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/*
Copyright (C) 2006 Pedro Felzenszwalb
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/* simple filters */
#ifndef FILTER_H
#define FILTER_H
#include <algorithm>
#include <cmath>
#include <vector>
#include "third_party/segment/image.h"
#include "third_party/segment/misc.h"
#include "third_party/segment/convolve.h"
#include "third_party/segment/imconv.h"
#define WIDTH 4.0
/* normalize mask so it integrates to one */
static void normalize(std::vector<float> *mask) {
int len = mask->size();
float sum = 0;
for (int i = 1; i < len; i++) {
sum += (float)fabs((*mask)[i]);
}
sum = 2 * sum + (float)fabs((*mask)[0]);
for (int i = 0; i < len; i++) {
(*mask)[i] /= sum;
}
}
/* make filters */
#define MAKE_FILTER(name, fun) \
static std::vector<float> make_##name(float sigma) { \
sigma = std::max(sigma, 0.01F); \
int len = (int)ceil(sigma * WIDTH) + 1; \
std::vector<float> mask(len); \
for (int i = 0; i < len; i++) { \
mask[i] = fun; \
} \
return mask; \
}
MAKE_FILTER(fgauss, (float)exp(-0.5 * square(i / sigma)));
/* convolve image with gaussian filter */
static image<float> *smooth(image<float> *src, float sigma) {
std::vector<float> mask = make_fgauss(sigma);
normalize(&mask);
image<float> *tmp = new image<float>(src->height(), src->width(), false);
image<float> *dst = new image<float>(src->width(), src->height(), false);
convolve_even(src, tmp, mask);
convolve_even(tmp, dst, mask);
delete tmp;
return dst;
}
/* convolve image with gaussian filter */
image<float> *smooth(image<uchar> *src, float sigma) {
image<float> *tmp = imageUCHARtoFLOAT(src);
image<float> *dst = smooth(tmp, sigma);
delete tmp;
return dst;
}
#endif