// API
int adsf_union(int *t, int n, int a, int b)
{
assert(a >= 0 && a < n);
assert(b >= 0 && b < n);
a = adsf_find(t, n, a);
b = adsf_find(t, n, b);
int c = a;
if (a != b)
c = adsf_make_link(t, a, b);
return c;
}
// connected components of positive pixels of the image rep
static void connected_component_filter(int *rep, int w, int h, float *in, float intensity_threshold)
{
adsf_begin(rep, w*h);
// remove from dsf pixels with NANs in input
for (int i = 0; i < w*h; i++)
if (isnan(in[i]))
rep[i] = -1;
for (int j = 0; j < h - 1; j++)
for (int i = 0; i < w - 1; i++)
{
int p0 = j*w + i;
int p1 = j*w + i+1;
int p2 = (j+1)*w + i;
if (rep[p0] >= 0 && rep[p1] >= 0 &&
fabs(in[p0] - in[p1]) < intensity_threshold)
adsf_union(rep, w*h, p0, p1);
if (rep[p0] >= 0 && rep[p2] >= 0 &&
fabs(in[p0] - in[p2]) < intensity_threshold)
adsf_union(rep, w*h, p0, p2);
}
for (int i = 0; i < w*h; i++)
if (rep[i] >= 0)
rep[i] = adsf_find(rep, w*h, i);
}
// API
int adsf_find(int *t, int n, int a) {
assert(a >= 0 && a < n);
if (a != t[a])
t[a] = adsf_find(t, n, t[a]);
return t[a];
}