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/* SPDX-License-Identifier: GPL-2.0-or-later */
/** \file
* \ingroup freestyle
* \brief Class to perform gaussian filtering operations on an image
*/
#include <cstdlib>
#include "GaussianFilter.h"
namespace Freestyle {
GaussianFilter::GaussianFilter(float iSigma)
{
_sigma = iSigma;
_mask = nullptr;
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()
{
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()
{
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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