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/******************************************************************************
** Filename: features.h
** Purpose: Generic definition of a feature.
** 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.
******************************************************************************/
#ifndef FEATURES_H
#define FEATURES_H
#include "blobs.h"
#include <cstdio>
namespace tesseract {
class DENORM;
#undef Min
#undef Max
#define FEAT_NAME_SIZE 80
// A character is described by multiple sets of extracted features. Each
// set contains a number of features of a particular type, for example, a
// set of bays, or a set of closures, or a set of microfeatures. Each
// feature consists of a number of parameters. All features within a
// feature set contain the same number of parameters. All circular
// parameters are required to be the first parameters in the feature.
struct PARAM_DESC {
bool Circular; // true if dimension wraps around
bool NonEssential; // true if dimension not used in searches
float Min; // low end of range for circular dimensions
float Max; // high end of range for circular dimensions
float Range; // Max - Min
float HalfRange; // (Max - Min)/2
float MidRange; // (Max + Min)/2
};
struct FEATURE_DESC_STRUCT {
uint16_t NumParams; // total # of params
const char* ShortName; // short name for feature
const PARAM_DESC* ParamDesc; // array - one per param
};
using FEATURE_DESC = FEATURE_DESC_STRUCT*;
struct FEATURE_STRUCT {
const FEATURE_DESC_STRUCT* Type; // points to description of feature type
float Params[1]; // variable size array - params for feature
};
using FEATURE = FEATURE_STRUCT*;
struct FEATURE_SET_STRUCT {
uint16_t NumFeatures; // number of features in set
uint16_t MaxNumFeatures; // maximum size of feature set
FEATURE Features[1]; // variable size array of features
};
using FEATURE_SET = FEATURE_SET_STRUCT*;
// A generic character description as a char pointer. In reality, it will be
// a pointer to some data structure. Paired feature extractors/matchers need
// to agree on the data structure to be used, however, the high level
// classifier does not need to know the details of this data structure.
using CHAR_FEATURES = char*;
/*----------------------------------------------------------------------
Macros for defining the parameters of a new features
----------------------------------------------------------------------*/
#define StartParamDesc(Name) const PARAM_DESC Name[] = {
#define DefineParam(Circular, NonEssential, Min, Max) \
{Circular, \
NonEssential, \
Min, \
Max, \
(Max) - (Min), \
(((Max) - (Min)) / 2.0), \
(((Max) + (Min)) / 2.0)},
#define EndParamDesc };
/*----------------------------------------------------------------------
Macro for describing a new feature. The parameters of the macro
are as follows:
DefineFeature (Name, NumLinear, NumCircular, ShortName, ParamName)
----------------------------------------------------------------------*/
#define DefineFeature(Name, NL, NC, SN, PN) \
const FEATURE_DESC_STRUCT Name = {((NL) + (NC)), SN, PN};
/*----------------------------------------------------------------------
Generic routines that work for all feature types
----------------------------------------------------------------------*/
bool AddFeature(FEATURE_SET FeatureSet, FEATURE Feature);
TESS_API
void FreeFeature(FEATURE Feature);
TESS_API
void FreeFeatureSet(FEATURE_SET FeatureSet);
TESS_API
FEATURE NewFeature(const FEATURE_DESC_STRUCT* FeatureDesc);
FEATURE_SET NewFeatureSet(int NumFeatures);
FEATURE_SET ReadFeatureSet(FILE* File, const FEATURE_DESC_STRUCT* FeatureDesc);
void WriteFeatureSet(FEATURE_SET FeatureSet, STRING* str);
} // namespace tesseract
#endif
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