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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
*/
#ifndef SEGMENT_IMAGE
#define SEGMENT_IMAGE
#include <cstdlib>
#include <image.h>
#include <misc.h>
#include <filter.h>
#include "segment-graph.h"
// random color
rgb random_rgb(){
rgb c;
double r;
c.r = (uchar)random();
c.g = (uchar)random();
c.b = (uchar)random();
return c;
}
// dissimilarity measure between pixels
static inline float diff(image<float> *r, image<float> *g, image<float> *b,
int x1, int y1, int x2, int y2) {
return sqrt(square(imRef(r, x1, y1)-imRef(r, x2, y2)) +
square(imRef(g, x1, y1)-imRef(g, x2, y2)) +
square(imRef(b, x1, y1)-imRef(b, x2, y2)));
}
/*
* Segment an image
*
* Returns a color image representing the segmentation.
*
* im: image to segment.
* sigma: to smooth the image.
* c: constant for treshold function.
* min_size: minimum component size (enforced by post-processing stage).
* num_ccs: number of connected components in the segmentation.
*/
image<rgb> *segment_image(image<rgb> *im, float sigma, float c, int min_size,
int *num_ccs) {
int width = im->width();
int height = im->height();
image<float> *r = new image<float>(width, height);
image<float> *g = new image<float>(width, height);
image<float> *b = new image<float>(width, height);
// smooth each color channel
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
imRef(r, x, y) = imRef(im, x, y).r;
imRef(g, x, y) = imRef(im, x, y).g;
imRef(b, x, y) = imRef(im, x, y).b;
}
}
image<float> *smooth_r = smooth(r, sigma);
image<float> *smooth_g = smooth(g, sigma);
image<float> *smooth_b = smooth(b, sigma);
delete r;
delete g;
delete b;
// build graph
edge *edges = new edge[width*height*4];
int num = 0;
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
if (x < width-1) {
edges[num].a = y * width + x;
edges[num].b = y * width + (x+1);
edges[num].w = diff(smooth_r, smooth_g, smooth_b, x, y, x+1, y);
num++;
}
if (y < height-1) {
edges[num].a = y * width + x;
edges[num].b = (y+1) * width + x;
edges[num].w = diff(smooth_r, smooth_g, smooth_b, x, y, x, y+1);
num++;
}
if ((x < width-1) && (y < height-1)) {
edges[num].a = y * width + x;
edges[num].b = (y+1) * width + (x+1);
edges[num].w = diff(smooth_r, smooth_g, smooth_b, x, y, x+1, y+1);
num++;
}
if ((x < width-1) && (y > 0)) {
edges[num].a = y * width + x;
edges[num].b = (y-1) * width + (x+1);
edges[num].w = diff(smooth_r, smooth_g, smooth_b, x, y, x+1, y-1);
num++;
}
}
}
delete smooth_r;
delete smooth_g;
delete smooth_b;
// segment
universe *u = segment_graph(width*height, num, edges, c);
// post process small components
for (int i = 0; i < num; i++) {
int a = u->find(edges[i].a);
int b = u->find(edges[i].b);
if ((a != b) && ((u->size(a) < min_size) || (u->size(b) < min_size)))
u->join(a, b);
}
delete [] edges;
*num_ccs = u->num_sets();
image<rgb> *output = new image<rgb>(width, height);
// pick random colors for each component
rgb *colors = new rgb[width*height];
for (int i = 0; i < width*height; i++)
colors[i] = random_rgb();
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
int comp = u->find(y * width + x);
imRef(output, x, y) = colors[comp];
}
}
delete [] colors;
delete u;
return output;
}
#endif
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