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/*
* 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, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
/** \file
* \ingroup freestyle
* \brief Class to perform gaussian filtering operations on an image
*/
#include <stdlib.h>
#include "GaussianFilter.h"
namespace Freestyle {
GaussianFilter::GaussianFilter(float iSigma)
{
_sigma = iSigma;
_mask = 0;
computeMask();
}
GaussianFilter::GaussianFilter(const GaussianFilter &iBrother)
{
_sigma = iBrother._sigma;
_maskSize = iBrother._maskSize;
_bound = iBrother._bound;
_storedMaskSize = iBrother._storedMaskSize;
_mask = new float[_maskSize * _maskSize];
memcpy(_mask, iBrother._mask, _maskSize * _maskSize * sizeof(float));
}
GaussianFilter &GaussianFilter::operator=(const GaussianFilter &iBrother)
{
_sigma = iBrother._sigma;
_maskSize = iBrother._maskSize;
_bound = iBrother._bound;
_storedMaskSize = iBrother._storedMaskSize;
_mask = new float[_storedMaskSize * _storedMaskSize];
memcpy(_mask, iBrother._mask, _storedMaskSize * _storedMaskSize * sizeof(float));
return *this;
}
GaussianFilter::~GaussianFilter()
{
if (0 != _mask) {
delete[] _mask;
}
}
int GaussianFilter::computeMaskSize(float sigma)
{
int maskSize = (int)floor(4 * sigma) + 1;
if (0 == (maskSize % 2)) {
++maskSize;
}
return maskSize;
}
void GaussianFilter::setSigma(float sigma)
{
_sigma = sigma;
computeMask();
}
void GaussianFilter::computeMask()
{
if (0 != _mask) {
delete[] _mask;
}
_maskSize = computeMaskSize(_sigma);
_storedMaskSize = (_maskSize + 1) >> 1;
_bound = _storedMaskSize - 1;
float norm = _sigma * _sigma * 2.0f * M_PI;
float invNorm = 1.0f / norm;
_mask = new float[_storedMaskSize * _storedMaskSize * sizeof(float)];
for (int i = 0; i < _storedMaskSize; ++i) {
for (int j = 0; j < _storedMaskSize; ++j) {
#if 0
_mask[i * _storedMaskSize + j] = exp(-(i * i + j * j) / (2.0 * _sigma * _sigma));
#else
_mask[i * _storedMaskSize + j] = invNorm * exp(-(i * i + j * j) / (2.0 * _sigma * _sigma));
#endif
}
}
}
} /* namespace Freestyle */
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