GaborFilter.cpp

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/* Import from Gabor API

Copyright (c) 2002-3 Adriaan Tijsseling


                             All Rights Reserved

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

/*
Description:    Implementation for GaborFilter class
Author:                 Adriaan Tijsseling (AGT)
Copyright:              (c) Copyright 2002 Adriaan Tijsseling. All rights reserved.
Change History (most recent first):
        18/04/2002 - AGT - initial version
*/

#include <cstring>
#include "GaborFilter.h"

#ifndef M_PI
#define M_PI 3.1415926535897932384626433832795
#endif

namespace celeste
{
// default constructor just sets everything to default
GaborFilter::GaborFilter()
{
        mRadius = 16;
        mXYO = 8;
        mSigma = (float)(M_PI);
        mAngle = 0;
        mPhase = 0;
        mFrequency = 1.0;
        mReal = NULL;
        mImaginary = NULL;
}

// destructor: free up memory
GaborFilter::~GaborFilter()
{
        int i;
        
        if ( mReal != NULL )
        {
                for ( i = 0; i < mRadius; i++ ) delete[] mReal[i];
                delete[] mReal;
        }
        if ( mImaginary != NULL )
        {
                for ( i = 0; i < mRadius; i++ ) delete[] mImaginary[i];
                delete[] mImaginary;
        }
}


// set up the filter
void GaborFilter::Initialize( int radius, float a, float f, float s, float p )
{
        float x, y, exponential, sincos;
        
// set internal variables
        mRadius = 2 * radius;
        mXYO = radius;  // origin of filter
        mSigma = s;
        mAngle = a;
        mPhase = p;
        mFrequency = (float)(f * M_PI / 2.0);
        
// allocate memory for this filter
        mReal           = new float*[mRadius];          // real part of filter
        mImaginary      = new float*[mRadius];          // imaginary part of filter

// initialize values of filter
        for ( int i = 0; i < mRadius; i++ )
        {
                mReal[i]          = new float[mRadius];
                mImaginary[i] = new float[mRadius];
                
                for ( int j = 0; j < mRadius; j++ )
                {
                // offset from origin
                        y = (float)( i - mXYO );
                        x = (float)( j - mXYO );
                        
                // calculate exponential part
                        exponential = exp( - ( x*x + y*y ) / mSigma );
                        
                // calculate sin-cos sum
                        sincos = mFrequency * ( y * cos( mAngle ) - x * sin( mAngle ) );
                        mReal[i][j]      = exponential * sin( sincos );
                        mImaginary[i][j] = exponential * ( cos( sincos ) - exp( (float)((-1.0*M_PI*M_PI)/2.0f) ) );
                }
        }
}


// save the filter image
void GaborFilter::Save( char* file, int angle, int freq )
{
        PGMImage        pgmImage;
        char            filename[256];
        char            suffix[32];
        
        strcpy( filename, file );
        sprintf( suffix, "gf_i_%d_%d.pgm", angle, freq );
        strcat( filename, suffix );
        pgmImage.WriteScaled( filename, mImaginary, mRadius, mRadius );
        strcpy( filename, file );
        sprintf( suffix, "gf_r_%d_%d.pgm", angle, freq );
        strcat( filename, suffix );
        pgmImage.WriteScaled( filename, mReal, mRadius, mRadius );
}

}; // namespace