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tesseract/classify/mfx.cpp

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/******************************************************************************
** Filename: mfx.c
** Purpose: Micro feature extraction routines
** Author: Dan Johnson
** History: 7/21/89, 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 "mfdefs.h"
#include "mfoutline.h"
#include "clusttool.h" //NEEDED
#include "const.h"
#include "intfx.h"
#include "normalis.h"
#include "params.h"
#include <math.h>
/**----------------------------------------------------------------------------
Variables
----------------------------------------------------------------------------**/
/* old numbers corresponded to 10.0 degrees and 80.0 degrees */
double_VAR(classify_min_slope, 0.414213562,
"Slope below which lines are called horizontal");
double_VAR(classify_max_slope, 2.414213562,
"Slope above which lines are called vertical");
/**----------------------------------------------------------------------------
Macros
----------------------------------------------------------------------------**/
/* miscellaneous macros */
#define NormalizeAngle(A) ( (((A)<0)?((A)+2*PI):(A)) / (2*PI) )
/*----------------------------------------------------------------------------
Private Function Prototypes
-----------------------------------------------------------------------------*/
FLOAT32 ComputeOrientation(MFEDGEPT *Start, MFEDGEPT *End);
MICROFEATURES ConvertToMicroFeatures(MFOUTLINE Outline,
MICROFEATURES MicroFeatures);
MICROFEATURE ExtractMicroFeature(MFOUTLINE Start, MFOUTLINE End);
/**----------------------------------------------------------------------------
Public Code
----------------------------------------------------------------------------**/
/*---------------------------------------------------------------------------*/
CHAR_FEATURES BlobMicroFeatures(TBLOB *Blob, const DENORM& bl_denorm,
const DENORM& cn_denorm,
const INT_FX_RESULT_STRUCT& fx_info) {
/*
** Parameters:
** Blob blob to extract micro-features from
** denorm control parameter to feature extractor
** Operation:
** This routine extracts micro-features from the specified
** blob and returns a list of the micro-features. All
** micro-features are normalized according to the specified
** line statistics.
** Return: List of micro-features extracted from the blob.
** Exceptions: none
** History: 7/21/89, DSJ, Created.
*/
MICROFEATURES MicroFeatures = NIL_LIST;
LIST Outlines;
LIST RemainingOutlines;
MFOUTLINE Outline;
if (Blob != NULL) {
Outlines = ConvertBlob(Blob);
RemainingOutlines = Outlines;
iterate(RemainingOutlines) {
Outline = (MFOUTLINE) first_node (RemainingOutlines);
CharNormalizeOutline(Outline, cn_denorm);
}
RemainingOutlines = Outlines;
iterate(RemainingOutlines) {
Outline = (MFOUTLINE) first_node(RemainingOutlines);
FindDirectionChanges(Outline, classify_min_slope, classify_max_slope);
MarkDirectionChanges(Outline);
MicroFeatures = ConvertToMicroFeatures(Outline, MicroFeatures);
}
FreeOutlines(Outlines);
}
return ((CHAR_FEATURES) MicroFeatures);
} /* BlobMicroFeatures */
/*---------------------------------------------------------------------------
Private Code
---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------*/
FLOAT32 ComputeOrientation(MFEDGEPT *Start, MFEDGEPT *End) {
/*
** Parameters:
** Start starting edge point of micro-feature
** End ending edge point of micro-feature
** Globals: none
** Operation:
** This routine computes the orientation parameter of the
** specified micro-feature. The orientation is the angle of
** the vector from Start to End. It is normalized to a number
** between 0 and 1 where 0 corresponds to 0 degrees and 1
** corresponds to 360 degrees. The actual range is [0,1), i.e.
** 1 is excluded from the range (since it is actual the
** same orientation as 0). This routine assumes that Start
** and End are not the same point.
** Return: Orientation parameter for the specified micro-feature.
** Exceptions: none
** History: 7/27/89, DSJ, Created.
*/
FLOAT32 Orientation;
Orientation = NormalizeAngle (AngleFrom (Start->Point, End->Point));
/* ensure that round-off errors do not put circular param out of range */
if ((Orientation < 0) || (Orientation >= 1))
Orientation = 0;
return (Orientation);
} /* ComputeOrientation */
/*---------------------------------------------------------------------------*/
MICROFEATURES ConvertToMicroFeatures(MFOUTLINE Outline,
MICROFEATURES MicroFeatures) {
/*
** Parameters:
** Outline outline to extract micro-features from
** MicroFeatures list of micro-features to add to
** Globals: none
** Operation:
** This routine
** Return: List of micro-features with new features added to front.
** Exceptions: none
** History: 7/26/89, DSJ, Created.
*/
MFOUTLINE Current;
MFOUTLINE Last;
MFOUTLINE First;
MICROFEATURE NewFeature;
if (DegenerateOutline (Outline))
return (MicroFeatures);
First = NextExtremity (Outline);
Last = First;
do {
Current = NextExtremity (Last);
if (!PointAt(Current)->Hidden) {
NewFeature = ExtractMicroFeature (Last, Current);
if (NewFeature != NULL)
MicroFeatures = push (MicroFeatures, NewFeature);
}
Last = Current;
}
while (Last != First);
return (MicroFeatures);
} /* ConvertToMicroFeatures */
/*---------------------------------------------------------------------------*/
MICROFEATURE ExtractMicroFeature(MFOUTLINE Start, MFOUTLINE End) {
/*
** Parameters:
** Start starting point of micro-feature
** End ending point of micro-feature
** Globals: none
** Operation:
** This routine computes the feature parameters which describe
** the micro-feature that starts and Start and ends at End.
** A new micro-feature is allocated, filled with the feature
** parameters, and returned. The routine assumes that
** Start and End are not the same point. If they are the
** same point, NULL is returned, a warning message is
** printed, and the current outline is dumped to stdout.
** Return: New micro-feature or NULL if the feature was rejected.
** Exceptions: none
** History: 7/26/89, DSJ, Created.
** 11/17/89, DSJ, Added handling for Start and End same point.
*/
MICROFEATURE NewFeature;
MFEDGEPT *P1, *P2;
P1 = PointAt(Start);
P2 = PointAt(End);
NewFeature = NewMicroFeature ();
NewFeature[XPOSITION] = AverageOf(P1->Point.x, P2->Point.x);
NewFeature[YPOSITION] = AverageOf(P1->Point.y, P2->Point.y);
NewFeature[MFLENGTH] = DistanceBetween(P1->Point, P2->Point);
NewFeature[ORIENTATION] = NormalizedAngleFrom(&P1->Point, &P2->Point, 1.0);
NewFeature[FIRSTBULGE] = 0.0f; // deprecated
NewFeature[SECONDBULGE] = 0.0f; // deprecated
return NewFeature;
} /* ExtractMicroFeature */
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