二值图像连通区域标记

#include "cv.h"
#include "highgui.h"
#include
using namespace std;

#define NO_OBJECT 0
//#define MIN(x, y) (((x) < (y)) ? (x) : (y))
#define ELEM(img, r, c) (CV_IMAGE_ELEM(img, unsigned char, r, c))
#define ONETWO(L, r, c, col) (L[(r) * (col) + c])

int find( int set[], int x )
{
int r = x;
while ( set[r] != r )
r = set[r];
return r;
}
/*
labeling scheme
+-+-+-+
|D|C|E|
+-+-+-+
|B|A| |
+-+-+-+
| | | |
+-+-+-+
A is the center pixel of a neighborhood. In the 3 versions of
connectedness:
4: A connects to B and C
6: A connects to B, C, and D
8: A connects to B, C, D, and E
*/
/////////////////////////////
//by yysdsyl
//
//input:img -- gray image
// n -- n connectedness
// labels -- label of each pixel, labels[row * col]
//output: number of connected regions
//
//
//
int bwlabel(string filenane, int n, int* labels)
{
IplImage* img = (IplImage* )cvLoadImage(filenane.data(), 0);

if(n != 4 && n != 8)
n = 4;
int nr = img->height;
int nc = img->width;
int total = nr * nc;
// results
memset(labels, 0, total * sizeof(int));
int nobj = 0; // number of objects found in image
// other variables
int* lset = new int[total]; // label table
memset(lset, 0, total * sizeof(int));
int ntable = 0;
for( int r = 0; r < nr; r++ )
{
for( int c = 0; c < nc; c++ )
{
if ( ELEM(img, r, c) ) // if A is an object
{
// get the neighboring pixels B, C, D, and E
int B, C, D, E;
if ( c == 0 )
B = 0;
else
B = find( lset, ONETWO(labels, r, c - 1, nc) );
if ( r == 0 )
C = 0;
else
C = find( lset, ONETWO(labels, r - 1, c, nc) );
if ( r == 0 || c == 0 )
D = 0;
else
D = find( lset, ONETWO(labels, r - 1, c - 1, nc) );
if ( r == 0 || c == nc - 1 )
E = 0;
else
E = find( lset, ONETWO(labels, r - 1, c + 1, nc) );
if ( n == 4 )
{
// apply 4 connectedness
if ( B && C )
{ // B and C are labeled
if ( B == C )
ONETWO(labels, r, c, nc) = B;
else {
lset[C] = B;

ONETWO(labels, r, c, nc) = B;
}
}
else if ( B ) // B is object but C is not
ONETWO(labels, r, c, nc) = B;
else if ( C ) // C is object but B is not
ONETWO(labels, r, c, nc) = C;
else
{ // B, C, D not object - new object
// label and put into table
ntable++;
ONETWO(labels, r, c, nc) = lset[ ntable ] = ntable;
}
}
else if ( n == 6 )
{
// apply 6 connected ness
if ( D ) // D object, copy label and move on
ONETWO(labels, r, c, nc) = D;
else if ( B && C )
{ // B and C are labeled
if ( B == C )
ONETWO(labels, r, c, nc) = B;
else
{
int tlabel = MIN(B,C);
lset[B] = tlabel;
lset[C] = tlabel;
ONETWO(labels, r, c, nc) = tlabel;
}
}
else if ( B ) // B is object but C is not
ONETWO(labels, r, c, nc) = B;
else if ( C ) // C is object but B is not
ONETWO(labels, r, c, nc) = C;
else
{ // B, C, D not object - new object
// label and put into table
ntable++;
ONETWO(labels, r, c, nc) = lset[ ntable ] = ntable;
}
}
else if ( n == 8 )
{
// apply 8 connectedness
if ( B || C || D || E )
{
int tlabel = B;
if ( B )
tlabel = B;
else if ( C )
tlabel = C;
else if ( D )
tlabel = D;
else if ( E )
tlabel = E;
ONETWO(labels, r, c, nc) = tlabel;
if ( B && B != tlabel )
lset[B] = tlabel;
if ( C && C != tlabel )
lset[C] = tlabel;
i

f ( D && D != tlabel )
lset[D] = tlabel;
if ( E && E != tlabel )
lset[E] = tlabel;
}
else
{
// label and put into table
ntable++;
ONETWO(labels, r, c, nc) = lset[ ntable ] = ntable;
}
}
}
else
{
ONETWO(labels, r, c, nc) = NO_OBJECT; // A is not an object so leave it
}
}
}
// consolidate component table
for( int i = 0; i <= ntable; i++ )
lset[i] = find( lset, i );
// run image through the look-up table
for( r = 0; r < nr; r++ )
for( int c = 0; c < nc; c++ )
ONETWO(labels, r, c, nc) = lset[ ONETWO(labels, r, c, nc) ];
// count up the objects in the image
for( i = 0; i <= ntable; i++ )
lset[i] = 0;
for( r = 0; r < nr; r++ )
for( int c = 0; c < nc; c++ )
lset[ ONETWO(labels, r, c, nc) ]++;
// number the objects from 1 through n objects
nobj = 0;
lset[0] = 0;
for( i = 1; i <= ntable; i++ )
if ( lset[i] > 0 )
lset[i] = ++nobj;
// run through the look-up table again
for( r = 0; r < nr; r++ )
for( int c = 0; c < nc; c++ )
ONETWO(labels, r, c, nc) = lset[ ONETWO(labels, r, c, nc) ];
//
delete[] lset;
return nobj;
}