ReadNormProtos */
} // namespace tesseract
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