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https://github.com/tesseract-ocr/tesseract.git
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694d3f2c20
git-svn-id: https://tesseract-ocr.googlecode.com/svn/trunk@291 d0cd1f9f-072b-0410-8dd7-cf729c803f20
368 lines
14 KiB
C++
368 lines
14 KiB
C++
/******************************************************************************
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** Filename: mfx.c
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** Purpose: Micro feature extraction routines
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** Author: Dan Johnson
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** History: 7/21/89, DSJ, Created.
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**
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** (c) Copyright Hewlett-Packard Company, 1988.
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** Licensed under the Apache License, Version 2.0 (the "License");
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** you may not use this file except in compliance with the License.
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** You may obtain a copy of the License at
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** http://www.apache.org/licenses/LICENSE-2.0
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** Unless required by applicable law or agreed to in writing, software
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** distributed under the License is distributed on an "AS IS" BASIS,
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** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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** See the License for the specific language governing permissions and
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** limitations under the License.
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******************************************************************************/
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/**----------------------------------------------------------------------------
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Include Files and Type Defines
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----------------------------------------------------------------------------**/
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#include "mfdefs.h"
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#include "mfoutline.h"
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#include "clusttool.h" //NEEDED
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#include "const.h"
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#include "intfx.h"
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#include "varable.h"
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#include <math.h>
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/**----------------------------------------------------------------------------
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Variables
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----------------------------------------------------------------------------**/
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/* old numbers corresponded to 10.0 degrees and 80.0 degrees */
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double_VAR(classify_min_slope, 0.414213562,
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"Slope below which lines are called horizontal");
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double_VAR(classify_max_slope, 2.414213562,
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"Slope above which lines are called vertical");
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double_VAR(classify_noise_segment_length, 0.00,
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"Length below which outline segments are treated as noise");
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/**----------------------------------------------------------------------------
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Macros
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----------------------------------------------------------------------------**/
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/* miscellaneous macros */
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#define NormalizeAngle(A) ( (((A)<0)?((A)+2*PI):(A)) / (2*PI) )
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/*----------------------------------------------------------------------------
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Private Function Prototypes
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-----------------------------------------------------------------------------*/
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void ComputeBulges(MFOUTLINE Start, MFOUTLINE End, MICROFEATURE MicroFeature);
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FLOAT32 ComputeOrientation(MFEDGEPT *Start, MFEDGEPT *End);
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MICROFEATURES ConvertToMicroFeatures(MFOUTLINE Outline,
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MICROFEATURES MicroFeatures);
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MICROFEATURE ExtractMicroFeature(MFOUTLINE Start, MFOUTLINE End);
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void SmearBulges(MICROFEATURES MicroFeatures, FLOAT32 XScale, FLOAT32 YScale);
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/**----------------------------------------------------------------------------
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Public Code
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----------------------------------------------------------------------------**/
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/*---------------------------------------------------------------------------*/
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CHAR_FEATURES BlobMicroFeatures(TBLOB *Blob, LINE_STATS *LineStats) {
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/*
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** Parameters:
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** Blob blob to extract micro-features from
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** LineStats statistics for text line normalization
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** Operation:
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** This routine extracts micro-features from the specified
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** blob and returns a list of the micro-features. All
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** micro-features are normalized according to the specified
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** line statistics.
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** Return: List of micro-features extracted from the blob.
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** Exceptions: none
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** History: 7/21/89, DSJ, Created.
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*/
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MICROFEATURES MicroFeatures = NIL;
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FLOAT32 XScale, YScale;
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LIST Outlines;
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LIST RemainingOutlines;
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MFOUTLINE Outline;
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INT_FEATURE_ARRAY blfeatures;
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INT_FEATURE_ARRAY cnfeatures;
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INT_FX_RESULT_STRUCT results;
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if (Blob != NULL) {
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Outlines = ConvertBlob (Blob);
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// NormalizeOutlines(Outlines, LineStats, &XScale, &YScale);
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if (!ExtractIntFeat(Blob, blfeatures, cnfeatures, &results))
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return NULL;
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XScale = 0.2f / results.Ry;
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YScale = 0.2f / results.Rx;
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RemainingOutlines = Outlines;
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iterate(RemainingOutlines) {
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Outline = (MFOUTLINE) first_node (RemainingOutlines);
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CharNormalizeOutline (Outline,
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results.Xmean, results.Ymean,
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XScale, YScale);
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}
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RemainingOutlines = Outlines;
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iterate(RemainingOutlines) {
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Outline = (MFOUTLINE) first_node (RemainingOutlines);
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FindDirectionChanges(Outline, classify_min_slope, classify_max_slope);
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FilterEdgeNoise(Outline, classify_noise_segment_length);
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MarkDirectionChanges(Outline);
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SmearExtremities(Outline, XScale, YScale);
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MicroFeatures = ConvertToMicroFeatures (Outline, MicroFeatures);
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}
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SmearBulges(MicroFeatures, XScale, YScale);
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FreeOutlines(Outlines);
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}
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return ((CHAR_FEATURES) MicroFeatures);
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} /* BlobMicroFeatures */
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/**----------------------------------------------------------------------------
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Private Macros
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----------------------------------------------------------------------------**/
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/**********************************************************************
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* angle_of
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*
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* Return the angle of the line between two points.
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**********************************************************************/
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#define angle_of(x1,y1,x2,y2) \
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((x2-x1) ? \
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(atan2 (y2-y1, x2-x1)) : \
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((y2<y1) ? (- PI / 2.0) : (PI / 2.0))) \
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/**********************************************************************
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* scale_angle
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*
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* Make sure that the angle is non-negative. Scale it to the right
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* amount.
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**********************************************************************/
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#define scale_angle(x) \
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(((x<0) ? (2.0 * PI + x) : (x)) * 0.5 / PI) \
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/*---------------------------------------------------------------------------
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Private Code
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---------------------------------------------------------------------------*/
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/*---------------------------------------------------------------------------*/
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void ComputeBulges(MFOUTLINE Start, MFOUTLINE End, MICROFEATURE MicroFeature) {
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/*
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** Parameters:
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** Start starting point of micro-feature
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** End ending point of micro-feature
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** MicroFeature micro-feature whose bulges are to be computed
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** Globals: none
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** Operation:
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** This routine computes the size of the "bulges" of the
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** specified micro-feature. The bulges are the deviations
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** of the micro-features from a straight line at the 1/3
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** and 2/3 points along the straight line approximation of
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** the micro-feature. The size of each bulge is normalized
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** to the range -0.5 to 0.5. A positive bulge indicates a
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** deviation in the counterclockwise direction and vice versa.
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** A size of 0.5 (+ or -) corresponds to the largest bulge that
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** could ever occur for the given feature independent of
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** orientation. This routine assumes that Start
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** and End are not the same point. It also assumes that the
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** orientation and length parameters of the micro-feature
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** have already been computed.
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** Return: none
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** Exceptions: none
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** History: 7/27/89, DSJ, Created.
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*/
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MATRIX_2D Matrix;
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MFEDGEPT *Origin;
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MFOUTLINE SegmentStart, SegmentEnd;
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FPOINT CurrentPoint, LastPoint;
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FLOAT32 BulgePosition;
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/* check for simple case */
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if (End == NextPointAfter (Start))
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MicroFeature[FIRSTBULGE] = MicroFeature[SECONDBULGE] = 0;
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else {
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Origin = PointAt (Start);
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InitMatrix(&Matrix);
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RotateMatrix (&Matrix, MicroFeature[ORIENTATION] * -2.0 * PI);
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TranslateMatrix (&Matrix, -Origin->Point.x, -Origin->Point.y);
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SegmentEnd = Start;
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CurrentPoint.x = 0.0f;
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CurrentPoint.y = 0.0f;
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BulgePosition = MicroFeature[MFLENGTH] / 3;
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LastPoint = CurrentPoint;
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while (CurrentPoint.x < BulgePosition) {
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SegmentStart = SegmentEnd;
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SegmentEnd = NextPointAfter (SegmentStart);
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LastPoint = CurrentPoint;
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MapPoint(&Matrix, PointAt(SegmentEnd)->Point, &CurrentPoint);
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}
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MicroFeature[FIRSTBULGE] =
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XIntersectionOf(LastPoint, CurrentPoint, BulgePosition);
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BulgePosition *= 2;
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// Prevents from copying the points before computing the bulge if
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// CurrentPoint will not change. (Which would cause to output nan
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// for the SecondBulge.)
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if (CurrentPoint.x < BulgePosition)
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LastPoint = CurrentPoint;
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while (CurrentPoint.x < BulgePosition) {
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SegmentStart = SegmentEnd;
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SegmentEnd = NextPointAfter (SegmentStart);
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LastPoint = CurrentPoint;
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MapPoint(&Matrix, PointAt(SegmentEnd)->Point, &CurrentPoint);
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}
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MicroFeature[SECONDBULGE] =
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XIntersectionOf(LastPoint, CurrentPoint, BulgePosition);
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MicroFeature[FIRSTBULGE] /= BULGENORMALIZER * MicroFeature[MFLENGTH];
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MicroFeature[SECONDBULGE] /= BULGENORMALIZER * MicroFeature[MFLENGTH];
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}
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} /* ComputeBulges */
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/*---------------------------------------------------------------------------*/
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FLOAT32 ComputeOrientation(MFEDGEPT *Start, MFEDGEPT *End) {
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/*
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** Parameters:
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** Start starting edge point of micro-feature
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** End ending edge point of micro-feature
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** Globals: none
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** Operation:
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** This routine computes the orientation parameter of the
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** specified micro-feature. The orientation is the angle of
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** the vector from Start to End. It is normalized to a number
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** between 0 and 1 where 0 corresponds to 0 degrees and 1
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** corresponds to 360 degrees. The actual range is [0,1), i.e.
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** 1 is excluded from the range (since it is actual the
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** same orientation as 0). This routine assumes that Start
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** and End are not the same point.
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** Return: Orientation parameter for the specified micro-feature.
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** Exceptions: none
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** History: 7/27/89, DSJ, Created.
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*/
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FLOAT32 Orientation;
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Orientation = NormalizeAngle (AngleFrom (Start->Point, End->Point));
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/* ensure that round-off errors do not put circular param out of range */
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if ((Orientation < 0) || (Orientation >= 1))
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Orientation = 0;
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return (Orientation);
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} /* ComputeOrientation */
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/*---------------------------------------------------------------------------*/
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MICROFEATURES ConvertToMicroFeatures(MFOUTLINE Outline,
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MICROFEATURES MicroFeatures) {
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/*
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** Parameters:
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** Outline outline to extract micro-features from
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** MicroFeatures list of micro-features to add to
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** Globals: none
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** Operation:
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** This routine
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** Return: List of micro-features with new features added to front.
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** Exceptions: none
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** History: 7/26/89, DSJ, Created.
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*/
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MFOUTLINE Current;
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MFOUTLINE Last;
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MFOUTLINE First;
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MICROFEATURE NewFeature;
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if (DegenerateOutline (Outline))
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return (MicroFeatures);
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First = NextExtremity (Outline);
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Last = First;
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do {
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Current = NextExtremity (Last);
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NewFeature = ExtractMicroFeature (Last, Current);
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if (NewFeature != NULL)
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MicroFeatures = push (MicroFeatures, NewFeature);
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Last = Current;
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}
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while (Last != First);
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return (MicroFeatures);
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} /* ConvertToMicroFeatures */
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/*---------------------------------------------------------------------------*/
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MICROFEATURE ExtractMicroFeature(MFOUTLINE Start, MFOUTLINE End) {
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/*
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** Parameters:
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** Start starting point of micro-feature
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** End ending point of micro-feature
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** Globals: none
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** Operation:
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** This routine computes the feature parameters which describe
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** the micro-feature that starts and Start and ends at End.
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** A new micro-feature is allocated, filled with the feature
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** parameters, and returned. The routine assumes that
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** Start and End are not the same point. If they are the
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** same point, NULL is returned, a warning message is
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** printed, and the current outline is dumped to stdout.
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** Return: New micro-feature or NULL if the feature was rejected.
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** Exceptions: none
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** History: 7/26/89, DSJ, Created.
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** 11/17/89, DSJ, Added handling for Start and End same point.
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*/
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MICROFEATURE NewFeature;
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MFEDGEPT *P1, *P2;
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P1 = PointAt (Start);
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P2 = PointAt (End);
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NewFeature = NewMicroFeature ();
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NewFeature[XPOSITION] = AverageOf (P1->Point.x, P2->Point.x);
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NewFeature[YPOSITION] = AverageOf (P1->Point.y, P2->Point.y);
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NewFeature[MFLENGTH] = DistanceBetween (P1->Point, P2->Point);
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NewFeature[ORIENTATION] = NormalizedAngleFrom(&P1->Point, &P2->Point, 1.0);
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ComputeBulges(Start, End, NewFeature);
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return (NewFeature);
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} /* ExtractMicroFeature */
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/*---------------------------------------------------------------------------*/
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void SmearBulges(MICROFEATURES MicroFeatures, FLOAT32 XScale, FLOAT32 YScale) {
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/*
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** Parameters:
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** MicroFeatures features to be smeared
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** XScale # of normalized units per pixel in x dir
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** YScale # of normalized units per pixel in y dir
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** Globals: none
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** Operation: Add a random amount to each bulge parameter of each
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** feature. The amount added is between -0.5 pixels and
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** 0.5 pixels. This is done to prevent the prototypes
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** generated in training from being unrealistically tight.
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** Return: none
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** Exceptions: none
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** History: Thu Jun 28 18:03:38 1990, DSJ, Created.
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*/
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MICROFEATURE MicroFeature;
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FLOAT32 MinSmear;
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FLOAT32 MaxSmear;
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FLOAT32 Cos, Sin;
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FLOAT32 Scale;
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iterate(MicroFeatures) {
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MicroFeature = NextFeatureOf (MicroFeatures);
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Cos = fabs(cos(2.0 * PI * MicroFeature[ORIENTATION]));
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Sin = fabs(sin(2.0 * PI * MicroFeature[ORIENTATION]));
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Scale = YScale * Cos + XScale * Sin;
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MinSmear = -0.5 * Scale / (BULGENORMALIZER * MicroFeature[MFLENGTH]);
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MaxSmear = 0.5 * Scale / (BULGENORMALIZER * MicroFeature[MFLENGTH]);
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MicroFeature[FIRSTBULGE] += UniformRandomNumber (MinSmear, MaxSmear);
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MicroFeature[SECONDBULGE] += UniformRandomNumber (MinSmear, MaxSmear);
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}
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} /* SmearBulges */
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